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EPA'S MAP OF RADON ZONES
PENNSYLVANIA
RADON DIVISION
OFFICE OF RADIATION AND INDOOR AIR
U.S. ENVIRONMENTAL PROTECTION AGENCY
SEPTEMBER, 1993
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ACKNOWLEDGEMENTS
This document was prepared by the U.S. Environmental Protection Agency's (EPA's)
Office of Radiation and Indoor Air (ORIA) in conjunction with the U.S. Geological Survey
(USGS). Sharon W. White was the EPA project manager. Numerous other people in ORIA
were instrumental in the development of the Map of Radon Zones, including Lisa Ratcliff,
Kirk Maconaughey, R. Thomas Peake, Dave Rowson, and Steve Page.
EPA would especially like to acknowledge the outstanding effort of the USGS
radon team — Linda Gundersen, Randy Schumann, Jim Otton, Doug Owen, Russell
Dubiel, Kendell Dickinson, and Sandra Szarzi — in developing the technical base for the
Map of Radon Zones.
•
ORIA would also like to recognize the efforts of all the EPA Regional Offices in
coordinating the reviews with the State programs and the Association of American State
Geologists (AASG) for providing a liaison with the State geological surveys. In addition,
appreciation is expressed to all of the State radon programs and geological surveys for their
technical input and review of the Map of Radon Zones.
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rABLE OF CONTENTS
I. OVERVIEW
II. THE USGS/EPA RADON POTENTIAL
ASSESSMENTS:INTRODUCTION
III. REGION 3 GEOLOGIC RADON POTENTIAL
SUMMARY
V. PRELIMINARY GEOLOGIC RADON POTENTIAL
ASSESSMENT OF PENNSYLVANIA
V. EPA'S MAP OF RADON ZONES - PENNSYLVANIA
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OVERVIEW
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Sections 307 and 309 of the 1988 Indoor Radon Abatement Act (IRAA) direct EPA to
identify areas of the United States that have the potential to produce elevated levels of radon.
EPA, the U.S. Geological Survey (USGS), and the Association of American State Geologists
(AASG) have worked closely over the past several years to produce a series of maps and
documents which address these directives. The EPA Map of Radon Zones is a compilation of
that work and fulfills the requirements of sections 307 and 309 of IRAA. The Map of Radon
Zones identifies, on a county-by-county basis, areas of the U.S. that have the highest potential
for elevated indoor radon levels (greater than 4 pCi/L).
The Map of Radon Zones is designed to assist national, State and local governments
and organizations to target their radon program activities and resources. It is also intended to
help building code officials determine areas that are the highest priority for adopting radon-
resistant building practices. The Map of Radon Zones should not be used to determine if
individual homes in any given area need to be tested for radon. EPA recommends that all
homes be tested for radon, regardless of geographic location or the zone designation of
the county in which they are located.
This document provides background information concerning the development of the
Map of Radon Zones. It explains the purposes of the map, the approach for developing the
map (including the respective roles of EPA and USGS), the data sources used, the conclusions
and confidence levels developed for the prediction of radon potential, and the review process
that was conducted to finalize this effort.
BACKGROUND
Radon (Rn222) is a colorless, odorless, radioactive gas. It comes from the natural
decay of uranium that is found in nearly all soils. It typically moves through the ground to
the air above and into homes and other buildings through cracks and openings in the
foundation. Any home, school or workplace may have a radon problem, regardless of
whether it is new or old, well-sealed or drafty, or with or without a basement. Nearly one out
of every 15 homes in the U.S. is estimated to have elevated annual average levels of indoor
radon.
Radon first gained national attention in early 1984, when extremely high levels of
indoor radon were found in areas of Pennsylvania, New Jersey, and New York, along the
Reading Prong-physiographic province. EPA established a Radon Program in 1985 to assist
States and homeowners in reducing their risk of lung cancer from indoor radon.
Since 1985, EPA and USGS have been working together to continually increase our
understanding of radon sources and the migration dynamics that cause elevated indoor radon
levels. Early efforts resulted in the 1987 map entitled "Areas with Potentially High Radon
Levels." This map was based on limited geologic information only because few indoor radon
measurements were available at the time. The development of EPA's Map of Radon Zones
and its technical foundation, USGS1 National Geologic Radon Province Map, has been based
on additional information from six years of the State/EPA Residential Radon Surveys,
independent State residential surveys, and continued expansion of geologic and geophysical
information, particularly the data from the National Uranium Resource Evaluation project.
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of the Map of Radon Zones
EPA's Map of Radon Zones (Figure 1) assigns each of the 3141 counties in the
United States to one of three zones:
o Zone 1 counties have a predicted average indoor screening level > than
4 pCi/L
o Zone 2 counties have a predicted average screening level > 2 pCi/L and
:£ 4 pCi/L
o Zone 3 counties have a predicted average screening level < 2 pCi/L
The Zone designations were determined by assessing five factors that are known to be
important indicators of radon potential: indoor radon measurements, geology, aerial
radioactivity, soil parameters, and foundation types.
The predictions of average screening levels in each of the Zones is an expression of
radon potential in the lowest liveable area of a structure. This map is unable to estimate
actual exposures to radon. EPA recommends methods for testing and fixing individual homes
based on an estimate of actual exposure to radon. For more information on testing and fixing
elevated radon levels in homes consult these EPA publications: A Citizen's Guide to Radon.
the Consumer's Guide to Radon Reduction and the Home Buyer's and Seller's Guide to
Radon.
EPA believes that States, local governments and other organizations can achieve
optimal risk reductions by targeting resources and program activities to high radon potential
areas. Emphasizing targeted approaches (technical assistance, information and outreach
efforts, promotion of real estate mandates and policies and building codes, etc.) in such areas
addresses the greatest potential risks first.
EPA also believes that the use of passive radon control systems in the construction of
new homes in Zone 1 counties, and the activation of those systems if necessitated by follow-
up testing, is a cost effective approach to achieving significant radon risk reduction.
The Map of Radon Zones and its supporting documentation establish no regulatory
requirements. Use of this map by State or local radon programs and building code officials is
voluntary. The information presented on the Map of Radon Zones and in the supporting
documentation is not applicable to radon in water.
n*vi»lnpmant of the Map of Radon Zones
The technical foundation for the Map of Radon Zones is the USGS Geologic Radon
Province Map. In order to examine the radon potential for the United States, the USGS
began by identifying approximately 360 separate geologic provinces for the U.S. The
provinces are shown on the USGS Geologic Radon Province Map (Figure 2). Each of the
geologic provinces was evaluated by examining the available data for that area: indoor radon
measurements, geology, aerial radioactivity, soil parameters, and foundation types. As stated
previously, these five factors are considered to be of basic importance in assessing radon
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potential and some data are available for each of these factors in every geologic province. The
province boundaries do not coincide with political borders (county and state) but define areas
of general radon potential. The five factors were assigned numerical values based on an
assessment of their respective contribution to radon potential, and a confidence level was
assigned to each contributing variable. The approach used by USGS to estimate the radon
potential for each province is described in Part II of this document.
EPA subsequently developed the Map of Radon Zones by extrapolating from the
province level to the county level so that all counties in the U.S. were assigned to one of
three radon zones. EPA assigned each county to a given zone based on its provincial radon
potential. For example, if a county is located within a geologic province that has a predicted
average screening level greater than 4 pCi/L, it was assigned to Zone 1. Likewise, counties
located in provinces with predicted average screening levels > 2 pCi/L and < 4 pCi/L, and
less than 2 pCi/L, were assigned to Zones 2 and 3, respectively.
If the boundaries of a county fall in more than one geologic province, the county was
assigned to a zone based on the predicted radon potential of the province in which most of
the area lies. For example, if three different provinces cross through a given county, the
county was assigned to the zone representing the radon potential of the province containing
most of the county's land area. (In this case, it is not technically correct to say that the
predicted average screening level applies to the entire county since the county falls in
multiple provinces with differing radon potentials.)
Figures 3 and 4 demonstrate an example of how EPA extrapolated the county zone
designations for Nebraska from the USGS geologic province map for the State. As figure 3
shows, USGS has identified 5 geologic provinces for Nebraska. Most of the counties are
extrapolated "straight" from their corresponding provinces, but there are counties "partitioned"
by several provinces — for example, Lincoln County. Although Lincoln county falls in
multiple provinces, it was assigned to Zone 3 because most of its area falls in the province
with the lowest radon potential.
It is important to note that EPA's extrapolation from the province level to the
county level may mask significant "highs" and "lows" within specific counties. In other
words, within-county variations in radon potential are not shown on the Map of Radon
Zones. EPA recommends that users who may need to address specific within-county
variations in radon potential (e.g., local government officials considering the
implementation of radon-resistant construction codes) consult USGS' Geologic Radon
Province Map and the State chapters provided with this map for more detailed
information, as well as any locally available data.
Map Validation
The Map of Radon Zones is intended to represent a preliminary assessment of radon
potential for the entire United States. The factors that are used in this effort —indoor radon
data, geology, aerial radioactivity, soils, and foundation type — are basic indicators for radon
potential. It is important to note, however, that the map's county zone designations are not
"statistically valid" predictions due to the nature of the data available for these 5 factors at the
county level. In order to validate the map in light of this lack of statistical confidence, EPA
conducted a number of analyses. These analyses have helped EPA to identify the best
situations in which to apply the map, and its limitations.
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Figure 3
Geologic Radon Potential Provinces for Nebraska
Liacola Count y
till Uiitrilt Low
Figure 4
NEBRASKA - EPA Map of Radon Zones
Liacola Coaaty
Zeie 1 Zoic 2 Zoic 3
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One such analysis involved comparing county zone designations to indoor radon
measurements from the State/EPA Residential Radon Surveys (SRRS). Screening averages
for counties with at least 100 measurements were compared to the counties' predicted radon
potential as indicated by the Map of Radon Zones. EPA found that 72% of the county
screening averages were correctly reflected by the appropriate zone designations on the Map.
In all other cases, they only differed by 1 zone.
Another accuracy analysis used the annual average data from the National Residential
Radon Survey (NRRS). The NRRS indicated that approximately 6 million homes in the
United States have annual averages greater than or equal to 4 pd/L. By cross checking the
county location of the approximately 5,700 homes which participated in the survey, their
radon measurements, and the zone designations for these counties, EPA found that
approximately 3.8 million homes of the 5.4 million homes with radon levels greater than or
equal to 4 pCi/L will be found in counties designated as Zone 1. A random sampling of an
equal number of counties would have only found approximately 1.8 million homes greater
than 4 pCi/L. In other words, this analysis indicated that the map approach is three times
more efficient at identifying high radon areas than random selection of zone designations.
Together, these analyses show that the approach EPA used to develop the Map of
Radon Zones is a reasonable one. In addition, the Agency's confidence is enhanced by results
of the extensive State review process - the map generally agrees with the States' knowledge
of and experience in their own jurisdictions. However, the accuracy analyses highlight two
important points: the fact that elevated levels will be found in Zones 2 and 3, and that there
will be significant numbers of homes with lower indoor radon levels in all of the Zones. For
these reasons, users of the Map of Radon Zones need to supplement the Map with locally
available data whenever possible. Although all known "hot spots", i.e., localized areas of
consistently elevated levels, are discussed in the State-
specific chapters, accurately defining the boundaries of the "hot spots" on this scale of map is
not possible at this time. Also, unknown "hot spots" do exist.
The Map of Radon Zones is intended to be a starting point for characterizing radon
potential because our knowledge of radon sources and transport is always growing. Although
this effort represents the best data available at this time, EPA will continue to study these
parameters and others such as house construction, ventilation features and meteorology factors
in order to better characterize the presence of radon in U.S homes, especially in high risk
areas. These efforts will eventually assist EPA in refining and revising the conclusions of the
Map of Radon Zones. And although this map is most appropriately used as a targeting tool
by the aforementioned audiences ~ the Agency encourages all residents to test their homes
for radon, regardless of geographic location or the zone designation of the county in
which they live. Similarly, the Map of Radon Zones should not to be used in lieu of
testing during real estate transactions.
Review Process
The Map of Radon Zones has undergone extensive review within EPA and outside the
Agency. The Association of American State Geologists (AASG) played an integral role in
this review process. The AASG individual State geologists have reviewed their State-specific
information, the USGS Geologic Radon Province Map, and other materials for their geologic
content and consistency.
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In addition to each State geologist providing technical comments, the State radon
offices were asked to comment on their respective States' radon potential evaluations. In
particular, the States were asked to evaluate the data used to assign their counties to specific
zones. EPA and USGS worked with the States to resolve any issues concerning county zone
designations. In a few cases, States have requested changes in county zone designations. The
requests were based on additional data from the State on geology, indoor radon
measurements, population, etc. Upon reviewing the data submitted by the States, EPA did
make some changes in zone designations. These changes, which do not strictly follow the
methodology outlined in this document, are discussed in the respective State chapters.
EPA encourages the States and counties to conduct further research and data collection
efforts to refine the Map of Radon Zones. EPA would like to be kept informed of any
changes the States, counties, or others make to the maps. Updates and revisions will be
handled in a similar fashion to the way the map was developed. States should notify EPA of
any proposed changes by forwarding the changes through the Regional EPA offices that are
listed in Part II. Depending on the amount of new information that is presented, EPA will
consider updating this map periodically. The State radon programs should initiate proper
notification of the appropriate State officials when the Map of Radon Zones is released and
when revisions or updates are made by the State or EPA.
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THE USGS/EPA RADON POTENTIAL ASSESSMENTS: AN INTRODUCTION
by
Linda C.S. Gundersen and R. Randall Schumann
U.S. Geological Survey
and
Sharon W. White
U.S. Environmental Protection Agency
BACKGROUND
The Indoor Radon Abatement Act of 1988 (15 U.S.C. 2661-2671) directed the U.S.
Environmental Protection Agency (EPA) to identify areas of the United States that have the
potential to produce harmful levels of indoor radon. These characterizations were to be based
on both geological data and on indoor radon levels in homes and other structures. The EPA
also was directed to develop model standards and techniques for new building construction
that would provide adequate prevention or mitigation of radon entry. As part of an
Interagency Agreement between the EPA and the U.S. Geological Survey (USGS), the USGS
has prepared radon potential estimates for the United States. This report is one of ten
booklets that document this effort. The purpose and intended use of these reports is to help
identify areas where states can target their radon program resources, to provide guidance in
selecting the most appropriate building code options for areas, and to provide general
information on radon and geology for each state for federal, state, and municipal officials
dealing with radon issues. These reports are not intended to be used as a substitute for
indoor radon testing, and they cannot and should not be used to estimate or predict the
indoor radon concentrations of individual homes, building sites, or housing tracts. Elevated
levels of indoor radon have been found in every State, and EPA recommends that all homes
be tested for indoor radon.
Booklets detailing the radon potential assessment for the U.S. have been developed for
each State. USGS geologists are the authors of the geologic radon potential booklets. Each
booklet consists of several components, the first being an overview to the mapping project
(Part I), this introduction to the USGS assessment (Part II), including a general discussion of
radon (occurrence, transport, etc.), and details concerning the types of data used. The third
component is a summary chapter outlining the general geology and geologic radon potential
of the EPA Region (Part III). The fourth component is an individual chapter for each state
(Part IV). Each state chapter discusses the state's specific geographic setting, soils, geologic
setting, geologic radon potential, indoor radon data, and a summary outlining the radon
potential rankings of geologic areas in the state. A variety of maps are presented in each
chapter—geologic, geographic, population, soils, aerial radioactivity, and indoor radon data by
county. Finally, the booklets contain EPA's map of radon zones for each state and an
accompanying description (Part V).
Because of constraints on the scales of maps presented in these reports and because the
smallest units used to present the indoor radon data are counties, some generalizations have
been made in order to estimate the radon potential of each area. Variations in geology, soil
characteristics, climatic factors, homeowner lifestyles, and other factors that influence radon
concentrations can be quite large within any particular geologic area, so these reports cannot
be used to estimate or predict the indoor radon concentrations of individual homes or housing
II-l Reprinted from USGS Open-File Report 93-292
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tracts. Within any area of a given geologic radon potential ranking, there are likely to be
areas where the radon potential is lower or higher than that assigned to the area as a whole,
especially in larger areas such as the large counties in some western states.
In each state chapter, references to additional reports related to radon are listed for the
state, and the reader is urged to consult tuese repon., tor more detailed information. In most
cases the best sources of information on radon for specific areas are state and local
departments of health, state departments responsible for nuclear safety or environmental
protection, and U.S. EPA regional offices. More detailed information on state or local
geology may be obtained from the state geological surveys. Addresses and telephone
numbers of state radon contacts, geological surveys, and EPA regional offices are listed in
Appendix C at the end of this chapter.
RADON GENERATION AND TRANSPORT IN SOILS
Radon (™Rn) is produced from the radioactive decay of radium (~6Ra), which is, in turn,
a product of the decay of uranium (~'8U) (fig. 1). The half-life of :"Rn is 3.825 days. Other
isotopes of radon occur naturally, but, with the exception of thoron ("°Rn), which occurs in
concentrations high enough to be of concern in a few localized areas, they are less important
in terms of indoor radon risk because of their extremely short half-lives and less common
occurrence. In general, the concentration and mobility of radon in soil are dependent on
several factors, the most important of which are the soil's radium content and distribution,
porosity, permeability to gas movement, and moisture content. These characteristics are, in
turn, determined by the soil's parent-material composition, climate, and. the soil's age or
maturity. If parent-material composition, climate, vegetation, age of the soil, and topography
are known, the physical and chemical properties of a soil in a given area can be predicted.
As soils form, they develop distinct layers, or horizons, that are cumulatively called the
soil profile. The A horizon is a surface or near-surface horizon containing a relative
abundance of organic matter but dominated by mineral matter. Some soils contain an E
horizon, directly below the A horizon, that is generally characterized by loss of clays, iron, or
aluminum, and has a characteristically lighter color than the A horizon. The B horizon
underlies the A or E horizon. Important characteristics of B horizons include accumulation of
clays, iron oxides, calcium carbonate or other soluble salts, and organic matter complexes. In
drier environments, a horizon may exist within or below the B horizon that is dominated by
calcium carbonate, often called caliche or calcrete. This carbonate-cemented horizon is
designated the K horizon in modern soil classification schemes. The C horizon underlies the
B (or K) and is a zone of weathered parent material that does not exhibit characteristics of A
or B horizons; that is, it is generally not a zone of leaching or accumulation. In soils formed
in place from the underlying bedrock, the C horizon is a zone of unconsolidated, weathered
bedrock overlying the unweathered bedrock.
The shape and orientation of soil particles (soil structure) control permeability and affect
water movement in the soil. Soils with blocky or granular structure have roughly equivalent
permeabilities in the horizontal and vertical directions, and air and water can infiltrate the soil
relatively easily. However, in soils with platy structure, horizontal permeability is much
greater than vertical permeability, and air and moisture infiltration is generally slow. Soils
with prismatic or columnar structure have dominantly vertical permeability. Platy and
prismatic structures form in soils with high clay contents. In soils with shrink-swell clays, air
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and moisture infiltration rates and depth of wetting may be limited when the cracks in the
surface soil layers swell shut. Clay-rich B horizons, particularly those with massive or platy
structure, can form a capping layer that impedes the escape of soil gas to the surface
(Schumann and others, 1992). However, the shrinkage of clays can act to open or widen
cracks upon drying, thus increasing the soil's permeability to gas flow during arier periods.
Radon transport in soils occurs by two processes: (1) diffusion and (2) flow (Tanner,
1964). Diffusion is the process whereby radon atoms move from areas of higher
concentration to areas of lower concentration in response to a concentration gradient. Flow is
the process by which soil air moves through soil pores in response to differences in pressure
within the soil or between the soil and the atmosphere, carrying the radon atoms along with it.
Diffusion is the dominant radon transport process in soils of low permeability, whereas flow
tends to dominate in highly permeable soils (Sextro and others, 1987). In low-permeability
soils, much of the radon may decay before it is able to enter a building because its transport
rate is reduced. Conversely, highly permeable soils, even those that are relatively low in
radium, such as those derived from some types of glacial deposits, have been associated with
high indoor radon levels in Europe and in the northern United States (Akerblom and others,
1984; Kunz and others, 1989; Sextro and others, 1987). In areas of karst topography formed
in carbonate rock (limestone or dolomite) environments, solution cavities and fissures can
increase soil permeability at depth by providing additional pathways for gas flow.
Not all radium contained in soil grains and grain coatings will result in mobile radon
when the radium decays. Depending on where the radium is distributed in the soil, many of
the radon atoms may remain imbedded in the soil grain containing the parent radium atom, or
become imbedded in adjacent soil grains. The portion of radium that releases radon into the
pores and fractures of rocks and soils is called the emanating fraction. When a radium atom
decays to radon, the energy generated is strong enough to send the radon atom a distance of
about 40 nanometers (1 nm = 10's meters), or about 2x10-" inches—this is known as alpha
recoil (Tanner, 1980). Moisture in the soil lessens the chance of a recoiling radon atom
becoming imbedded in an adjacent grain. Because water is more dense than air, a radon atom
will travel a shorter distance in a water-filled pore than in an air-filled pore, thus increasing
the likelihood that the radon atom will remain in the pore space. Intermediate moisture levels
enhance radon emanation but do not significantly affect permeability. However, high
moisture levels can significantly decrease the gas permeability of the soil and impede radon
movement through the soil.
Concentrations of radon in soils are generally many times higher than those inside of
buildings, ranging from tens of pCi/L to more than 100,000 pCi/L, but typically in the range
of hundreds to low thousands of pCi/L. Soil-gas radon concentrations can vary in response to
variations in climate and weather on hourly, daily, or seasonal time scales. Schumann and
others (1992) and Rose and others (1988) recorded order-of-magnitude variations in soil-gas
radon concentrations between seasons in Colorado and Pennsylvania. The most important
factors appear to be (1) soil moisture conditions, which are controlled in large part by
precipitation; (2) barometric pressure; and (3) temperature. Washington and Rose (1990)
suggest that temperature-controlled partitioning of radon between water and gas in soil pores
also has a significant influence on the amount of mobile radon in soil gas.
Homes in hilly limestone regions of the southern Appalachians were found to have higher
indoor radon concentrations during the summer than in the winter. A suggested cause for this
phenomenon involves temperature/pressure-driven flow of radon-laden air from subsurface
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solution cavities in the carbonate rock into houses. As warm air enters solution cavities that
are higher on the hilislope than the homes, it cools and settles, pushing radon-laden air from
lower in the cave or cavity system into structures on the hilislope (Gammage.and others,
1993). In contrast, homes built over caves having openings situated below the level of the
home had higher indoor radon levels in the winter, caused by cooler outside air entering the
cave, driving radon-laden air into cracks and solution cavities in the rock and soil, and *
ultimately, into homes (Gammage and others, 1993).
RADON ENTRY INTO BUILDINGS
A driving force (reduced atmospheric pressure in the house relative to the soil producing
a pressure gradient) and entry points must exist for radon to enter a building from'the soil
The negative pressure caused by furnace combustion, ventilation devices, and the stack effect
(the rising and escape of warm air from the upper floors of the building, causing a
temperature and pressure gradient within the structure) during cold winter months are
common driving forces. Cracks and other penetrations through building foundations, sump
holes, and slab-to-foundation wall joints are common entry points.
Radon levels in the basement are generally higher than those on the main floor or unper
floors of most structures. Homes with basements generally provide more entry points for
radon, commonly have a more pronounced stack effect, and typically have lower air pressure
relative to the surrounding soil than nonbasement homes. The term "nonbasement" applies to
slab-on-grade or crawl space construction.
METHODS AND SOURCES OF DATA
The assessments of radon potential in the booklets that follow this introduction were
made using five main types of data: (1) geologic (lithologic); (2) aerial radiometric; (3) soil
characteristics, including soil moisture, permeability, and drainage characteristics; (4) indoor
radon data; and (5) building architecture (specifically, whether homes in each area are built
slab-on-grade or have a basement or crawl space). These five factors were evaluated and
integrated to produce estimates of radon potential. Field measurements of soil-gas radon or
soil radioactivity were not used except where such data were available in existing published
reports of local field studies. Where applicable, such field studies are described in the
individual state chapters.
GEOLOGIC DATA
The types and distribution of lithologic units and other geologic features in an-
assessment area are of primary importance in determining radon potential. Rock types that
are most likely to cause indoor radon problems include carbonaceous black shales, glauconite-
beanng sandstones, certain kinds of fluvial sandstones and fluvial sediments, phosphorites
chalk, karst-producing carbonate rocks, certain kinds of glacial deposits, bauxite, uranium-rich
granitic rocks, metamorphic rocks of granitic composition, silica-rich volcanic rocks, many
sheared or faulted rocks, some coals, and certain kinds of contact metamorphosed rocks.
Rock types least likely to cause radon problems include marine quartz sands, non-
carbonaceous shales and siltstones, certain kinds of clays, silica-poor metamorphic and
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igneous rocks, and basalts. Exceptions exist within these general lithologic groups because of
the occurrence of localized uranium deposits, commonly of the hydrothermal type in
crystalline rocks or the "roll-front" type in sedimentary rocks. Uranium and radium are
commonly sited in heavy minerals, iron-oxide coatings on rock and soil grains, and organic
materials in soils and sediments. Less common are uranium associated with phosphate and
carbonate complexes in rocks and soils, and uranium minerals.
Although many cases of elevated indoor radon levels can be traced to high radium and
(or) uranium concentrations in parent rocks, some structural features, most notably faults and
shear zones, have been identified as sites of localized uranium concentrations (Deffeyes and
MacGregbr, 1980) and have been associated with some of the highest reported indoor radon
levels (Gundersen, 1991). The two highest known indoor radon occurrences are associated
with sheared fault zones in Boyertown, Pennsylvania (Gundersen and others, 1988a; Smith
and others, 1987), and in Clinton, New Jersey (Henry and others, 1991; Muessig and Bell,
1988).
NUKE AERIAL RADIOMETRIC DATA
Aerial radiometric data are used to quantify the radioactivity of rocks and soils.
Equivalent uranium (eU) data provide an estimate of the surficial concentrations of radon
parent materials (uranium, radium) in rocks and soils. Equivalent uranium is calculated from
the counts received by a gamma-ray detector from the 1.76 MeV (mega-electron volts)
emission energy corresponding to bismuth-214 (;"Bi), with the assumption that uranium and
its decay products are in secular equilibrium. Equivalent uranium is expressed in units of
parts per million (ppm). Gamma radioactivity also may be expressed in terms of a radium
activity; 3 ppm eU corresponds to approximately 1 picocurie per gram (pCi/g) of radium-226.
Although radon is highly mobile in soil and its concentration is affected by meteorological
conditions (Kovach, 1945; Klusman and Jaacks, 1987; Schery and others, 1984; Schumann
and others, 1992), statistical correlations between average soil-gas radon concentrations and
average eU values for a wide variety of soils have been documented (Gundersen and others,
1988a, 1988b; Schumann and Owen, 1988). Aerial radiometric data can provide an estimate
of radon source strength over a region, but the amount of radon that is able to enter a home
from the soil is dependent on several local factors, including soil structure, grain size
distribution, moisture content, and permeability, as well as type of house construction and its
structural condition.
The aerial radiometric data used for these characterizations were collected as part ot the
Department of Energy National Uranium Resource Evaluation (NURE) program of the 1970s
and early 1980s. The purpose of the NURE program was to identify and describe areas in the
United States having potential uranium resources (U.S. Department of Energy, 1976). The
NURE aerial radiometric data were collected by aircraft in which a gamma-ray spectrometer
was mounted flying approximately 122 m (400 ft) above the ground surface. The equivalent
uranium maps presented in the state chapters were generated from reprocessed NURE data in
which smoothing, filtering, recalibrating, and matching of adjacent quadrangle data sets were
performed to compensate for background, altitude, calibration, and other types of errors and
inconsistencies in the original data set (Duval and others, 1989). The data were then gridded
and contoured to produce maps of eU with a pixel size corresponding to approximately 2.5 x
2.5 km (1.6 x 1.6 mi).
II-6 Reprinted from USGS Open-File Report 93-292
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FLIGHT LINE SPICING OF SUKE AEKUL SURVEYS
2 rv (I MILE)
5 IU (3 HUES)
2 k 5 EH
E3 10 111 (6 HUES)
5 & 10 IH
NO Dili
Figure 2. Nominal flightline spacings for NURE aerial gamma-ray surveys covering the
contiguous United States (from Duval and others, 1990). Rectangles represent I°x2° quadrangles.
-------
-------
«
Figure 2 is an index map of NURE 1° x 2° quadrangles showing the flight-line spacing
for each quadrangle. In general, the more closely spaced the flightlines are, the more area
was covered by the aerial gamma survey, and thus, more detail is available in the data set.
For an altitude of 400 ft above the ground surface and with primary flightline spacing
typically between 3 and 6 miles, less than 10 percent of the ground surface of the United
States was actually measured by the airborne gamma-ray detectors (Duval and others, 1989),
although some areas had better coverage than others due to the differences in flight-line
spacing between areas (fig. 2). This suggests that some localized uranium anomalies may not
have been detected by the aerial surveys, but the good correlations of eU patterns with
geologic outcrop patterns indicate that, at relatively small scales (approximately 1:1,000,000
or smaller) the National eU map (Duval and others, 1989) gives reasonably good estimates of
average surface uranium concentrations and thus can assist in the prediction of radon potential
of rocks and soils, especially when augmented with additional geologic and soil data.
The shallow (20-30 cm) depth of investigation of gamma-ray spectrometers, either
ground-based or airborne (Duval and others, 1971; Durrance, 1986), suggests that gamma-ray
data may sometimes underestimate the radon-source strength in soils in which some of the
radionuclides in the near-surface soil layers have been transported downward through the soil
profile. In such cases the concentration of radioactive minerals in the A horizon would be
lower than in the B horizon, where such minerals are typically concentrated. The
concentration of radionuclides in the C horizon and below may be relatively unaffected by
surface solution processes. Under these conditions the surface gamma-ray signal may indicate
a lower radon source concentration than actually exists in the deeper soil layers, which are
most likely to affect radon levels in structures with basements. The redistribution of
radionuclides in soil profiles is dependent on a combination of climatic, geologic, and
geochemical factors. There is reason to believe that correlations of eU with actual soil
radium and uranium concentrations at a depth relevant to radon entry into structures may be
regionally variable (Duval, 1989; Schumann and Gundersen, 1991). Given sufficient
understanding of the factors cited above, these regional differences may be predictable.
SOIL SURVEY DATA
Soil surveys prepared by the U.S. Soil Conservation Service (SCS) provide data on soil
characteristics, including soil-cover thickness, grain-size distribution, permeability, shrink-
swell potential, vegetative cover, generalized groundwater characteristics, and land use. The
reports are available in county formats and State summaries. The county reports typically
contain both generalized and detailed maps of soils in the area.
Because of time and map-scale constraints, it was impractical to examine county soil
reports for each county in the United States, so more generalized summaries at appropriate
scales were used where available. For State or regional-scale radon characterizations, soil
maps were compared to geologic maps of the area, and the soil descriptions, shrink-swell
potential, drainage characteristics, depth to seasonal high water table, permeability, and other
relevant characteristics of each soil group noted. Technical soil terms used in soil surveys are
generally complex; however, a good summary of soil engineering terms and the national
distribution of technical soil types is the "Soils" sheet of the National Atlas (U.S. Department
of Agriculture, 1987).
II-8 Reprinted from USGS Open-File Report 93-292
-------
-------
Soil permeability is commonly expressed in SCS soil surveys in terms of the speed, in
inches per hour (in/hr), at which water soaks into the soil, as measured in a soil percolation
test. Although in/hr are not truly units of permeability, these units are in widespread use and
are referred to as "permeability" in SCS soil surveys. The permeabilities listed in the SCS
surveys are for water, but they generally correlate well with gas permeability. Because data
on gas permeability of soils is extremely limited, data on permeability to water is used as a
substitute except in cases in which excessive soil moisture is known to exist. Water in soil
pores inhibits gas transport, so the amount of radon available to a home is effectively reduced
by a high water table. Areas likely to have high water tables include river valleys, coastal
areas, and some areas overlain by deposits of glacial origin (for example, loess).
Soil permeabilities greater than 6.0 in/hr may be considered high, and permeabilities less
than 0.6 in/hr may be considered low in terms of soil-gas transport. Soils with low
permeability may generally be considered to have a lower radon potential than more
permeable soils with similar radium concentrations. Many well-developed soils contain a
clay-rich B horizon that may impede vertical soil gas transport. Radon generated below this
horizon cannot readily escape to the surface, so it would instead tend to move laterally,
especially under the influence of a negative pressure exerted by.a building.
Shrink-swell potential is an indicator of the abundance of smectitic (swelling) clays in a
soil. Soils with a high shrink-swell potential may cause building foundations to crack,
creating pathways for radon entry into the structure. During dry periods, desiccation cracks in
shrink-swell soils provide additional pathways for soil-gas transport and effectively increase
the gas permeability of the soil. Soil permeability data and soil profile data thus provide
important information for regional radon assessments.
INDOOR RADON DATA
Two major sources of indoor radon data were used. The first and largest source of data is
from the State/EPA Residential Radon Survey (Ronca-Battista and others, 1988; Dziuban and
others, 1990). Forty-two states completed EPA-sponsored indoor radon surveys between 1986
and 1992 (fig. 3). The State/EPA Residential Radon Surveys were designed to be
comprehensive and statistically significant at the state level, and were subjected to high levels
of quality assurance and control.' The surveys collected screening indoor radon measurements,
defined as 2-7 day measurements using charcoal canister radon detectors placed in the lowest
livable area of the home. The target population for the surveys included owner-occupied
single family, detached housing units (White and others, 1989), although attached structures
such as duplexes, townhouses, or condominiums were included in some of the surveys if they
met the other criteria and had contact with the ground surface. Participants were selected
randomly from telephone-directory listings. In total, approximately 60,000 homes were tested
in the State/EPA surveys.
The second source of indoor radon data comes from residential surveys that have been
conducted in a specific state or region of the country (e.g. independent state surveys or utility
company surveys). Several states, including Delaware, Florida, Illinois, New Hampshire, New
Jersey, New York, Oregon, and Utah, have conducted their own surveys of indoor radon. The
quality and design of a state or other independent survey are discussed and referenced where
the data are used.
II-9 Reprinted from USGS Open-File Report 93-292
-------
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Data for only those counties with five or more measurements are shown in the indoor
radon maps in the state chapters, although data for all counties with a nonzero number of
measurements are listed in the indoor radon data tables in each state chapter. In total, indoor
radon data from more than 100,000 homes nationwide were used in the compilation of these
assessments. Radon data from State or regional indoor radon surveys, public health
organizations, or other sources are discussed in addition to the primary data sources where
they are available. Nearly all of the data used in these evaluations represent short-term (2-7
day) screening measurements from the lowest livable space of the homes. Specific details
concerning the nature and use of indoor radon data sets other than the State/EPA Residential
Radon Survey are discussed in the individual State chapters.
RADON INDEX AND CONFIDENCE INDEX
Many of the geologic methods used to evaluate an area for radon potential require
subjective opinions based on the professional judgment and experience of the individual
geologist. The evaluations are nevertheless based on established scientific principles that are
universally applicable to any geographic area or geologic setting. This section describes the
methods and conceptual framework used by the U.S. Geological Survey to evaluate areas for
radon potential based on the five factors discussed in the previous sections. The scheme is
divided into two basic parts, a Radon Index (RI), used to rank the general radon potential of
the area, and the Confidence Index (CI), used to express the level of confidence in the
prediction based on the quantity and quality of the data used to make the determination. This
scheme works best if the areas to be evaluated are delineated by geologically-based
boundaries (geologic provinces) rather than political ones (state/county boundaries) in which
the geology may vary across the area.
Radon Index. Table 1 presents the Radon Index (RI) matrix. The five factors—indoor
radon data, geology, aerial radioactivity, soil parameters, and house foundation type—were
quantitatively ranked (using a point value of 1, 2, or 3) for their respective contribution to
radon potential in a given area. At least some data for the 5 factors are consistently available
for every geologic province. Because each of these main factors encompass a wide variety of
complex and variable components, the geologists performing the evaluation relied heavily on
their professional judgment and experience in assigning point values to each category and in
determining the overall radon potential ranking. Background information on these factors is
discussed in more detail in the preceding sections of this introduction.
Indoor radon was evaluated using unweighted arithmetic means of the indoor radon data
for each geologic area to be assessed. Other expressions of indoor radon levels in an area
also could have been used, such as weighted averages or annual averages, but these types of
data were not consistently available for the entire United States at the time of this writing, or
the schemes were not considered sufficient to provide a means of consistent comparison
across all areas. For this report, charcoal-canister screening measurement data from the
State/EPA Residential Radon Surveys and other carefully selected sources were used, as
described in the preceding section. To maintain consistency, other indoor radon data sets
(vendor, state, or other data) were not considered in scoring the indoor radon factor of the
Radon Index if they were not randomly sampled or could not be statistically combined with
the primary indoor radon data sets. However, these additional radon data sets can provide a
means to further refine correlations between geologic factors and radon potential, so they are
II-11 Reprinted from USGS Open-File Report 93-292
-------
TABLE 1. RADON INDEX MATRIX, "ppm eU" indicates parts per million of equivalent
uranium, as indicated by NURE aerial radiometric data. See text discussion for details.
FACTOR
INDOOR RADON (average)
AERIAL RADIOACTIVITY
GEOLOGY*
SOIL PERMEABILITY
ARCHTIECTURETYPE
POINT VALUE
1
<2pCi/L
< 1.5 ppm eU
mostly slab
2
•••••••••MBH^
2-4pCi/L
1.5 - 2.5 ppm eU
variable
moderate
mixed
3
>4pCi/L
> 2.5 ppm eU
positive
high
mostly basement
'GEOLOGIC FIELD EVIDENCE (GFE) POINTS: GFE points are assigned in addition to points
for the "Geology" factor for specific, relevant geologic field studies. See text for details.
Geologic evidence supporting: HIGH radon +2 points
MODERATE +1 point
LOW -2 points
No relevant geologic field studies 0 points
SCORING:
ategory
Probable average screening
Point ranpe indoor radon for area
LOW
MODERATE/VARIABLE
HIGH
3-8 points
9-11 points
12-17 points
>4pCi/L
POSSIBLE RANGE OF POINTS = 3 to 17
TABLE 2. CONFIDENCE INDEX MATRIX
INCREASING CONFIDENCE
FACTOR
•••••^•••M
INDOOR RADON DATA
AERIAL RADIOACTIVITY
••••••••^••"••••"^•^^••"•i^""""™^"^^"'"11^"
GEOLOGIC DATA
SOIL PERMEABILITY
POINT VALUE
sparse/no data
questionable/no data
quesuonaoie/no data
fair coverage/quality good coverage/quality
glacial cover
variable
variable
3
no glacial cover
proven geol. model
reliable, abundant
SCORING:
LOW CONFIDENCE
MODERATE CONFIDENCE
HIGH CONFIDENCE
4-6 points
7-9 points
10 -12 points
POSSIBLE RANGE OF POINTS = 4 to 12
H-12 Reprinted from USGS Open-File Report 93-292
-------
included as supplementary information and are discussed in the individual State chapters. If.
the average screening indoor radon level for an area was less than 2 pCi/L, the indoor radon
factor was assigned 1 point, if it was between 2 and 4 pCi/L, it was scored 2 points, and if
the average screening indoor radon level
-------
been leached from the upper soil layers but are present and possibly even concentrated in
deeper soil horizons, generating significant soil-gas radon. This positive supporting field
evidence adds two GFE points to the score, which helps to counteract the invalid conclusion
.u.,gested by the radiometric data. No GFE points re awarded if there are nc documented
field studies for the area.
"Soil permeability" refers to several soil characteristics that influence radon concentration
and mobility, including soil type, grain size, structure, soil moisture, drainage, slope, and
permeability. In the matrix, "low" refers to permeabilities less than about 0.6 in/hr; "high"
corresponds to greater than about 6.0 in/hr, in U.S. Soil Conservation Service (SCS) standard
soil percolation tests. The SCS data are for water permeability, which generally correlates
well with the gas permeability of the soil except when the soil moisture content is very high.
Areas with consistently high water tables were thus considered to have low gas permeability.
"Low, "moderate", and "high" permeability were assigned 1, 2, and 3 points, respectively.
Architecture type refers to whether homes in the area have mostly basements (3 points),
mostly slab-on-grade construction (1 point), or a mixture of the'two. Split-level and crawl
space homes fall into the "mixed" category (2 points). Architecture information is necessary
to properly interpret the indoor radon data and produce geologic radon potential categories
that are consistent with screening indoor radon data.
The overall RI for an area is calculated by adding the individual RI scores for the 5
factors, plus or minus GFE points, if any. The total RI for an area falls in one of three
categories—low, moderate or variable, or high. The point ranges for the three categories were
determined by examining the possible combinations of points for the 5 factors and setting
rules such that a majority (3 of 5 factors) would determine the final score for the low and
high categories, with allowances for possible deviation from an ideal score by the other two
factors. The moderate/variable category lies between these two ranges. A total deviation of 3
points from the "ideal" score was considered reasonable to allow for natural variability of
factors—if two of the five factors are allowed to vary from the "ideal" for a category, they
can differ by a minimum of 2 (1 point different each) and a maximum of 4 points (2 points
different each). With "ideal" scores of 5, 10, and 15 points describing low, moderate, and
high geologic radon potential, respectively, an ideal low score of 5 points plus 3 points for
possible variability allows a maximum of 8 points in the low category. Similarly, an ideal
high score of 15 points minus 3 points gives a minimum of 12 points for the high category.
Note, however, that if both other factors differ by two points from the "ideal", indicating
considerable variability in the system, the total point score would lie in the adjacent (i.e.,
moderate/variable) category.
Confidence Index. Except for architecture type, the same factors were used to establish a
Confidence Index (CI) for the radon potential prediction for each area (Table 2). Architecture
type was not included in the confidence index because house construction data are icadily and
reliably available through surveys taken by agencies and industry groups including the
National Association of Home Builders, U.S. Department of Housing and Urban
Development, and the Federal Housing Administration; thus it was not considered necessary
11-14 Reprinted from USGS Open-File Report 93-292
-------
to question the quality or validity of these data. The other factors were scored on the basis of
the quality and quantity of the data used to complete the RI matrix.
Indoor radon data were evaluated based on the distribution and number of data points and
on whether the data were collected by random sampling (State/EPA Residential Radon Survey
or other state survey data) or volunteered vendor data (likely to be nonrandom and biased
toward population centers and/or high indoor radon levels). The categories listed in the CI
matrix for indoor radon data ("sparse or no data", "fair coverage or quality", and "good
coverage/quality") indicate the sampling density and statistical robustness of an indoor radon
data set. Data from the State/EPA Residential Radon Survey and statistically valid state
surveys were typically assigned 3 Confidence Index points unless the data were poorly
distributed or absent in the area evaluated.
Aerial radioactivity data are available for all but a few areas of the continental United
States and for part of Alaska. An evaluation of the quality of the radioactivity data was based
on whether there appeared to be a good correlation between the radioactivity and the actual
amount of uranium or radium available to generate mobile radon in the rocks and soils of the
area evaluated. In general, the greatest problems with correlations among eU, geology, and
soil-gas or indoor radon levels were associated with glacial deposits (see the discussion in a
previous section) and typically were assigned a 2-point Confidence Index score. Correlations
among eU, geology, and radon were generally sound in unglaciated areas and were usually
assigned 3 CI points. Again, however, radioactivity data in some unglaciated areas may have
been assigned fewer than 3 points, and in glaciated areas may be assigned only one point, if
the data were considered questionable or if coverage was poor.
To assign Confidence Index scores for the geologic data factor, rock types and geologic
settings for which a physical-chemical, process-based understanding of radon generation and
mobility exists were regarded as having "proven geologic models" (3 points); a high
confidence could be held for predictions in such areas. Rocks for which the processes are
less well known or for which data are contradictory were regarded as "variable" (2 points),
and those about which little is known or for which no apparent correlations have been found
were deemed "questionable" (1 point).
The soil permeability factor was also scored based on quality and amount of data. The
three categories for soil permeability in the Confidence Index are similar in concept, and
scored similarly, to those for the geologic data factor. Soil permeability can be roughly
estimated from grain size and drainage class if data from standard, accepted soil percolation
tests are unavailable; however, the reliability of the data would be lower than if percolation
test figures or other measured permeability data are available, because an estimate of this type
does not encompass all the factors that affect soil permeability and thus may be inaccurate in
some instances. Most published soil permeability data are for water; although this is
generally closely related to the air permeability of the soil, there are some instances when it
may provide an incorrect estimate. Examples of areas in which water permeability data may
not accurately reflect air permeability include areas with consistently high levels of soil
moisture, or clay-rich soils, which would have a low water permeability but may have a
11-15 Reprinted from USGS Open-File Report 93-292
-------
significantly higher air permeability when dry due to shrinkage cracks in the soil. These
additional factors were applied to the soil permeability factor when assigning the RI score, but
may have less certainty in some cases and thus would be assigned a lower CI score.
The Radon Index and Confidence Index give a general indication of the relative
contributions of the interrelated geologic factors influencing radon generation and transport in
rocks and soils, and thus, of the potential for elevated indoor radon levels to occur in a
particular area. However, because these reports are somewhat generalized to cover relatively
large areas of States, it is highly recommended that more detailed studies be performed in
local areas of interest, using the methods and general information in these booklets as a guide.
11-16 Reprinted from USGS Open-File Report 93-292
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REFERENCES CITED
Akerblom, G., Anderson, P., and davensjo, B., 1984, Soil gas radon-A source for indoor radon
daughters: Radiation Protection Dosimetry. v. 7. ^. 49.54.
Deffeyes, K.S., and MacGregor, LD., 1980, World uranium resources: Scientific American,
v. 242, p. 66-76.
Durrance, EM., 1986, Radioactivity in geology: Principles and applications: New York, N Y
Wiley and Sons, 441 p.
Duval, J.S., 1989, Radioactivity and some of its applications in geology: Proceedings of the
symposium on the application of geophysics to engineering and environmental problems
(SAGEEP), Golden, Colorado, March 13-16,1989: Society of Engineering and Mineral
Exploration Geophysicists, p. 1-61.
Duval, J.S., Cook, B.C., and Adams, J.A.S., 1971, Circle of investigation of an airborne
gamma-ray spectrometer: Journal of Geophysical Research, v. 76, p. 8466-8470.
Duval, J.S., Jones, WJ., Riggle, F.R., and Pitkin, J.A., 1989, Equivalent uranium map of
conterminous United States: U.S. Geological Survey Open-Hie Report 89-478,10 p.
Duval, J.S., Reimer, G.M., Schumann, R.R., Owen, D.E., and Otton, J.K., 1990, Soil-gas
radon compared to aerial and ground gamma-ray measurements at study sites near Greeley
and Fort Collins, Colorado: U.S. Geological Survey Open-File Report 90-648,42 p.
Dziuban, J.A., Clifford, M.A., White, S.B., Bergstein, J.W., and Alexander, B.V., 1990,
Residential radon survey of twenty-three States, in Proceedings of the 1990 International
Symposium on Radon and Radon Reduction Technology, Vol. EL Preprints: U.S.
Environmental Protection Agency report EPA/600/9-90/005c, Paper IV-2,17 p.
Gammage, R.B., Wilson, D.L., Saultz, RJ., and Bauer, B.C., 1993, Subtereanean transport of
radon and elevated indoor radon in hilly karst terrenes: Atmospheric Environment
(in press).
Gundersen, L.C.S., Reimer, G.M., and Agard, S.S., 1988a, Correlation between geology, radon
in soil gas, and indoor radon in the Reading Prong, in Marikos, M.A., and Hansman,
R.H., eds., Geologic causes of natural radionuclide anomalies: Missouri Department of
Natural Resources Special Publication 4, p. 91-102.
Gundersen, L.C.S, Reimer, G.M., Wiggs, C.R., and Rice, C.A., 1988b, Map showing radon
potential of rocks and soils in Montgomery County, Maryland: U.S. Geological Survey
Miscellaneous Field Studies Map MF-2043, scale 1:62,500.
Gundersen, Linda C.S., 1991, Radon in sheared metamorphic and igneous rocks, in Gundersen,
Linda C.S., and Richard B. Wanty, eds., Field studies of radon in rocks, soils, and water
U.S. Geol. Survey Bulletin no. 1971, p. 39-50.
JI-17 Reprinted from USGS Open-Hie Report 93-292
-------
Henry, Mitchell E., Kaeding, Margret E., and Monteverde, Donald, 1991, Radon in soil gas and
gamma-ray activity of rocks and soils at the Mulligan Quarry, Clinton, New Jersey, in
Gundersen, Linda C.S., and Richard B. Wanty, eds., Field studies of radon in rocks,
soils, and water: U.S. GeoL Survey Bulletin no. 1971, p. 65-75.
Klusman, R. W., and Jaacks, J. A., 1987, Environmental influences upon mercury, radon, and
helium concentrations in soil gases at a site near Denver, Colorado: Journal of
Geochemical Exploration, v. 27, p. 259-280.
s
Kovach, EJM, 1945, Meteorological influences upon the radon content of soil gas: Transactions,
American Geophysical Union, v. 26, p. 241-248.
Kunz, C, Laymon, C.A., and Parker, C., 1989, Gravelly soils and indoor radon, in Osborne,
M.C., and Harrison, J., eds., Proceedings of the 1988 EPA Symposium on Radon and
Radon Reduction Technology, Volume 1: U.S. Environmental Protection Agency Report
EPA/600/9-89/006A, p. 5-75-5-86.
Muessig, K., and BeH, C, 1988, Use of airborne radiometric data to direct testing for elevated
indoor radon: Northeastern Environmental Science, v. 7, no. 1, p. 45-51.
Ronca-Battista, M., Moon, M., Bergsten, J., White, S.B., Holt, N., and Alexander, B., 1988,
Radon-222 concentrations in the United States-Results of sample surveys in five states:
Radiation Protection Dosimetry, v. 24, p. 307-312.
Rose, A.W., Washington, J.W., and Greeman, D.J., 1988, Variability of radon with depth and
season in a central Pennsylvania soil developed on limestone: Northeastern Environmental
Science, v. 7, p. 35-39.
Schery, S.D., Gaeddert, D.H., and Wilkening, MIL, 1984, Factors affecting exhalation of radon
from a gravelly sandy loam: Journal of Geophysical Research, v. 89, p. 7299-7309.
Schumann, R.R., and Owen, D.E., 1988, Relationships between geology, equivalent uranium
concentration, and radon in soil gas, Fairfax County, Virginia: U.S. Geological Survey
Open-File Report 88-18,28 p.
Schumann, R.R., and Gundersen, L.C.S., 1991, Regional differences in radon emanation
coefficients in soils: Geological Society of America Abstracts With Programs, v. 23,
no. 1, p. 125.
Schumann, R.R., Peake, R.T., Schmidt, K.M., and Owen, DJE., 1991, Correlations of soil-gas
and indoor radon with geology in glacially derived soils of the northern Great Plains, m
Proceedings of the 1990 International Symposium on Radon and Radon Reduction
Technology, Volume 2, Symposium Oral Papers: U.S. Environmental Protection Agency
report EPA/600/9-91A)26b, p. 6-23-6-36.
n-18 Reprinted from USGS Open-Fife Report 93-292
-------
*
Schumann, RJEL, Owen, D.E., and Asher-Bolinder, S., 1992, Effects of weather and soil
characteristics on temporal variations in soil-gas radon concentrations, in Gates, A.E., and
Gundersen, L.C.S., eds., Geologic controls on radon: Geological Society of America
Special Paper 271, p. 65-72.
Sextro, R.G., Moed, B.A., Nazaroff, W.W., Revzan, K.L., and Nero, A.V., 1987,
Investigations of soil as a source of indoor radon, in Hopke, P.K., ed., Radon and its
decay products: American Chemical Society Symposium Series 331, p. 10-29.
Sterling, R., Meixel, G., Shen, L., Labs, K., and Bligh, T., 1985, Assessment of the energy
savings potential of building foundations research: Oak Ridge, Tenn., U.S. Department of
Energy Report ORNL/SUB/84-0024/1.
Smith, R.C., H, Reilly, M.A., Rose, A.W., Barnes, J.H., and Berkheiser, S.W., Jr., 1987,
Radon: a profound case: Pennsylvania Geology, v. 18, p. 1-7.
Tanner, A.B., 1964, Radon migration in the ground: a review, in Adams, J.A.S., and Lowder,
W.M., eds., The natural radiation environment: Chicago, EL, University of Chicago
Press, p. 161-190.
Tanner, A.B., 1980, Radon migration in the ground: a supplementary review, in Gesell, T.F.,
and Lowder, W.M. (eds), Natural radiation environment m, Symposium proceedings,'
Houston, Texas, v. 1, p. 5-56.
U.S. Department of Agriculture, 1987, Principal kinds of soils: Orders, suborders, and great
groups: U.S. Geological Survey, National Atlas of the United States of America, sheet
38077-BE-NA-07M-00, scale 1:7,500,000.
U.S. Department of Energy, 1976, National Uranium Resource Evaluation preliminary report,
prepared by the U.S. Energy Research and Development Administration, Grand Junction
Colo.: GJO-11(76).
Wanty, Richard B., and Schoen, Robert, 1991, A review of the chemical processes affecting the
mobility of radionuclides in natural waters, with applications, in Gundersen, Linda C.S.,
and Richard B. Wanty, eds., Field studies of radon in rocks, soils, and water: U.S.
Geological Survey Bulletin no. 1971, p. 183-194.
Washington, J.W., and Rose, A.W., 1990, Regional and temporal relations of radon in soil gas to
soil temperature and moisture: Geophysical Research Letters, v. 17, p. 829-832.
White, S.B., Bergsten, J.W., Alexander, B.V., and Ronca-Battista, M., 1989, Multi-State
surveys of indoor 222Rn: Health Physics, v. 57, p. 891-896.
n-19 Reprinted from USGS Open-File Report 93-292
-------
-------
APPENDIX A
GEOLOGIC TIME SCALE
Subdivisions (and their symbols)
Eon or
Eonothem
Phanerozoic9
Proterozoic
/PI
ICJ
Archean
(A)
Era or
Erathem
Cenozoic 2
(CD
Mesozoic2
(Mi)
Paleozoic3
(rz)
La>1*
. M*°°* ~
A**:;;™
Mioax
AfCfMBR (VI
t««v
Period. System.
Subperiod. Subsystem
Quaternary J
(Q)
Neocene 2
SusDeriod or
T.n!.fY SobtVKtm (N)
m Paieogene
Suoperiodor
Subsystem (Pi)
Cretaceous
(K)
Jurassic
U)
Triassic
Hi)
Permian
(P)
Pennsylvanian
Carboniferous (P)
1C) Mississtppian
(M)
Devonian
(D)
Silurian
fCI
(91
Ordovieian
m\
\Ol
Cambrian
(C)
Epoch or Series
Holocene
Pleistocene
Pliocene
Miocene
Oligocene
Eocene
Paleocene
Late
Early
Late
Middle
Early
Late
Middle
Early
Late
Early
Late
Middle
Early
Late
Early
Late
Middle
Early
Late
Middle
Early
Late
Middle
Early
Late
Middle
Early
Upper
Lower
Upper
Middle
Lower
Upper
Middle
Lower
Upper
Lower
Upper
Middle
Lower
Upper
Lower
Uooer
Middle
Lower
Upper
Middle
Lower
Upper
Middle
Lower
Upper
Middle
Lower
None defined
None defined
None defined
None defined
None defined
None defined
pr*>Are)M*n (pA) *
Age estimates
of boundaries
in mega-annum
(Ma)1
-570*
1 Range* reflect oncertaintie* of botopfe and bkwtrmtioraphie age aMignmentt. Age boundaries not cto»e)y bracketed
data shown by-. Decay constants and boiopic ratios employed are died in Steiger and Jlger (1977). Designation m.y. used for an
* Modifiers (tower, middle, upper or early, middle, late) when used wtth these hems are Informal divisions of the larger unit the
first toner of the modifier I* lowercase.
'Rocks older than 570 Ma also caned Precambrian (pC). a time term without specific rank.
'Informal time term without specific rank.
USGS Open-File Report 93-292
-------
-------
APPENDIX B
GLOSSARY OF TERMS
Units of measure
pCi/L (picocuries per liter)- a unit of measure of radioactivity used to describe radon
concentrations in a volume of air. One picocurie (10'12 curies) is equal to about 2.2 disintegrations
of radon atoms per minute. A liter is about 1.06 quarts. The average concentration of radon in
U.S. homes measured to date is between 1 and 2 pCS/L.
Bq/m3 (Becquerels per cubic meter)- a metric unit of radioactivity used to describe radon
concentrations in a volume of air. One becquerel is equal to one radioactive disintegration per
second. One pCS/L is equal to 37 Bq/m3.
ppm (parts per million)- a unit of measure of concentration by weight of an element in a
substance, in this case, soil or rock. One ppm of uranium contained in a ton of rock corresponds
to about 0.03 ounces of uranium. The average concentration of uranium in soils in the United
States is between 1 and 2 ppm.
in/hr (inches per hour)- a unit of measure used by soil scientists and engineers to describe the
permeability of a soil to water flowing through it It is measured by digging a hole 1 foot (12
inches) square and one foot deep, filling it with water, and measuring the time it takes for the water
to drain from the hole. The drop in height of the water level in the hole, measured in inches, is
then divided by the time (in hours) to determine the permeability. Soils range in permeability from
less than 0.06 in/hr to greater than 20 in/hr, but most soils in the United States have permeabilities
between these two extremes.
Geologic terms and terms related to the study of radon
aerial radiometric, aeroradiometric survey A survey of radioactivity, usually gamma rays,
taken by an aircraft carrying a gamma-ray spectrometer pointed at the ground surface.
alluvial fan A low, widespread mass of loose rock and soil material, shaped like an open fan
and deposited by a stream at the point where it flows from a narrow mountain valley out onto a
plain or broader valley. May also form at the junction with larger streams or when the gradient of
the stream abruptly decreases.
alluvium, alluvial General terms referring to unconsolidated detrital material deposited by a
stream or other body of running water.
alpha-track detector A passive radon measurement device consisting of a plastic film that is
sensitive to alpha particles. The film is etched with acid in a laboratory after it is exposed. The
etching reveals scratches, or "tracks", left by the alpha particles resulting from radon decay, which
can then be counted to calculate the radon concentration. Useful for long-term (1-12 months)
radon tests.
ampnibolite A mafic metamorphic rock consisting mainly of pyroxenes and(or) amphibole and
plagioclase.
11-21 Reprinted from USGS Open-Hie Report 93-292
-------
argillite, argillaceous Terms referring to a rock derived from clay or shale, or any sedimentary
rock containing an appreciable amount of clay-size material, Le., argillaceous sandstone.
arid Term describing a climate characterized by dryness, or an evaporation rate that exceeds the
amount of precipitation.
basalt A general term for a dark-colored mafic igneous rocks that may be of extrusive origin,
such as volcanic basalt flows, or intrusive origin, such as basalt dikes.
bathoHth A mass of plutonic igneous rock that has more than 40 square miles of surface
exposure and no known bottom.
carbonate A sedimentary rock consisting of the carbonate (COs) compounds of calcium,
magnesium, or iron, e.g. limestone and dolomite.
carbonaceous Said of a rock or sediment that is rich in carbon, is coaly, or contains organic
matter.
charcoal canister A passive radon measurement device consisting of a small container of
granulated activated charcoal that is designed to adsorb radon. Useful for short duration (2-7 days)
measurements only. May be referred to as a "screening" test
chert A hard, extremely dense sedimentary rock consisting dominantly of interlocking crystals of
quartz. Crystals are not visible to the naked eye, giving the rock a milky, dull luster. It may be
white or gray but is commonly colored red, black, yellow, blue, pink, brown, or green.
clastic pertaining to a rock or sediment composed of fragments mat are derived from preexisting
rocks or minerals. The most common clastic sedimentary rocks are sandstone and shale.
clay A rock containing clay mineral fragments or material of any composition having a diameter
less than 1/256 mm.
clay mineral One of a complex and loosely defined group of finely crystalline minerals made up
of water, silicate and aluminum (and a wide variety of other elements). They are formed chiefly by
alteration or weathering of primary silicate minerals. Certain clay minerals are noted for their small
size and ability to absorb substantial amounts of water, causing them to swell. The change in size
that occurs as these clays change between dry and wet is referred to as their "shrink-swell"
potential.
concretion A hard, compact mass of mineral matter, normally subspherical but commonly
irregular in shape; formed by precipitation from a water solution about a nucleus or center, such as
a leaf, shell, bone, or fossil, within a sedimentary or fractured rock.
conglomerate A coarse-grained, clastic sedimentary rock composed of rock and mineral
fragments larger than 2 mm, set in a finer-grained matrix of clastic material.
cuesta A hill or ridge with a gentle slope on one side and a steep slope on the other. The
formation of a cuesta is controlled by the different weathering properties and the structural dip of
the rocks forming the hill or ridge.
daughter product A nuclide formed by the disintegration of a radioactive precursor or "parent"
atom.
H-22 Reprinted from USGS Open-File Report 93-292
-------
delta, deltaic Referring to a low, fiat, alluvial tract of land having a triangular or fan shape
located at or near the mouth of a river. It results from the accumulation of sediment deposited by a
nver at the point at which the river loses its ability to transport the sediment, commonly where a
nver meets a larger body of water such as a lake or ocean.
dike A tabular igneous intrusion of rock, younger than the surrounding rock, that commonly cuts
across the bedding or foliation of the rock it intrudes.
diorite A plutonic igneous rock that is medium in color and contains visible dark minerals that
make up less than 50% of the rock. It also contains abundant sodium plagioclase and minor
quartz.
dolomite A carbonate sedimentary rock of which more than 50% consists of the mineral dolomite
), and is commonly white, gray, brown, yellow, or pinkish in color.
drainage The manner in which the waters of an area pass, flow off of, or flow into the soil
Also refers to the water features of an area, such as lakes and rivers, that drain it
eolian Pertaining to sediments deposited by the wind.
esker A long, narrow, steep-sided ridge composed of irregular beds of sand and gravel deposited
by streams beneath a glacier and left behind when the ice melted.
evapotranspiration Loss of water from a land area by evaporation from the soil and
transpiration from plants.
extrusive Said of igneous rocks that have been erupted onto the surface of the Earth.
fault A fracture or zone of fractures in rock or sediment along which there has been movement
fluvial, fluvial deposit Pertaining to sediment that has been deposited by a river or stream.
foliation A linear feature in a rock defined by both mineralogic and structural characteristics. It
may be formed during deformation or metamorphism.
formation A mappable body of rock having similar characteristics.
glacial deposit Any sediment transported and deposited by a glacier or processes associated
with glaciers, such as glaciofluvial sediments deposited by streams flowing from melting glaciers.
gneiss A rock formed by metamorphism in which bands and lenses of minerals of similar
composition alternate with bands and lenses of different composition, giving the rock a striped or
"foliated" appearance.
granite Broadly applied, any coarsely crystalline, quartz- and feldspar-bearing igneous plutonic
rock. Technically, granites have between 10 and 50% quartz, and alkali feldspar comprises at least
65% of the total feldspar.
gravel An unconsolidated, natural accumulation of rock fragments consisting predominantly of
particles greater than 2 mm in size.
heavy minerals Mineral grains in sediment or sedimentary rock having higher than average
specific gravity. May form layers and lenses because of wind or water sorting by weight and size
11-23 Reprinted from USGS Open-File Report 93-292
-------
and may be referred to as a "placer deposit" Some heavy minerals are magnetite, garnet, zircon,
monazite, and xenotime.
igneous Said of a rock or mineral that solidified from molten or partly molten rock material. It is
one of the three main classes into which rocks are divided, the others being sedimentary and
mctamorphic.
inter-montane A term that refers to an area between two mountains or mountain ranges.
intrusion, intrusive The processes of emplacement or injection of molten rock into pre-existing
rock. Also refers to the rock formed by intrusive processes, such as an "intrusive igneous rock .
kame A low mound, knob, hummock, or short irregular ridge formed by a glacial stream at the
margin of a melting glacier; composed of bedded sand and gravel.
karst terrain A type of topography that is formed on limestone, gypsum and other rocks by
dissolution of the rock by water, forming sinkholes and caves.
lignite A brownish-black coal that is intermediate in coalification between peat and
subbituminous coal.
limestone A carbonate sedimentary rock consisting of more than 50% calcium carbonate,
primarily in the form of the mineral calcite (CaCOs).
lithology The description of rocks in hand specimen and in outcrop on the basis of color,
composition, and grain size.
loam A permeable soil composed of a mixture of relatively equal parts clay, silt, and sand, and
usually containing some organic matter.
loess A fine-grained eolian deposit composed of silt-sized particles generally thought to have
been deposited from windblown dust of Pleistocene age.
mafic Term describing an igneous rock containing more man 50% dark-colored minerals.
marine Term describing sediments deposited in the ocean, or precipitated from ocean waters.
metamorphic Any rock derived from pre-existing rocks by mineralogical, chemical, or structural
changes in response to changes in temperature, pressure, stress, and the chemical environment.
Phyllitc, schist, amphibolite, and gneiss are metamorphic rocks.
moraine A mound, ridge, or other distinct accumulation of unsorted, imbedded glacial material,
predominantly till, deposited by the action of glacial ice.
outcrop That part of a geologic formation or structure that appears at the surface of the Earth, as
in "rock outcrop".
percolation test A term used in engineering for a test to determine the water permeability of a
soil. A hole is dug and filled with water and the rate of water level decline is measured.
permeability The capacity of a rock, sediment, or soil to transmit liquid or gas.
phosphate, phosphatic, phosphorite Any rock or sediment containing a significant amount
of phosphate minerals, Le., minerals containing PO4.
n-24 Reprinted from USGS Open-File Report 93-292
-------
physiographic province A region in which all parts are similar in geologic 'structure and
climate, which has had a uniform geomorphic history, and whose topography or landforms differ
significantly from adjacent regions.
placer deposit See heavy minerals
residual Formed by weathering of a material in place.
residuum Deposit of residual material.
rhyolite An extrusive igneous rock of volcanic origin, compositionally equivalent to granite.
sandstone A clastic sedimentary rock composed of sand-sized rock and mineral material that is
more or less firmly cemented. Sand particles range from 1/16 to 2 mm in size.
^Lt^fl f°Sated .cryst?Uine *ock>foimed by metamorphism, that can be readily split into
thin flakes or slabs. Contains mica; minerals are typically aligned.
screening level Result of an indoor radon test taken with a charcoal canister or similar device
for a shortperiod of time, usually less than seven days. May indicate the potential for an indoor'
radon problem but does not indicate annual exposure to radon.
sediment Deposits of rock and mineral particles or fragments originating from material that is
JJSSE? y **'WEter OT Ke' °r that accumulate by natural chemical precipitation or secretion of
organisms.
semiarid Refers to a climate that has slightly more precipitation than an arid climate.
shale A fine-grained sedimentary rock formed from solidification (lithification) of clay or mud.
shear zone Refers to a roughly linear zone of rock that has been faulted by ductile or non-ductile
processes in which the rock is sheared and both sides are displaced relative to one another.
shrink-swell clay See clay mineral.
siltstone A fine-grained clastic sedimentary rock composed of silt-sized rock and mineral
material and more or less firmly cemented. Silt particles range from 1/16 to 1/256 mm in size.
sinkhole A roughly circular depression in a karst area measuring meters to tens of meters in
diameter. It is funnel shaped and is formed by collapse of the surface material into an underlying
void created by the dissolution of carbonate rock.
slope An inclined part of the earth's surface.
solution cavity A hole, channel or cave-like cavity formed by dissolution of rock.
stratigraphy The study of rock strata; also refers to the succession of rocks of a particular area.
surficial materials Unconsolidated glacial, wind-, or waterborne deposits occurring on the
earth s surface.
tablelands General term for a broad, elevated region with a nearly level surface of considerable
extent.
n-25 Reprinted from USGS Open-File Report 93-292
-------
terrace gravel Gravel-sized material that caps ridges and terraces, left behind by a stream as it
cuts down to a lower level.
terrain A tract or region of the Earth's surface considered as a physical feature or an ecological
environment
till Unsorted, generally unconsolidated and imbedded rock and mineral material deposited directly
adjacent to and underneath a glacier, without reworking by meltwater. Size of grains varies greatly
from clay to boulders.
uraniferous Containing uranium, usually more than 2 ppm.
vendor data Used in this report to refer to indoor radon data collected and measured by
commercial vendors of radon measurement devices and/or services.
volcanic Pertaining to the activities, structures, and extrusive rock types of a volcano.
water table The surface forming the boundary between the zone of saturation and the zone of
aeration; the top surface of a body of unconfined groundwater in rock or soil
weathering The destructive process by which earth and rock materials, on exposure to
atmospheric elements, are changed in color, texture, composition, firmness, or form with little or
no transport of the material.
11-26 Reprinted from USGS Open-File Report 93-292
-------
APPENDIX C
EPA REGIONAL OFFICES
EPA Region 1
JFK Federal Building
Boston, MA 02203
(617) 565-4502
EPA Region 2
(2AIR:RAD)
26 Federal Plaza
New York, NY 10278
(212) 264-4110
Region 3 (3AH14)
841 Chestnut Street
Philadelphia, PA 19107
(215) 597-8326
EPA Region 4
345 Courtland Street, N.E.
Atlanta, GA 30365
(404) 347-3907
EPA Region 5 (5AR26)
77 West Jackson Blvd.
Chicago, IL 60604-3507
(312) 886-6175
EPA Region 6 (6T-AS)
1445 Ross Avenue
Dallas, TX 75202-2733
(214) 655-7224
EPA Region 7
726 Minnesota Avenue
Kansas City, KS 66101
(913) 551-7604
EPA Region 8
(8HWM-RP)
999 18th Street
One Denver Place, Suite 1300
Denver, CO 80202-2413
(303) 293-1713
EPA Region 9 (A-3)
75 Hawthorne Street
San Francisco, CA 94105
(415) 744-1048
EPA Region 10
1200 Sixth Avenue
Seattle, WA 98101
(202) 442-7660
State
Alabama
Alaska
Arizona
Arkansas
California
Colorado
Connecticut
Delaware
District of Columbia .
Florida
Georgia
Hawaii
Idaho
Illinois
Indiana
Iowa
Kansas •
Kentucky
Louisiana
Maine
Maryland
Massachusetts
Michigan
Minnesota
Mississippi
Missouri
Montana
Nebraska
Nevada
New Hampshire
New Jersey
New Mexico
New York
North Carolina ,
North Dakota
Ohio
Oklahoma ;
Oregon
Pennsylvania
Rhode Island
South Carolina
South Dakota....
Tennessee
Texas
Utah. .
Vermont.
Virginia
Washington
West Virginia
Wisconsin
Wyoming
4
1 A
6
9
1
3
4
4
5
7
4
6
1
3
1
5
5
....4
7
8
7
1
2
6
4
8
5
6
10
3
1
4
, 8
4
3
10
3
8
H-27 Reprinted from USGS Open-File Report 93-292
-------
STATE RADON CONTACTS
May, 1993
Alabama James McNees
Division of Radiation Control
Alabama Department of Public Health
State Office Building
Montgomery, AL 36130
(205)242-5315
1-800-582-1866 in state
Alaska Chalks Tedford
Department of Health and Social
Services
P.O. Box 110613
Juneau,AK 99811-0613
(907)465-3019
1-800-478-4845 in state
Arizona John Stewart
Arizona Radiation Regulatory Agency
4814 South 40th St
Phoenix, AZ 85040
(602)2554845
Aricansqs LeeGershner
Division of Radiation Control
Department of Health
4815 Markham Street, Slot 30
Little Rock, AR 72205-3867
(501)661-2301
California J. David Quinton
Department of Health Services
714 P Street, Room 600
Sacramento, CA 94234-7320
(916)324-2208
1-800-745-7236 in state
Colorado JJnda Martin
Department of Health
4210 East llth Avenue
Denver, CO 80220
(303)692-3057
1-800-846-3986 in state
Connecticut Alan J. Siniscalchi
Radon Program
Connecticut Department of Health
Services
150 Washington Street
Hartford, CT 061064474
(203)566-3122
Delaware MaraiG.Rejai
Office of Radiation Control
Division of Public Health
P.O. Box 637
Dover, DE 19903
(302)736-3028
1-800-554-4636 In State
District Robert Davis
of Columbia DC Department of Consumer and
Regulatory Afiairs
614 H Street NW
Room 1014
Washington, DC 20001
(202)727-71068
Honda N. Michael GiUey
Office of Radiation Control
Department of Health and
Rehabilitative Services
1317 Winewood Boulevard
Tallahassee, FL 32399-0700
(904)488-1525
1-800-543-8279 in state
Richard Schreiber
Georgia Department of Human
Resources
878 Peachtree St, Room 100
Atlanta, GA 30309
(404)894-6644
1-800-745-0037 in state
Hawaii Russell Takata
Environmental Health Services
Division
591 Ala Moana Boulevard
Honolulu, HI 96813-2498
(808)586-4700
11-28 Reprinted from USGS Open-File Report 93-292
-------
Idaho
Illinois
Iowa
Kansas
Kentucky
PatMcGavam
Office of Environmental Health
450 West State Street
Boise, ID 83720
(208)334-6584
1-800-445-8647 in state
Richard Allen
Illinois Department of Nuclear Safety
1301 Outer Park Drive
Springfield, IL 62704
(217) 524-5614
1-800-325-1245 in state
Lorand Magyar
Radiological Health Section
Indiana State Department of Health
1330 West Michigan Street
P.O. Box 1964
Indianapolis, IN 46206
(317)633-8563
1-800-272-9723 In State
Donald A. Plater
Bureau of Radiological Health
Iowa Department of Public Health
Lucas State Office Building
Des Moines, IA 50319-0075
(515)281-3478
1-800-383-5992 In State
Harold Spiker
Radiation Control Program
Kansas Department of Health and
Environment
109 SW 9th Street
6th Floor Mills Building
Topeka,KS 66612
(913)296-1561
JeanaPhelps
Radiation Control Branch
Department of Health Services
Cabinet for Human Resources
275 East Main Street
Frankfort, KY 40601
(502)564-3700
Louisiana Matt Schlenker
Louisiana Department of
Environmental Quality
P.O. Box 82135
Baton Rouge, LA 70884-2135
(504)925-7042
1-800-256-2494 in state
Mains BpbStilwell
Division of Health Engineering
Department of Human Services
State House, Station 10
Augusta, ME 04333
(207)289-5676
1-800-232-0842 in state
Maryland LeonJ. Rachuba
Radiological Health Program
Maryland Department of the
Environment
2500 Broening Highway
Baltimore, MD 21224
(410)631-3301
1-800-872-3666 In State
William J. Bell
Radiation Control Program
Department of Public Health
23 Service Center
Northampton, MA 01060
(413)586-7525
1-800-445-1255 in state
Michigan Sue Hendershott
Division of Radiological Health
Bureau of Environmental and
Occupational Health
3423 North Logan Street
P.O. Box 30195
Lansing, MI 48909
(517)335-8194
Minnesota Laura Oatmann
Indoor Air Quality Unit
925 Delaware Street, SE
P.O. Box 59040
Minneapolis, MN 55459-0040
(612)627-5480
1-800-798-9050 in state
n-29 Reprinted from USGS Open-File Report 93-292
-------
Mississii
issouri.
Montana
Silas Anderson
Division of Radiological Health
Department of Health
3150 Lawson Street
P.O. Box 1700
Jackson, MS 39215-1700
(601)354-6657
1-800-626-7739 in state
Kenneth V. Miller
Bureau of Radiological Health
Missouri Department of Health
1730 East Elm
P.O. Box 570
Jefferson City, MO 65102
(314)751-6083
1-800-669-7236 In State
Adrian C.Howe
Occupational Health Bureau
Montana Department of Health and
Environmental Sciences
Cogswell Building A113
Helena, MT 59620
(406)444-3671
Joseph Milone
Division of Radiological Health
Nebraska Department of Health
301 Centennial Mall, South
P.O. Box 95007
Lincoln, NK 68509
(402)471-2168
1-800-334-9491 In State
Stan Marshall
Department of Human Resources
505 East King Street
Room 203
Carson City,NV 89710
(702) 687-5394
New Hampshire David Chase
Bureau of Radiological Health
Division of Public Health Services
Health and Welfare Building
Six Hazen Drive
Concord, NH 03301
(603)271-4674
1-800-852-3345 x4674
New Jersey Tonalee Carlson Key
Division of Environmental Quality
Department of Environmental
Protection
CN415
Trenton, NJ 08625-0145
(609)987-6369
1-800-648-0394 in state
New Mexico William M. Floyd
Radiation Licensing and Registration
Section
New Mexico Environmental
Improvement Division
1190 St Francis Drive
Santa Fe,NM 87503
(505)827-4300
New York William J. Condon
Bureau of Environmental Radiation
Protection
New York State Health Department
Two University Place
Albany, NY 12202
(518)458-6495
1-800-458-1158 in state
North Carolina Dr. Felix Fong
Radiation Protection Division
Department of Environmental Health
and Natural Resources
701 Barbour Drive
Raleigh, NC 27603-2008
(919)571-4141
1-800-662-7301 (recorded info x4196)
North Dakota Alien Jacobson
North Dakota Department of Health
1200 Missouri Avenue, Room 304
P.O. Box 5520
Bismarck, ND 58502-5520
(701)221-5188
Ohio MartieMatmews
Radiological Health Program
Department of Health
1224 Kinnear Road - Suite 120
Columbus, OH 43212
(614)644-2727
1-800-523-4439 in state
n-30 Reprinted from USGS Open-File Report 93-292
-------
Oklahoma
Orepon
Pennsylvania
Puerto Rico
Rhode Island
South Carolina
Gene Smith
Radiation Protection Division
Oklahoma State Department of
Health
P.O. Box 53551
Oklahoma City, OK 73152
(405)271-5221
George Toombs
Department of Human Resources
Health Division
1400 SW 5th Avenue
Portland, OR 97201
(503)731-4014
Michael Pyles
Pennsylvania Department of
Environmental Resources
Bureau of Radiation Protection
P.O. Box 2063
Harrisburg, PA 17120
(717)783-3594
1-800-23-RADON In State
David Saldana
Radiological Health Division
G-P.O. Call Box 70184
Rio Piedras, Puerto Rico 00936
(809)767-3563
Edmund Arcand
Division of Occupational Health and
Radiation
Department of Health
205 Cannon Building
Davis Street
Providence, RI02908
(401)277-2438
Bureau of Radiological Health
Department of Health and
Environmental Control
2600 Bull Street
Columbia, SC 29201
(803)734-4631
1-800-768-0362
South Dakr^ MikePochop
Division of Environment Regulation
1 Department of Water and Natural
Resources
Joe Foss Building, Room 217
523 E. Capitol
Pierre, SD 57501-3181
(605)773-3351
Susie Shimek
Division of Air Pollution Control
Bureau of the Environment
Department of Environment and
Conservation
Customs House, 701 Broadway
Nashville, TN 37219-5403
(615)532-0733
1-800-232-1139 in state
Gary Smith
Bureau of Radiation Control
Texas Department of Health
1100 West 49th Street
Austin, TX 78756-3189
(512)834-6688
John Hultquist
Bureau of Radiation Control
Utah State Department of Health
288 North, 1460 West
P.O. Box 16690
Salt Lake City, UT 841 16-0690
(801)536-4250
Vermont Paul demons
Occupational and Radiological Health
Division
Vermont Department of Health
10 Baldwin Street
Montpelier, VT 05602
(802)828-2886
1-800-640-0601 in state
Virgin Islands Contact the U.S. Environmental
Protection Agency, Region JJ
in New York
(212)264-4110
11-31 Reprinted from USGS Open-File Report 93-292
-------
Virginia Shelly Ottenbrite
Bureau of Radiological Health
Department of Health
109 Governor Street
Richmond, VA 23219
(804)786-5932
1-800-468-0138 in state
Washington KateColeman
Department of Health
Office of Radiation Protection
Airdustrial Building 5, LE-13
Olympia,WA 98504
(206)753-4518
1-800-323-9727 In State
West Virginia BeattieL.DeBprd
Industrial Hygiene Division
West Virginia Department of Health
151 llth Avenue
South Charleston, WV 25303
(304)558-3526
1-800-922-1255 In State
Wisconsin Conrad Weiffenbach
Radiation Protection Section
Division of Health
Department of Health and Social
Services
P.O. Box 309
Madison, WI53701-0309
(608)267-4796
1-800-798-9050 in state
Wyoming Janet Hough
Wyoming Department of Health and
Social Services
Hathway Building, 4th Floor
Cheyenne, WY 82002-0710
(307)777-6015
1-800-458-5847 in state
n-32 Reprinted from USGS Open-File Report 93-292
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STATE GEOLOGICAL SURVEYS
May, 1993
Alabama Ernest A. Mancini
Geological Survey of Alabama
P.O. Box 0
420 Hackbeny Lane
Tuscaloosa, AL 35486-9780
(205)349-2852
Thomas E. Smith
Alaska Division of Geological &
Geophysical Surveys
794 University Ave., Suite 200
Fairbanks, AK 99709-3645
(907)479-7147
Larry D. Fellows
Arizona Geological Survey
845 North Park Ave., Suite 100
Tucson, AZ 85719
(602)882-4795
Norman F. Williams
Arkansas Geological Commission
Vardelle Parham Geology Center
3815 West Roosevelt Rd.
Little Rock, AR 72204
(501)324-9165
California James F. Davis
California Division of Mines &
Geology
801 K Street, MS 12-30
Sacramento, CA 95814-3531
(916)445-1923
Pat Rogers (Acting)
Colorado Geological Survey
1313 Sherman St. Rm 715
Denver, CO 80203
(303)866-2611
Connecticut Richard C. Hyde
Connecticut Geological & Natural
History Survey
165 Capitol Ave., Rm. 553
Hartford, CT 06106
(203)566-3540
Delaware Robert R. Jordan
Delaware Geological Survey
University of Delaware
101 Penny Hall
Newark, DE 19716-7501
(302) 831-2833
Honda Walter Schmidt
Florida Geological Survey
903 W. Tennessee St
Tallahassee, FL 32304-7700
(904)488-4191
William H. McLemore
Georgia Geologic Survey
Rm. 400
19 Martin Luther King Jr. Dr. SW
Atlanta, GA 30334
(404)656-3214
Hawaii Manabu Tagomori
Dept of Land and Natural Resources
Division of Water & Land Mgt
P.O. Box 373
Honolulu, HI 96809
(808)548-7539
EarlH. Bennett
Idaho Geological Survey
University of Idaho
Morrill Hall, Rm. 332
Moscow, ID 83843
(208)885-7991
Illinois Morris W.Leighton
Illinois State Geological Survey
Natural Resources Building
615 East Peabody Dr.
Champaign, XL 61820
(217)333-4747
Indiana
Iowa
Norman C. Hester
Indiana Geological Survey
611 North Walnut Grove
Bloomington, IN 47405
(812)855-9350
Donald L. Koch
Iowa Department of Natural Resources
Geological Survey Bureau
109 Trowbridge Hall
Iowa City, IA 52242-1319
(319)335-1575
Lee C.Gerhard
Kansas Geological Survey
1930 Constant Ave., West Campus
University of Kansas
Lawrence, KS 66047
(913)864-3965
11-33 Reprinted from USGS Open-File Report 93-292
-------
Kentucky Donald C Haney
Kentucky Geological Survey
University of Kentucky
228 Mining & Mineral Resources
Building
Lexington, KY 40506-0107
(606)257-5500
Louisiana William E. Marsalis
Louisiana Geological Survey
P.O. Box 2827
University Station
Baton Rouge, LA 70821-2827
(504)388-5320
Walter A. Anderson
Maine Geological Survey
Department of Conservation
State House, Station 22
Augusta, ME 04333
(207)289-2801
Maryland Emery T. Cleaves
Maryland Geological Survey
2300 St Paul Street
Baltimore, MD 21218-5210
(410)554-5500
Massachusetts Joseph A. Sinnott
Massachusetts Office of
Environmental Affairs
100 Cambridge St, Room 2000
Boston, MA 02202
(617)727-9800
Michigan R. Thomas Segall
Michigan Geological Survey Division
Box 30256
Lansing, MI 48909
(517)334-6923
Minnesota Priscilla C. Grew
Minnesota Geological Survey
2642 University Ave.
SL Paul, MN 55114-1057
(612)627-4780
Mississippi S. Cragin Knox
Mississippi Office of Geology
P.O. Box 20307
Jackson, MS 39289-1307
(601)961-5500
Missouri James H. Williams
Missouri Division of Geology &
Land Survey
111 Fairgrounds Road
P.O. Box 250
Rolla, MO 65401
(314)368-2100
Montana Edward T.Ruppel
Montana Bureau of Mines & Geology
Montana College of Mineral Science
and Technology, Main Hall
Butte.MT 59701
(406)496-4180
Nebraska
Perry B. Wigley
Nebraska Conservation & Survey
Division
113 Nebraska Hall
University of Nebraska
Lincoln, ME 68588-0517
(402)472-2410
Jonathan G. Price
Nevada Bureau of Mines & Geology
Stop 178
University of Nevada-Reno
Reno, NV 89557-0088
(702)784-6691
New Hampshire Eugene L.Boudette
Dept of Environmental Services
117 James Hall
University of New Hampshire
Durham, NH 03824-3589
(603)862-3160
New Jersey Haig F. Kasabach
New Jersey Geological Survey
P.O. Box 427
Trenton, NJ 08625
(609)292-1185
New Mexico Charles E. Cnapin
New Mexico Bureau of Mines &
Mineral Resources
Campus Station
Socorro.NM 87801
(505)835-5420
New York Robert HLFakundiny
New York State Geological Survey
3136 Cultural Education Center
Empire State Plaza
Albany, NY 12230
(518)474-5816
11-34 Reprinted from USGS Open-File Report 93-292
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North Carolina Charles H. Gardner
North Carolina Geological Survey
P.O. Box 27687
Raleigh, NC 27611-7687
(919)733-3833
North Dakota John P. Bluemle
North Dakota Geological Survey
600 East Blvd.
Bismarck, ND 58505-0840
(701)2244109
Ohio Thomas M. Berg
Ohio DepL of Natural Resources
Division of Geological Survey
4383 Fountain Square Drive
Columbus, OH 43224-1362
(614)265-6576
Oklahoma Charles J. Mankin
Oklahoma Geological Survey
Room N-131, Energy Center
lOOE.Boyd
Norman, OK 73019-0628
(405)325-3031
Donald A. Hull
Dept of Geology & Mineral IndusL
Suite 965
800 NE Oregon SL #28
Portland, OR 97232-2162
(503)731-4600
Pennsylvania Donald M. Hoskins
DepL of Environmental Resources
Bureau of Topographic & Geologic
Survey
P.O. Box 2357
Harrisburg, PA 17105-2357
(717)787-2169
Puerto Rico Ram6n M. Alonso
Puerto Rico Geological Survey
Division
Box 5887
Puerto de Tierra Station
San Juan, PJt 00906
(809)722-2526
Rhode Island J. Allan Cain
Department of Geology
University of Rhode Island
315 Green Hall
Kingston, RI 02881
(401)792-2265
South Carolina Alan-Jon W. Zupan (Acting)
South Carolina Geological Survey
5 Geology Road
Columbia, SC 29210-9998
(803)7'"'-9440
South Dakota CM. Christensen (Acting)
South Dakota Geological Survey
Science Center
University of South Dakota
Vermfllion, SD 57069-2390
(605)677-5227
Tennessee Ed ward T.Luther
Tennessee Division of Geology
13thFloor,L&C Tower
401 Church Street
Nashville, TN 37243-0445
(615)532-1500
William L. Fisher
Texas Bureau of Economic Geology
University of Texas
University Station, Box X
Austin, TX 78713-7508
(512)471-7721
Utah M Lee Allison
Utah Geological & Mineral Survey
2363 S. Foothill Dr.
Salt Lake City, UT 84109-1491
(801)467-7970
Vermont Diane L. Conrad
Vermont Division of Geology and
Mineral Resources
103 South Main St
Waterbury.VT 05671
(802)244-5164
Virginia Stanley S. Johnson
Virginia Division of Mineral
Resources
P.O. Box 3667
Chariottesville, VA 22903
(804)293-5121
Washington Raymond Lasmanis
Washington Division of Geology &
Earth Resources
Department of Natural Resources
P.O. Box 47007
Olympia, Washington 98504-7007
(206)902-1450
n-35 Reprinted from USGS Open-File Report 93-292
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West Virginia Larry D.Woodfcik
West Virginia Geological and
Economic Survey
Mont Chateau Research Center
P.O. Box 879
Morgantown.WV 26507-0879
(304)594-2331
Wisconsin James Robertson
Wisconsin Geological & Natural
History Survey
3817 Mineral Point Road
Madison, WI 53705-5100
(608)263-7384
Wyoming Gary B. Glass
Geological Survey of Wyoming
University of Wyoming
Box 3008, University Station
Laramie, WY 82071-3008
(307)766-2286
H-36 Reprinted from USGS Open-Rle Report 93-292
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EPA REGION 3 GEOLOGIC RADON POTENTIAL SUMMARY
by
Linda CS. Gundersen, James K. Otton, and Sandra L. Szarzi
US. Geological Survey
EPA Region 3 includes the states of Delaware, Maryland, Pennsylvania, Virginia, and
West Virginia.. For each state, geologic radon potential areas were delineated and ranked on the
basis of geologic, soil, housing construction, and other factors. Areas in which the average
screening indoor radon level of all homes within the area is estimated to be greater than 4 pCi/L
were ranked high. Areas in which the average screening indoor radon level of all homes within the
area is estimated to be between 2 and 4 pCi/L were ranked moderate/variable, and areas in which
the average screening indoor radon level of all homes within the area is estimated to be less than
2 pQ/L were ranked low. Information on the data used and on the radon potential ranking scheme
is given in the introduction to this volume. More detailed information on the geology and radon
potential of each state in Region 3 is given in the individual state chapters. The individual chapters
describing the geology and radon potential of the states in EPA Region 3, though much more
detailed than this summary, still are generalized assessments and there is no substitute for having a
home tested. Within any radon potential area homes with indoor radon levels both above and
below the predicted average will likely be found.
Figure 1 shows a generalized map of the major physiographic/geologic provinces in EPA
Region 3. The summary of radon potential in Region 3 that follows refers to these provinces.
Figure 2 shows average screening indoor radon levels by county. The data for Maryland,
Pennsylvania, Virginia, and West Virginia are from the State/EPA Residential Radon Survey. Data
for Delaware were compiled by the Delaware Department of Health and Social Services. Figure 3
shows the geologic radon potential areas in Region 3, combined and summarized from the
individual state chapters in this booklet
DELAWARE
Piedmont
The Piedmont in Delaware has been ranked moderate in geologic radon potential. Average
measured indoor radon levels in the Piedmont vary from low (<2 pCi/L) to moderate (2-4 pCi/L).
Individual readings within the Piedmont can be locally very high (> 20 pCi/L). This is not
unexpected when a regional-scale look at the Atlantic coastal states shows that the Piedmont is
consistently an area of moderate to high radon potential. Much of the western Piedmont in
Delaware is underlain by the Wissahickon Formation, which consists predominantly of schist
This formation has moderate to locally high geologic radon potential. Equivalent schists in the
Piedmont of Maryland can have uranium concentrations of 3-5 ppm, especially where faulted.
The Wilmington Complex and James Run Formation, in the central and eastern portions of the
Delaware Piedmont are variable in radon potential. In these units, the felsic gneiss and schist may
contribute to elevated radon levels, whereas mafic rocks such as amphibolite and gabbro, and
relatively quartz-poor granitic rocks such as charnockite and diorite are probably lower in radon
potential. The average indoor radon is distinctly lower in parts of the Wilmington Complex than in
surrounding areas, particularly in areas underlain by the Bringhurst Gabbro and the Arden pluton.
The permeability of soils in the Piedmont is variable and dependent on the composition of the rocks
from which the soils are derived. Most soils are moderately permeable, with local areas of slow to
m-1 Reprinted from USGS Open-FUe Report 93-292-C
-------
-------
100
miles
Low Plateau, Western Portion: 10-oLiated IS, P£ uSSS^PP^1115? Mountains; 9-Glaciated
-------
100 Miles
Indoor Radon Screening
Measurements: Average (pCi/L)
61 GZ3 0.0 to 1.9
81 YSSSA 2.0 to 4.0
57 E2J22 4.1 to 10.0
20 Bi 10.1 to 32.6
65 ' ' Missing Data
or < 5 measurements
Figure 2. Screening indoor radon averages for counties with 5 or more measurements in EPA
Region 3. Data for Maryland, Pennsylvania, Virginia, and West Virginia are from the State/EPA
Residential Radon Survey. Data for Delaware were compiled by the Delaware Department of
Health and Social Services. Histograms in map legend show the number of counties in each
category.
-------
GEOLOGIC
RADON POTENTIAL
MODERATE/VARIABLE
I HIGH
100
Figure 3. Geologic radon potential of EPA Region 3. For more detail, refer to individual state
radon potential chapters.
-------
-------
rapid permeability. Limited aereal radioactivity data for the Delaware Piedmont indicates that
equivalent uranium is generally moderate (1.5-2.5 ppm).
CoastalPlcdn
Studies of radon and uranium in Coastal Plain sediments in New Jersey and Maryland
suggest that glauconitic marine sediments equivalent to those in the northern portion of the
Delaware Coastal Plain can cause elevated levels of indoor radon. Central New Castle County is
underlain by glaucomtic marine sediments of Cretaceous and Tertiary age that have moderate to
locally high radon potential. Aerial radiometric data indicate that moderate concentrations of
uranium occur in rocks and soils associated with the Piedmont and parts of the Coastal Plain of
northern Delaware. Chemical analyses of Cretaceous and Tertiary glauconitic marine sediments
and fluvial sediments of the Columbia Formation performed by the Delaware geological survey
indicate variable but generally moderate concentrations of uranium, averaging 1.89 ppm or greater
The permeability of soils in these areas is variable but generally moderate to high, allowing radon '
gas to move readily through the soil. Data for New Castle County from the State indoor radon
survey shows that areas underlain by the Cretaceous fluvial sediments (not glauconitic) have lower
average indoor radon levels than the glauconitic parts of the upper Cretaceous and lower Tertiary
sequence to the south. Kent County and all of Sussex County are underlain by quartz-dominated
sands, silts, gravels, and clays with low radon potential. These sediments are low in radioactivity
and generally have a low percentage of homes with indoor radon levels greater than 4 pCS/L.
MARYLAND
CoastalPlain
The Western Shore of Maryland has been ranked moderate to locally high in radon potential
and the Eastern Shore has been ranked low in radon potential The Coastal Plain Province is
underlain by relatively unconsolidated fluvial and marine sediments that are variably phosphatic
and glauconitic on the Western Shore, and dominated by quartz in the Eastern Shore
Radioactivity in the Coastal Plain is moderate over parts of the Western Shore sediments
particularly in the Upper Cretaceous and Tertiary sediments of Prince George's, Anne Arundel
and northern Calvert counties. Moderate radioactivity also appears to be associated with the
Cretaceous and Tertiary sediments of the Eastern Shore where these sediments are exposed in
major drainages in Kent, Queen Anne's, and Talbot counties. Soil-gas radon studies in Prince
George s County indicate that soils formed from the locally phosphatic, carbonaceous or
glauconitic sediments of the Calvert, Aquia, and Nanjemoy Formations can produce significantly
high radon (average soil radon > 1500 pCi/L). The Cretaceous Potomac Group had more
moderate levels of soil radon, averaging 800-900 pCi/L, and the Tertiary-Cretaceous Brightseat
Formation and Monmouth Group had average soil radon of 1300 pCi/L. Soil permeability on the
Western Shore vanes from low to moderate with some high permeability in sandier soils Well-
developed clayey B horizons with low permeability are common. Indoor radon levels measured in
the State/EPA Residential Radon Survey are variable among the counties of the Western Shore but
are generally low to moderate. Moderate to high average indoor radon is found in most of the
Western Shore counties.
For this assessment we have ranked part of the Western Shore as high in radon potential
including Calvert County, southern Anne Arundel County, and eastern Prince George's County'
This area has the highest radioactivity, high indoor radon, and significant exposure of Tertiary rock
ffl-5 Reprinted from USGS Open-File Report 93-292-C
-------
units. The part of the Western Shore ranked moderate consists of Quaternary sediments with low
radon potential, Cretaceous sediments with moderate radon potential, and lesser amounts of
Tertiary sediments with high radon potential. The Quaternary sediments of the Eastern Shore have
low radioactivity associated with them and are generally quartzose and thus low in uranium.
Heavy-mineral concentrations within these sediments may be very local sources of uranium.
Indoor radon appears to be generally low on the Eastern Shore with only a few measurements over
4 pCS/L reported.
Piedmont •
Gneisses and schists in the eastern Piedmont, phyllites in the western Piedmont, and
Paleozoic metasedimentary rocks of the Frederick Valley are ranked high in radon potential.
Sedimentary and igneous roaks of the Mesozoic basins have been ranked moderate in radon
potential. Radioactivity r ins Piedmont is generally moderate to high. Indoor radon is moderate
to high in the eastern Piedmont and nearly uniformly high in the western Piedmont Permeability
is low to moderate in soils developed on the mica schists and gneisses of the eastern Piedmont,
Paleozoic sedimentary rocks of the Frederick Valley, and igneous and sedimentary rocks of the
Mesozoic Basins. Permeability is moderate to high in the soils developed on the phyllites of the
western Piedmont The Maryland Geological Survey has compared the geology of Maryland with
the Maryland indoor radon data. They report that most of the Piedmont rocks, with the exception
of ultramafic rocks, can contribute to indoor radon readings exceeding 4 pQ/L. Their data indicate
that the phyllites of the western Piedmont have much higher radon potential than the schists in the
east Ninety-five percent of the homes built on phyllites of the Gillis Formation had indoor radon
measurements greater than 4 pCi/L, and 47 percent of the measurements were greater than 20
pCi/L. In comparison, 80 percent of the homes built on the schists and gneiss of the Loch Raven
and Delia Formations had indoor radon readings greater than 4 pCi/L, but only 9 percent were
greater than 20 pQ/L.
Studies of the phyllites in Frederick County show high average soil-gas radon (>1000
pQ/L) when compared to other rock types in the county. Limestone and shale soils of the
Frederick Valley and some of the Triassic sedimentary rocks may be significant sources of radon
(500-2000 pCi/L in soil gas). Because of the highly variable nature of the Triassic sediments and
the amount of area that the rocks cover with respect to the county boundaries, it is difficult to say
with confidence whether the high indoor radon in Montgomery, Frederick, and Carroll counties is
partly attributable to the Triassic sediments. Li Montgomery County, high uranium concentrations
in fluvial crossbeds of the upper Manassas Sandstone containing gray carbonaceous clay intraclasts
and drapes have been documented. Similar lithologic associations are common in the upper New
Oxford Formation. Black shales and gray sandstone of the Heidlersburg Member are similar to
uranium-bearing strata in the Culpeper basin in Virginia and may be a source of radon. Black
shales in the overlying Gettysburg Formation may also be locally uranium rich. The lower New
Oxford Formation, the lower Manassas Sandstone, the lower Gettysburg Formation, and the Balls
Bluff Siltstone in Maryland are not likely to have concentrations of uranium except where altered
by diabase intrusives and/or faulted. The diabase bodies are low in radon potential.
Appalachian Mountains
The Appalachian Province is divided into the Blue Ridge, Great Valley, Valley and Ridge,
and Allegheny Plateau. Each of these areas is underlain by a distinct suite of rocks with a
particular geologic radon potential. The Blue Ridge is ranked low in radon potential but may be
m-6 Reprinted from USGS Open-File Report 93-292-C
-------
locally moderate to high. The Catoctin volcanic rocks that underlie a significant portion of the Blue
Ridge have low radioactivity, yield low soil radon and have low soil permeability. The quartzite
and conglomerates overlying the Catoctin also have low radioactivity and low soil-gas radon.
Further, the Pennsylvania Topographic and Geologic Survey calculated the median uranium
content of 80 samples of Catoctin metabasalt and metadiabase to be less than 0.5 ppm. The
Harpers Formation phyllite bordering the Catoctin volcanic rocks yields high soil-gas radon
(>1000 pO/L), has greater surface radioactivity than the surrounding rocks and is a potential
source of radon. The Precambrian gneiss that crops out in the Middletown Valley of the southern
Blue Ridge appears to have moderate radioactivity associated with it and yielded some high radon
in soil gas. It is difficult, given the constraints of the indoor radon data, to associate the high
average indoor radon in the part of Frederick County underlain by parts of this province with the
actual rocks. The Blue Ridge is provisionally ranked low in geologic radon potential, but this
cannot be verified with the presently existing indoor radon data.
Carbonates and black shales in the Great Valley in Maryland have been ranked high in
radon potential. Radioactivity is moderate to high over the Great Valley in Washington County.
Washington County has more than 100 indoor radon measurements, has an average indoor radon
concentration of 8.1 pCi/L in the State/EPA Survey, with over half of the readings greater than
4 pCi/L. To the north in Pennsylvania, carbonate rocks of the Great Valley and Appalachian
Mountain section have been the focus of several studies and the carbonate rocks in these areas
produce soils with high uranium and radium contents that generate high radon concentrations. In
general, indoor radon in these areas is higher than 4 pCi/L. Studies in the carbonates of the Great
Valley in West Virginia suggest that the deepest, most mature soils have the highest radium and
radon concentrations and generate moderate to high indoor radon. High radon in soils and high
indoor radon in homes over the black shales of the Martinsburg Formation of the Great Valley
were also measured in West Virginia.
The Silurian and Devonian rocks of the Valley and Ridge have been ranked moderate to
locally high in geologic radon potential. Indoor radon measurements are generally moderate to
high in Allegany County. Soil permeability is variable but is generally moderate. Radioactivity in
this part of the Valley and Ridge is moderate to locally high. The Tonoloway, Keyser, and Wills
Creek Formations, and Clinton and Hamilton Groups have high equivalent uranium associated
with them and the shales, limestone soils, and hematitic sands are possible sources of the high
readings over these units.
The Devonian through Permian rocks of the Allegheny Plateau are ranked moderate in
geologic radon potential. Indoor radon measurements are generally moderate to high.
Radioactivity in the Allegheny Plateau is low to moderate with locally high equivalent uranium
associated with the Pocono Group and Mauch Chunk Formation. Soil permeability is variable but
generally moderate.
PENNSYLVANIA
New England Province
The New England Province is ranked high in geologic radon potential. A number of
studies on the correlation of indoor radon with geology in Pennsylvania have been done. The
Reading Prong area in the New England Province is the most notable example because of the
national publicity surrounding a particularly severe case of indoor radon. These studies found that
shear zones within the Reading Prong rocks enhanced the radon potential of the rocks and created
ffi-7 Reprinted from USGS Open-FUe Report 93-292-C
-------
«
local occurrences of very high uranium and indoor radon. Several of the rock types in the Reading
Prong were found to be highly uraniferous in general and they are the source for high radon levels
throughout much of the province. :
Piedmont
The Piedmont is underlain by metamorphic, igneous, and sedimentary rocks of
Prccambrian to Mesozoic age that have generally moderate to high radon potential. Rock types in
the metamorphic crystalline portion of the Piedmont mat have naturally elevated uranium
concentrations include granitic gneiss, biotite schist, and gray phyllite. Rocks that are known
sources of radon and have high indoor radon associated with them include phyllites and schists,
such as the Wissahickon Formation and Peters Creek Schist, shear zones in these rocks, and the
faults surrounding mafic bodies within these rocks.
Studies in the Newark Basin of New Jersey indicate that the black shales of the Lockatong
and Passaic Formations and fluvial sandstones of the Stockton Formation are a significant source
of radon in indoor air and in water. Where these rock units occur in Pennsylvania, they may be the
source of high indoor radon as well. Black shales of the Heidlersburg Member and fluvial
sandstones of the New Oxford Formation may also be sources of locally moderate to high indoor
radon in the Gettysburg Basin. Diabase sheets and dikes within the basins have low eU. The
Mesozoic basins as a whole, however, are variable in their geologic radon potential. The Narrow
Neck area is distinctly low in radioactivity and Montgomery County, which is underlain almost
entirely by Mesozoic basin rocks, has an indoor radon average less than 4 pCS/L. Other counties
underlain partly by the Mesozoic basin rocks, however, have average indoor radon greater than
4 pCi/L. The Newark basin is high in radon potential whereas the Gettysburg basin is low to
locally moderate. For the purposes of this report the basins have been subdivided along the
Lancaster-Berks county boundary. The Newark basin comprises the Mesozoic rocks east of this
county line.
Blue Ridge
The Blue Ridge Province is underlain by metasedimentary and metavolcanic rocks and is
generally an area of low radon potential. A distinct low area of radioactivity is associated with the
province on the map, although phyllite of the Harpers Formation may be uraniferous. Soils
generally have variable permeability. The metavolcanic rocks in mis province have very low
uranium concentrations. It is difficult, given the constraints of the indoor radon data, to associate
the high average indoor radon in counties underlain by parts of this province with specific rock
units. When the indoor radon data are examined at the zip code level, it appears that most of the
high indoor radon is attributable to the Valley and Ridge soils and rocks. The conclusion is that the
Blue Ridge is provisionally ranked low in geologic radon potential although this cannot be verified
with the presently available indoor radon data.
Ridge and Valley and Appalachian Plateaus
Carbonate rocks of the Great Valley and Appalachian Mountain section have been the focus
of several studies and the carbonates in these areas produce soils with high uranium and radium
contents and soil radon concentrations. In general, indoor radon in these areas is higher than
4 pCi/L and the geologic radon potential of the area is high, especially in the Great Valley where
indoor radon is distinctly higher on the average than in surrounding areas. Soils developed on
m-8 Reprinted from USGS Open-File Report 93-292-C
-------
limestone and dolomite rock at the surface in the Great Valley, Appalachian Mountains, and
Piedmont are probably sources of high indoor radon.
The clastic rocks of the Ridge and Valley and Appalachian Plateaus province, particularly
the Qrdovician through Pennsylvanian-age black to gray shales and fluvial sandstones, have been
extensively cited in the literature for then- uranium content as well as their general uranium
potential. It appears from the uranium and radioactivity data and comparison with the indoor radon
data that the black shales of the Qrdovician Martinsburg Formation, the lower Devonian black
shales, Pennsylvanian black shales of the Allegheny Group, Conemaugh Group, and Monogahela
Group, and the fluvial sandstones of the Devonian Catskill and Mississippian Mauch Chunk
Formation may be the source of most moderate to high indoor radon levels in the Appalachian
Plateau and parts of the Appalachian Mountains section.
Only a few areas in these provinces appear to have geologically low to moderate radon
potential. The Greene Formation in Greene County appears to correlate with distinctly low
radioactivity. The indoor radon for Greene County averages less than 4 pCi/L for the few
measurements available in the State/EPA survey.
Somerset and Cambria Counties in the Allegheny Mountain section have indoor radon
averages less than 4 pCi/L, and it appears that low radioactivity and slow permeability of soils may
be factors in the moderate geologic radon potential of this area. These two counties and most of
the Allegheny Mountain section are underlain by Pennsylvanian-age sedimentary rocks. The
radioactivity map shows low to moderate radioactivity for the Pennsylvanian-age rocks in the
Allegheny Mountain section and much higher radioactivity in the Pittsburgh Low Plateau section.
Most of the reported uranium occurrences in these rocks appear to be restricted to the north and
west of the Allegheny Mountain section. Approximately half of the soils developed on these
sediments have slow permeability and seasonally high water tables.
Coastal Plain
Philadelphia and Delaware Counties, in the southeastern corner of Pennsylvania, have
average indoor radon less than 4 pCi/L and have low radioactivity. Part of Delaware County and
most of Philadelphia County are underlain by Coastal Plain sediments with low uranium
concentrations. Soils developed on these sediments are variable, but a significant portion are
clayey with slow permeability.
Glaciated Areas cf Pennsylvania
Radiometric lows and relatively lower indoor radon levels appear to be associated with the
glaciated areas of the State, particularly the eastern portion of the Glaciated Low Plateau and
Pocono Plateau in Wayne, Pike, Monroe, and Lackawanna Counties. Glacial deposits are
problematic to assess for radon. In some areas of the glaciated portion of the United States, glacial
deposits enhance radon potential, especially where the deposits have high permeability and are
derived from uraniferous source rocks. In other portions of the glaciated United States, glacial
deposits blanket more uraniferous rock or have low permeability and corresponding low radon
potential. The northeastern corner of Pennsylvania is covered by the Olean Till, made up of 80-90
percent sandstone and siltstone clasts with minor shale, conglomerate, limestone, and crystalline
clasts. A large proportion of the soils developed on this till have seasonally high water tables and
poor drainage, but some parts of the till soils are stony and have good drainage and high
permeability. Low to moderate indoor radon levels and radioactivity in this area may be due to the
seasonally saturated ground and to the tills being made up predominantly of sandstones and
ffl-9 Reprinted from USGS Open-File Report 93-292-C
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siltstones with low uranium contents. A similar situation exists in the northwestern part of the
State, which is covered by a wide variety of tills, predominantly the Kent Till, which contains
mostly sandstone, siltstone, and shale clasts. Many of the soils in this area also have low
permeabilities and seasonally high water tables. Where the tills are thinner, the western portion of
the Glaciated Low Plateau has higher indoor radon and high radioactivity.
VIRGINIA
CoastalPlcun
The Coastal Plain of Virginia is ranked low in geologic radon potential. Indoor radon is
generally low; however, moderate to high indoor radon can occur locally and may be associated
with phosphatic, glauconitic, or heavy mineral-bearing sediments. Equivalent uranium over the
Tertiary units of the Coastal Plain is generally moderate. Soils developed on the Cretaceous and
Tertiary units are slowly to moderately permeable. Studies of uranium and radon in soils indicate
that the Yorktown Formation could be a source for elevated levels of indoor radon. The
Quaternary sediments generally have low eU associated with them. Heavy mineral deposits of
monaate found locally within the Quaternary sediments of the Coastal Plain may have the potential
to generate locally moderate to high indoor radon.
Piedmont
The Goochland terrane and Inner Piedmont have been ranked high in radon potential.
Rocks of the Goochland terrane and Inner Piedmont have numerous well-documented uranium and
radon occurrences associated with granites; pegmatites; granitic gneiss; monazite-bearing
mctascdimentary schist and gneiss; graphitic and carbonaceous slate, phyllite, and schist; and shear
zones. Indoor radon is generally moderate but significant very high radon levels occur in several
areas. Equivalent uranium over the Goochland terrane and Inner Piedmont is predominantly high
to moderate with areas of high eU more numerous in the southern part Permeability of soils
developed over the granitic igneous and metamorphic rocks of the Piedmont is generally moderate.
Within the Goochland terrane and Inner Piedmont, local areas of low to moderate radon potential
will probably be found over mafic rocks (such as gabbro and amphibolite), quartzite, and some
quartzitic schists. Mafic rocks have generally low uranium concentrations and slow to moderate
permeability in the soils they form.
The Carolina terrane is variable in radon potential but is generally moderate. Metavolcanic
rocks have low eU but the granites and granitic gneisses have moderate to locally high eU. Soils
developed over the volcanic rocks are slowly to moderately permeable. Granite and gneiss soils
have moderate permeability.
The Mesozoic basins have moderate to locally high radon potential. It is not possible to make
any general associations between county indoor radon averages and the Mesozoic basins as a
whole because of the limited extent of many the basins. However, sandstones and siltstones of the
Culpeper basin, which have been lightly metamorphosed and altered by diabase intrusion, are
mineralized with uranium and cause documented moderate to high indoor radon levels in northern
Virginia. Lacustrine black shales and some of the coarse-grained gray sandstones also have
significant uranium mineralization, often associated with green clay clasts and copper. Equivalent
uranium over the Mesozoic basins varies among the basins. The Danville basin has very high eU
associated with it whereas the other basins have generally moderate eU. This radioactivity may be
related to extensive uranium mineralization along the Chatham fault on the west side of the Danville
m-10 Reprinted from USGS Open-File Report 93-292-C
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basin. Localized higheU also occurs over the western border fault of the Culpeper basin. Soils
are generally slowly to moderately permeable over the sedimentary and intrusive rocks of the
basins.
Valley and Ridge
The Valley and Ridge has been ranked high in geologic radon potential but some areas have
locally low to moderate radon potential. The Valley and Ridge is underlain by Cambrian dolomite,
limestone, shale, and sandstone; SUurian-Ordovician limestone, dolomite, shale, and sandstone;
and Mississippian-Devonian sandstone, shale, limestone, gypsum, and coal. Soils derived from
carbonate rocks and black shales, and black shale bedrock may be sources of the moderate to high
levels of indoor radon in this province. Equivalent uranium over the Valley and Ridge is generally
low to moderate with isolated areas of high radioactivity. Soils are moderately to highly
permeable. Studies of radon in soil gas and indoor radon over the carbonates and shales of the
Great Valley in West Virginia and Pennsylvania indicate that the rocks and soils of this province
constitute a significant source of indoor radon. Sandstones and red siltstones and shales are
probably low to moderate in radon potential. Some local uranium accumulations are contained in
these rocks.
Appalachian Plateaus
The Appalachian Plateaus Province has been ranked moderate in geologic radon potential.
The plateaus are underlain by Pennsylvanian-age sandstone, shale, and coal. Black shales,
especially those associated with coal seams, are generally elevated in uranium and may be the
source for moderate to high radon levels. The coals themselves may also be locally elevated in
uranium. The sandstones are generally low to moderate in radon potential but have higher soil
permeability than the black shales. Equivalent uranium of the province is low to moderate and
indoor radon is variable from low to high, but indoor radon data are limited in number.
WEST VIRGINIA
Allegheny Plateau
The Central Allegheny Plateau Province has moderate geologic radon potential overall, due
to persistently moderate eU values and the occurrence of steep, well-drained soils. However,
Brooke and Hancock counties, in the northernmost part of this province, have average indoor
radon levels exceeding 4 pCi/L. This appears to be related to underlying Conemaugh and
Monongahela Group sedimentary rocks which have elevated eU values in this area and in adjacent
areas of western Pennsylvania.
The Cumberland Plateau and Mountains Province has low radon potential. The eU values
for the province are low except in areas of heavy coal mining, where exposed shale-rich mine
waste tends to increase values. Indoor radon levels average less than 2 pCi/L in most counties.
The Eastern Allegheny Plateau and Mountains Province has moderate radon potential
overall. Locally high indoor radon levels are likely in homes on dark gray shales of Devonian age
and colluvium derived from them in Randolph County. The southern part of this province has
somewhat lower eU values and indoor radon averages.
m-11 Reprinted from USGS Open-File Report 93-292-C
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Ridge and Valley Province
The southern part of the Appalachian Ridge and Valley Province in West Virginia has
moderate radon potential overall. The eU signature for this province is elevated (> 2.5 ppm elJ).
Locally high radon potential occurs in areas of deep residual soils developed on limestones of the
Mississippian Greenbrier Group, especially in central Greenbrier County, where eU values are
high. Elevated levels of radon may be expected in soils developed on dark shales in this province
or in colluvium derived from them.
The northern part of the Appalachian Ridge and Valley Province in West Virginia has high
geologic radon potential. The soils in this area have an elevated eU signature. Soils developed on
the Martinsburg Formation and on limestones and dolomites throughout the Province contain
elevated levels of radon and a very high percentage of homes have indoor radon levels exceeding
4 pQ/L in this province. Karst topography and associated locally high permeability in soils
increases the radon potential. Structures sited on uraniferous black shales may have very high
indoor radon levels. Steep, well-drained soils developed on phyllites and quartzites of the Harpers
Formation in Jefferson County also produce high average indoor radon levels.
ffl-12 Reprinted from USGS Open-File Report 93-292-C
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PRELIMINARY GEOLOGIC RADON POTENTIAL ASSESSMENT OF PENNSYLVANIA
by
Linda C.S. Gundersen and Joseph P. Smoot
US. Geological Survey
INTRODUCTION
This is a generalized assessment of geologic radon potential of rocks, soils, and surficial
deposits of Pennsylvania. The scale of this assessment is such that it is inappropriate for use in
identifying the radon potential of small areas such as neighborhoods, individual building sites, or
housing tracts. Any localized assessment of radon potential must be supplemented with additional
data and information from the locality. Within any area of a given radon potential ranking, there
are likely to be areas with higher or lower radon levels than characterized for the area as a whole.
Indoor radon levels, both high and low, can be quite localized, and there is no substitute for testing
individual homes. Elevated levels of indoor radon have been found in every State, and EPA
recommends that all homes be tested. For more information on radon, the reader is urged to
consult the local or State radon program or EPA regional office. More detailed information on state
or local geology may be obtained from the state geological survey. Addresses and phone numbers
for these agencies are listed in chapter 1 of this booklet
PHYSIOGRAPHIC AND GEOGRAPHIC SETTING
The physiography of Pennsylvania (fig. 1) is in part a reflection of the underlying bedrock
geology (fig. 2). Pennsylvania is divided into seven major physiographic provinces: the New
England, the Piedmont, the Blue Ridge, the Ridge and Valley, the Appalachian Plateaus, the
Central Lowland, and the Atlantic Coastal Plain. Several of these provinces are subdivided into
smaller regions (fig. 1) which will be referred to throughout this report.
The New England Province is underlain by metamorphic rocks of Precambrian age and is
an area of steep rolling hills and valleys. Elevation varies from 90 to over 300 meters above sea
level and local relief is several hundred meters. The Piedmont Province is subdivided into the
Piedmont Upland, Piedmont Lowland, and Gettysburg-Newark Lowland sections. The Piedmont
Upland is underlain by metamorphic, igneous, and sedimentary rocks of Precambrian and
Paleozoic age. Low rolling hills with elevation varying between 60 and 150 m above sea level
characterize the southern part of the region, whereas in the northern part, the topography is similar
to that of the New England Province with elevations over 250 m. The Piedmont Lowland is
underlain by carbonate rocks of Paleozoic age with relatively low relief varying between 120 and
150 m in elevation. The Gettysburg-Newark Lowland consists of northeast-trending low hills and
valleys underlain by Triassic siltstone, shale, and sandstone. Elevation is between 60 and 150 m
above sea level. Triassic conglomerates and Jurassic diabase sheets form locally steeper
topography, with elevations over 300 m.
The Blue Ridge Province is an area of steep mountains underlain by metamorphic rocks of
Precambrian and Cambrian age and having elevations from 200 to 600 m. The Ridge and Valley
Province consists of parallel ridges and valleys with an arcuate north-northeast trend. Ridges are
underlain by sandstone and conglomerate, whereas valleys are underlain by shales and limestones.
The Ridge and Valley is subdivided into the Great Valley and Appalachian Mountain sections. The
Great Valley is a broad area of low relief underlain by carbonate rocks, sandstones, and shales.
Carbonate areas have elevations generally between 120 and 150 m above sea level, whereas areas
IV-l Reprinted from USGSOpen-FUe Report 93-292-C
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Explanation, Pennsylvania General Geologic Map
Precambrian
^thSma11 """ of hoiriblende
gn*hitic gneiss,
Blue Ridge province - metarhyolite, metabasalt and greenstone
^J^ySJ^1"^ \tomblente and ppoxenefelsic gneiss with small areas of mafic hornblende
gneiss of sedunentoy ongminnoimem Chester County and intennixed granodiorite, qaaitemonzoni
gabbroic, and graphitic gneisses and pods of anorthosite in southern CheSr and 1 DelkwareSS
,, x „ Lower Paleozoic
Metasedimentary and meta-igneous locks includes:
ic gneiss, mafic gneiss, and serpentinite.
_. , . Cambrian
Piedmont province - Quartzite and phyllite including the Chickies, Haipeis, and Antietem
imanons, overlain bv dolomite and limpQtnnp with minm- oh«io «t»i..^:.._ *«.-«• ± »£r^
_.
shale
Ordovician
ite of the Conestoga, Stonehenge,
Overi^^sh^^
us sandstone and quartz sandstone of the CocalicoFonnation.
Ontelaunee and
-Limestone and dolomite of the Stonehenee Rickenbach. Enler
"* MeyeistownFonnations overiain^^e SS an^minor
hmestone of the Hamburg sequence and theMartinsbuigFoimatioa yw««. «mu mmor
in J2? ter"GJeatValley section - Limestone and dolomite of the Stonehenge, Rockdale Run,
dolomite, aigUlaceous limestone and minor shale of me
, Hatter, Snyder, Benner, and
, , , ,
Formations overiain by gray shale and siltstone of me Reedsvffle Fonnation and sandstone dSe
conglomerate and shale of the Bald Eagle and JuniataFormations. wnasrane, aiisrone,
Silurian
Eastern Appalachian Mountain section north of Great Valley -
ShawannkFonnation overlainby red siltstone, shale, and
um- Qrthoquartzite and conglomerate of the Tuscarora
f^i1^
""d dolomite of the Mifflintown, Bloomsburg, and Wills
„ . Devonian
Eastern Appalachian Mountain section - Limestone, argillaceous limestone <
aid sihceous sandstone of the Coeymans and New Scotland Formations, Minisii
uwen Jrfiale, Shnver Chert, Ridgeley, Esopus, and Schoharie Formations, and Pahnerton Sandstone
and Buttermilk Falls Limestone overlain by black carbonaceous shales and gray shalesriltetonesmd
fine sandstones of fte MarceUus Mahantango, and Trimmers Rock FormatiSS Sy S^
intermittentiy gray sandstone, siltstone and shale of the Catskill Formation.
West-Central Appalachian Mountain section - limestone and minor shale of the Tonolowav and
Keyser Formations overlain by gray siltstone, argillaceous limestone, shale, and quartz sarXne of the
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Oldport and Onondaga Formations, overlain by carbonaceous shales, siltstones, and sandstones of the
Marcellus, Mahantango, Trimmers Rock, Brallier, Hanell, Scherr, and Foreknobs Fonnations and
finally red and intermittently gray sandstone, siltstone and shale of me Catskill Formation.
Eastern Appalachian Plateaus province - Gray sandstone, siltstone, and mudstone of the Lock
Haven Formation overlain by red and intermittently gray sandstone, siltstone and shale of the Catskill
Formation.
Western Appalachian Plateaus province- Gray shale, siltstone, and sandstone of the upper
Northeast Shale, Girard Shale, Chadakoin and Venango Formations.
Mississippian
Eastern Appalachian Mountain section - Buff sandstone, siltstone, and conglomerate of the Spechty
Kopf and Pocono Formations overlain by red siltstone, sandstone, and shale with minor gray sandstone
of the Mauch Chunk Formation.
Western Appalachian Mountain section - Buff sandstone, siltstone, conglomerate, and minor
carbonaceous shale of the Rockwell and Pocono Formations overlain by red siltstone, sandstone, shale,
and minor gray sandstone of the Mauch Chunk Formation.
Northeastern Appalachian Plateaus province - Greenish -gray fine-grained sandstone with minor
red shale of the Huntley Mountain Formation overlain by buff sandstone and conglomerate of the
Burgoon Sandstone, overlain by red siltstone, sandstone, shale, and minor gray sandstone of the
Mauch Chunk Formation.
Allegheny Mountain section - Buff argillaceous sandstone and green shale of the Rockwell and
Oswayo Formations overlain by buff sandstone and conglomerate of the Burgoon Sandstone, men by
red siltstone, sandstone, shale and minor gray sandstone of the Mauch Chunk Formation.
Northwestern Appalachian Plateaus province - Gray siltstone, shale, and sandstone of theRiceville
Formation, Berea and Cony Sandstones, Cuyahoga Group, and Shenango Formation.
Pennsylvanian
Appalachian Mountain section - Gray conglomerate, sandstone, siltstone, and shale with anthracite
coal beds of the Pottsvflle Group and Llewellyn Formation.
Appalachian Plateaus province - Gray sandstone and conglomerate with minor shale and coal beds
of the Pottsville Group overlain by cyclic gray sandstone, shale, limestone, and coal of the Allegheny
Group, then cyclic shale, siltstone, sandstone, red beds and minor limestone and coal of the
Conemaugh Group, and finally cyclic limestone, shale, sandstone, and coal of the Monongahela
Group.
Permian
Pittsburgh Low Plateau section - Cyclic sequences of sandstone, shale, limestone, and coal of the
Waynesburg, Washington, and Greene Fonnations.
Triassic-Jurassic
Eastern Gettysburg-Newark Lowland section - Fluvial arkosic sandstone, siltstone, and
conglomerate of the Stockton Formation overlain by cyclic red and black lacustrine shales and siltstones
with lithic and arkosic sandstone and conglomerate of the Lockatong Formation and Brunswick Group.
Jurassic tholeiitic Jacksonwald basalt in the upper part of the Brunswick Group and Jurassic diabase
dikes and sheets intrude the sedimentary rocks.
Central Gettysburg-Newark Lowland section - Fluvial arkosic sandstone, siltstone, and
conglomerate of the Stockton and New Oxford Formations overlain by quartose fluvial conglomeratic
sandstone of the Hammer Creek Formation.
Western Gettysburg-Newark Lowland section - Fluvial arkosic sandstone, siltstone, and
conglomerate of the New Oxford Formation overlain by red and black lacustrine shales and siltstones
with lithic, arkosic sandstone and conglomerate of the Gettysburg Formation. Jurassic tholeiitic basalts
in the upper Gettysburg Formation and Jurassic diabase dikes and sheets intrude the sedimentary rocks.
Tertiary
Reddish brown gravelly sand of the Bryn Mawr Formation is overlain by reddish brown sand with
minor gravel and silt of the Pensauken and Bridgeton Formations.
Quaternary
Gravelly sand with minor silt and clay beds of the Trenton Gravel.
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underlain by the clastic part of the sequence may vary between 120 and 270 m in elevation, with
sandstone forming the highest ridges. The Appalachian Mountains are characterized by steep,
tightly folded ridges of sandstone and deep valleys of shale and limestone. Relief on the scale of
several hundred meters is common, with elevations up to 760 m above sea level. The abrupt
transition from the Appalachian Mountain fold belt to the Appalachian Plateaus is called the
Allegheny Front
The Appalachian Plateaus Province is a broad, high-elevation plateau that is sharply
dissected by dendritic drainages. It is subdivided into the Allegheny Mountain, Mountainous High
Plateau, High Plateau, Pittsburgh Low Plateau, Glaciated Pittsburgh Plateau, Glaciated Low
Plateau, and Glaciated Pocono Plateau sections. The Allegheny Mountain and Mountainous High
Plateau consist of parallel ridges similar to those of the Appalachian Mountain section, but broader
and more dissected by dendritic drainages. Relief in these areas varies between 500 and 900 m.
The High Plateau is characterized by a broad plateau with elevations up to 760 m, with relief on the
scale of hundreds of meters produced by dendritic drainages. The Pittsburgh Low Plateau,
Glaciated Pittsburgh Plateau, and Glaciated Low Plateau are all physiographically similar, with
dendritic valleys producing relief on the scale of hundreds of meters, but maximum elevations are
on the order of 500 m. The Glaciated Pittsburgh Plateau and Glaciated Low Plateau are
differentiated from the Pittsburgh Low Plateau by the presence of glacial features. The Glaciated
Pocono Plateau is similar to the Mountainous High Plateau but has glacial features superimposed
on it.
The Eastern Lakes section of the Central Lowlands Province is an area of low relief,
sloping toward Lake Erie. It is underlain by Devonian shales and ranges from about 230 m
elevation to about 180 m at the shore of Lake Erie. The Atlantic Coastal Plain Province is
underlain by unconsolidated sediments that are mostly Tertiary and Quaternary in age and produce
low, flat hills dissected by southeast-trending stream drainages. The hills vary from about 37 to 3
meters in elevation.
Pennsylvania has a seasonal, temperate climate with warm, humid summers and cool and
snowy winters. Average temperature ranges from 22° F in January to 68° F in July with slightly
warmer temperatures in the southern portion of the State. Precipitation averages about 1016 mm
(40 in) per year statewide (fig. 3), varying between 860 and 1270 mm (34 and 50 in) regionally,
and is fairly well distributed throughout the year. In 1990, the population of Pennsylvania was
11,881,643, with 69 percent of the population living in urban areas (fig. 4). The population
density is approximately 265 persons per square mile.
GEOLOGIC SETTING AND SOILS
The following discussion of geology and soils is derived from Berg (1980), Cunningham
and others (1977), Geyer and Wilshusen (1982), and Richmond and Fullerton (1991,1992). A
general geologic map for reference is given in figure 2. It is suggested, however, that the reader
refer to the State Geologic Map of Pennsylvania by Berg (1980) or the Adas of Preliminary
Geologic Quadrangle Maps of Pennsylvania by Berg and Dodge (1981). A generalized soil map of
Pennsylvania is given in figure 5.
IV-6 Reprinted from USGS Open-FUe Report 93-292-C
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The New England Province
The New England Province in Pennsylvania is underlain by intensely faulted, sheared, and
folded Precambrian crystalline rocks of the Reading Prong (Drake, 1984). Most of the province is
underlain by granitic gneiss of igneous origin. Irregular areas of hornblende gneiss are evenly
distributed throughout the province and small irregular areas of marble and graphite-bearing
granitic gneiss occur in the western part of the province (Drake, 1967). A small tongue of the New
England Province in east-central Northampton County is characterized by a narrow band of
Franklin Marble associated with granitic gneiss, biotite gneiss, and sillimanite gneiss. Small,
irregularly distributed layers of the Cambrian Hardyston and Leithsville Formations
uncpnformably overlie or are in fault contact with the Precambrian rocks. The Hardyston consists
of quartzite and conglomerate with a thin, zircon- and thorite-rich fossil placer at the base, and the
Leithsville consists of deeply weathered dolomite with thin shaly interbeds.
Rocks underlying the New England Province tend to have deeply weathered soils (greater
than 1 meter deep) with good drainage. Granitic gneiss forms loam soils with 15-50 percent rock
fragments. These soils have moderately rapid permeability. Graphitic gneiss and hornblende
gneiss form silty loam to silty clay loam that may be very deep (tens of meters) and have moderate
permeability. Sheared fault zones in the granitic and graphitic gneiss may produce soils with rapid
permeability. The Hardyston Formation commonly caps hills and is resistant to weathering,
producing very thin pebbly and sandy soils with rapid permeability. The Leithsville Formation and
Franklin Marble form silty clay loams with moderate permeability.
Piedmont Province
The Piedmont Upland Section is underlain by complexly faulted and folded Precambrian
and Lower Paleozoic rocks. Precambrian granitic gneiss forms a prominent rock unit oriented
northeast across southeastern Chester County and northern Delaware County. It is bounded on the
east, south, and north by major faults. Granitic gneiss underlies the southern tongue of the
Piedmont Upland in Lancaster County and graphitic gneiss is a dominant rock type in the northern
half of this area, along with quartz monzonite and quartz monzonite gneiss (Crawford and
Hoersch, 1984). Granodiorite and granodiorite gneiss occupy most of the southern half of the area
and gabbroic gneiss occurs locally. Lower Paleozoic metasedimentary and meta-igneous rocks
underlie most of the southern portion of the Piedmont Upland and consist of mica schist, phyllite,
and minor hornblende gneiss of the Wissahickon Formation. A narrow belt of Setters Quartzite
and Cockeysville Marble outlines the western margin of the Precambrian gneiss in southern
Chester County. Scattered narrow belts of metabasalt and a thick belt of gray-green chlorite schist
with quartzite also occur within the Wissahickon. The Peters Creek Schist forms a broad belt that
extends northeast from the state line in southern Lancaster County and pinches out in eastern
Chester County. A narrow belt of black slate and metaconglomerate of the Peach Bottom Slate and
Cardiff Conglomerate Formations lies near the northeast edge of the Peters Creek Schist outcrop
area. Mafic gneiss forms small elongate pods with serpentinite in southeastern Chester County,
northern Delaware County, and in a narrow belt along the Maryland border. Cambrian rocks of
the Piedmont Upland include the Chickies Quartzite, greenish-gray phyllite and schist of the
Harpers Formation, and quartzite of the Antietam Formation. These units form a narrow outcrop
belt in northern Chester and eastern Lancaster Counties and comprise most of the two small
Piedmont Upland areas south of the Gettysburg-Newark Lowland in York County.
' Rocks underlying the Piedmont Upland tend to have deeply weathered soils (greater than 1
meter deep) with good to moderate drainage. Hornblende gneiss and granitic gneiss form silty to
IV-10 Reprinted from USGS Open-FUe Report 93-292-C
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sandy loams containing greater than 15 percent rock fragments. These soils hive good drainage
and moderate to moderately rapid permeability. Mica schist forms deep silty to clayey loams with
good drainage and moderate permeability. Phyllite, slate, and mafic rocks form clayey loams to
silty clays with deep soils, poor to moderate drainage, and low to moderate permeability.
The Piedmont Lowland is mostly underlain by Cambrian and Ordovician limestone and
dolomite with minor shales. The Cambrian Vintage and Kinzers Formations are dolomite and
limestone that form a narrow belt around the Piedmont Upland Cambrian sedimentary rocks,
whereas dolomite of the Ledger and Zooks Comer Formations comprise the Piedmont Lowland in
north-central Lancaster County. A narrow belt of Buffalo Springs, Snitz Creek, Schaefferstown,
and Millbach Formations, which contain more limestone than dolomite, occurs north of this central
belt The Ordovician Conestoga Formation is a limestone with shale partings that occupies most of
the Piedmont Lowland in central Lancaster County. The northern Piedmont Lowland is dominated
to the south by limestone and dolomite of the Stonehenge, Epler, Ontelaunee, Annville,
Meyerstown, and Hershey Formations and in the north by shale, phyllitic shale, and minor
sandstones of the Cocalico Formation. Soils of the Piedmont Lowlands are silty clay and silt
loams derived mostly from carbonate rocks and shales. These soils tend to be deep, with a clay
subsoil, moderate to good drainage, and slow to moderate permeability.
The Gettysburg-Newark Lowland is underlain by late Triassic-early Jurassic sedimentary
and igneous rocks of the Newark Supergroup which occur in two basins separated by a narrow
constriction (the "Narrow Neck"). The Newark basin is a wide band of sedimentary rock that
extends into New Jersey. The basal Triassic Stockton Formation and overlying Lockatong
Formation form a broad band of outcrop along the southeastern side of the basin that thins to the
southwest The Stockton consists of fluvial sandstone, siltstone, and conglomerate, and the
Lockatong consists of lacustrine black and red shales and siltstones that are interbedded with
sandstones to the southwest The Triassic-Jurassic Brunswick Group (Lyttie and Epstein, 1987)
overlies the Lockatong and forms a broad belt underlying approximately half of the basin. The
Brunswick Group consists of red and black lacustrine shales and siltstones and fluvial sandstone
and conglomerate. The Jurassic Jacksonwald basalt occurs near the top of the Brunswick Group at
the western edge of the Newark basin. The Narrow Neck is underlain by a thin band of Stockton
Formation which is overlain by conglomeratic sandstone of the Hammer Creek Formation.
The Gettysburg basin is a broad belt of rocks arching southward into Maryland. In the
Gettysburg basin, the basal Triassic New Oxford Formation crops out along the southeast margin
of the basin and consists of fluvial sandstone, siltstone, and conglomerate. The New Oxford is
overlain by the Triassic-Jurassic Gettysburg Formation, which comprises most of the basin fill.
The lower third of the Gettysburg Formation consists of fluvial red siltstones and thin sandstones.
The upper portion of the Gettysburg Formation consists of lacustrine red and black shales and
siltstones with fluvial and deltaic sandstones. The shalier unit of upper Gettysburg Formation is
called the Heidlersburg Member. Near the top of the Gettysburg Formation, Jurassic tholeiitic
basalts overlain by sedimentary rocks are restricted to two tiny areas adjacent to the border fault
Conglomerates containing clasts composed of the older rocks immediately outside of the basin
occur along the northwestern, faulted margins of both basins. The sedimentary rocks of both
basins are intruded by large Jurassic diabase dikes and sheets that are folded into broad, dish-like
synclines forming characteristic ring-shaped outcrop patterns.
Soils derived from siltstone and shale of the Gettysburg-Newark Lowland tend to be
poorly to somewhat poorly drained, have slow permeability, and form deep silty to clayey loams
and silty clays with a well-developed clay subsoil. Soils derived from sandstone and conglomerate
IV-11 Reprinted from USGS Open-File Report 93-292-C
-------
have shallow to moderately deep silty and sandy loam soils. Drainage varies from moderately
good to good and permeability varies from moderate to moderately rapid. Because of the
interlayered nature of the sediments in the basin, silt and clay layers are not uncommon within
these soils. Silt and clay loams with variable depth, drainage, and permeability are developed on
the diabase dikes and sheets of the basin. Generally these soils have good drainage (although
some have poor drainage), are moderately deep, and have slow to moderate permeability.
Blue Ridge Province
The Blue Ridge Province is underlain by Precambrian metavolcanic and Cambrian
metasedimentary rocks. The Precambrian rocks are metamorphosed and highly deformed rhyolite
and basalt with minor greenstone These rocks are overlain by slate, sandstone, and conglomerate
of the Loudoun Formation; quartzite and conglomerate of the Weverton Formation; and quartzite
and phyllitc of the Harpers Formation. The Antietam quartzite forms a narrow band along the
western and northern edge of the Blue Ridge Province and caps the ridges that define the boundary
with the Ridge and Valley Province. Dolomite of the Cambrian Tomstown Formation forms a
narrow outcrop band northwest of the Cumberland-Adams county line.
Metarhyolite, metabasalt, greenstone, and phyllite form stony colluvium with moderate
drainage and permeability, and locally form silt and clay loams and silty clays with generally poor
drainage and slow permeability. The hitter soils are deep and contain significant clay in the
subsoil. Quartzite, arkosic sandstone, and conglomerate form shallow to moderately deep soils
with good drainage and moderate to moderately rapid permeability.
Ridge and Valley Province
Half of the Great Valley section of the Ridge and Valley Province in Pennsylvania is
underlain by Cambrian and Qrdovician carbonate rocks and half by Ordovician shales and
sandstones. A narrow band of Hardyston Formation quartzite and conglomerate and Leithsville
Formation dolomite and dolomitic shale occurs along the contact with the New England Province.
These units are overlain by dolomite and minor shaly limestone of the Cambrian Allentown
Formation. The Allentown is replaced to the west by several units of limestone and dolomite.
Near the Blue Ridge Province, the Cambrian sequence consists of the Tomstown Formation
dolomite; the shale, shaly dolomite, and limestone of the Waynesboro and Elbrook Formations;
and the limestone and dolomite of the Zullinger and Shady Grove Formations.
In the eastern Great Valley, Qrdovician dolomitic carbonate rocks comprise the
Richenbach, Epler and Ontelaunee Formations, which are overlain by shaly limestone of the
Jacksonburg Formation. The Jacksonburg Formation is replaced to the north by limestone and
shaly limestone of the Annville, Meyerstown and Hershey Formations. In the area north of the
Narrow Neck, limestone of the Stonehenge Formation forms the base of the Qrdovician sequence.
Near the Blue Ridge Province, the Stonehenge Formation is overlain by limestone and minor
dolomite of the Rockdale Run Formation, Pinesburg Station Formation, St Paul Group, and
Chambersburg Formation.
The Ordovician Martinsburg Formation, consisting mostly of gray to black marine shales
with prominent layers of graywacke, makes up the youngest rocks in the Great Valley and forms a
broad belt along its northwestern edge. In the central part of the Great Valley, the belt of
Martinsburg Formation is replaced by an equivalent belt of phyllitic shale and graywacke sandstone
called the Hamburg Klippe. The northern half of the klippe is dominated by sandstones, whereas
the southern half contains numerous limestone-rich bands in phyllitic shales.
IV-12 Reprinted from USGS Open-FUe Report 93-292-C
-------
Soils of the Great Valley formed over sandstone, shale, and siltstone are generally shallow
to deep with good drainage, moderate to moderately rapid permeability, and a significant amount of
coarse fragments (>15 percent to >50 percent in loam and silty loam). Soils formed on the
carbonate rocks of the Great Valley are deep silt to clay loams with ckyey subsoils with moderately
good to good drainage and slow to moderate permeability.
The Appalachian Mountains section of the Ridge and Valley province is underlain by tightly
folded Paleozoic sandstone, shale, and limestone. Cambrian rocks are mostly restricted to the
cores of folds in a narrow belt near the western edge of the province in Bedford, Blair, and Centre
Counties. Much of the Cambrian sequence consists of dolomite and sandstone of the Gatesburg
Formation. Limestone of the underlying Warrior Formation forms narrow lenses in the cores of
some folds, and older limestone and shale of the Waynesboro and Pleasant Hill Formations are
restricted to two small areas in Blair County. Limestone of the Cambrian Shady Grove Formation
occurs in southeastern Fulton County. The Cambrian rocks are overlain by a belt of Ordovician
limestone and dolomite of the Stonehenge, Nittany, Axemann, Bellefonte, Loysburg, Snyder, and
Benner Formations. These units form the cores of a few folds in southeastern Clinton County. A
narrow belt of limestone interbedded with black shale comprises the Nealmont, Salona, and
Cobum Formations, which are overlain by gray to black shales, siltstones, and sandstones of the
Reedsville Formation. The Reedsville forms a thin band throughout the Ordovician outcrop areas
in the Appalachian Mountain section and comprises broader outcrop bands in the southeastern
corner of the section, where it overlies Ordovician carbonate rocks. Fluvial sandstone and
conglomerate of the Bald Eagle Formation and red fluvial siltstone, sandstone, and shale of the
Juniata Formation overlie the Reedsville and Martinsburg Formations, and pinch out east of the
Susquehanna River.
The Silurian-age Shawangunk Formation forms a belt of rock that unconformably overlies
the Martinsburg Formation east of the Dauphin-Schuykill county line. The Shawangunk consists
of fluvial conglomerate and sandstone that grades westward into interbedded sandstone and green
shales. To the west, the Shawangunk is laterally equivalent to well-sorted quartz sandstone of the
Tuscarora Formation and to ferruginous sandstone, oolite, and greenish-gray shale of the Clinton
Group. The Clinton Group is overlain by a narrow belt of interbedded gray shale and limestone of
the Silurian Mifflintown Formation. The Silurian Bloomsburg Formation is largely a marine
siltstone, sandstone, and shale which overlies the Mifflintown in the west and replaces the
Mifflintown to the east The Bloomsburg Formation, in turn, is overlain by a narrow belt
comprising Silurian to Devonian limestone, dolomite, quartz sandstone, and shale. In the east,
these rocks comprise the Silurian Poxono Island, Bossardville, and Decker Formations, the
Devonian Coeymans and New Scotland Formations, and the Minisink Limestone. In the west,
this sequence contains the Silurian Wills Creek and Tonoloway Formations and the Silurian-
Devonian Keyser Formation.
Overlying the Silurian-Devonian sequence is narrow belt of Devonian-age, gray marine
siltstone, shale, and argillaceous limestone with well-sorted quartz sandstone. In the east, this
comprises the Port Ewen Shale, Shriver Chert, Ridgeley and Schoharie Formations, Palmerton
Sandstone, and Buttermilk Falls Limestone. In the west, this succession makes up the Old Port
and Onondaga Formations. In the eastern part of the province, the Devonian Marcellus Formation,
consisting of marine black shale, and the Mahantango and Trimmers Rock Formations, consisting
of marine black shale interbedded with gray siltstone and sandstone, form distinct bands of
outcrop. The Trimmers Rock Formation becomes coarser to the west and is replaced by similar
shales and sandstones of the Harrell, Brallier, Scherr, and Foreknobs Formations. In the
IV-13 Reprinted from USGS Open-FUe Report 93-292-C
-------
northwestern part of the province, the Trimmers Rock is replaced by the Harrell, Brallier, and
Lock Haven Formations.
The Devonian Catskill Formation forms a broad belt of outcrop over most of the
Appalachian Mountain section and consists mostly of red siltstone, sandstone, and shale with gray
interbcds. It is overlain by a narrow band of Mississippian-age fluvial sandstone and conglomerate
of the Spechty Kopf and Pocono Formations in the east and the Rockwell and Pocono Formations
in the west. The Rockwell Formation also contains carbonaceous shale and is finer grained than
the Spechty Kopf Formation. These units are overlain by the red fluvial siltstone, sandstone, and
shales of the Mauch Chunk Formation. The Mauch Chunk underlies about 75 percent of the area
of Mississippian rocks in the Appalachian Mountains section. It is overlain by the Pennsylvania!!
Pottsville Group and Llewellyn Formation, which include gray fluvial conglomerate, sandstone,
siltstone, and shale with coal beds.
Soils of the Appalachian Mountains section formed over quartzose sandstone, shale, and
siltstone are generally shallow to deep, with good drainage, moderate to moderately rapid
permeability, and contain coarse fragments (>15 percent to >50 percent in loam and silty loam).
Colluvial soils are common. Soils formed on the carbonates and interbedded carbonate and clastic
rocks of the Appalachian Mountains are highly variable, but are generally moderately deep to deep,
sandy to clayey loams with silty to clayey subsoils, moderately good to good drainage, and slow to
moderate permeability.
Appalachian PlateausJEnoyince
The Appalachian Plateaus Province is underlain by sandstone, siltstone, and shale ranging
from Devonian to Permian in age. Marine gray sandstone, siltstone, and shale of the Lock Haven
Formation make up a large portion of the Devonian section in Tloga and Bradford Counties. It is
overlain by red siltstone, sandstone, and red to gray shale of the Devonian Catskill Formation.
The Catskill comprises all of the Devonian in this province east and south of the Lock Haven
Formation, and most of the Devonian section in Potter, Cameron, and Clinton Counties. West of
these counties, the Catskill Formation is underlain and gradually replaced by gray marine siltstone,
sandstone, and shale of the Chadakoin and Venango Formations. In the Mountainous High
Plateau, the Catskill is overlain by sandstone and minor red shale of the Mississippian Huntley
Mountain Formation, and fluvial sandstone and conglomerate of the Mississippian Burgoon
Formation. These are overlain by red fluvial siltstone, sandstone, and shale of the Mauch Chunk
Formation. A similar rock sequence occurs in the Allegheny Mountain section. To the north and
west of the Mountainous High Plateau section, the Mauch Chunk and Burgoon Formation are
missing, so that the Huntley Mountain is the only Mississippian unit underlying Tioga, Potter, and
Cameron Counties. West of this area, the Mississippian section consists of gray marine and deltaic
siltstone, shale, and sandstone of the Riceville Formation, Berea and Corry Sandstone, Cuyahoga
Group, and Shcnango Formation. The sandstone, conglomerate, shale, and coal of the
Pennsylvanian Pottsville Group forms a broad east-west belt across the northern part of the
Pennsylvanian section in the Appalachian Plateau and forms parallel bands in the Allegheny
Mountain section. Cyclic sequences of gray marine shale, siltstone, sandstone, limestone, and
coal comprise the Pennsylvanian-age Allegheny Group, Conemaugh Group, and Monongahela
Group, south of the outcrop of Pottsville rocks. The Permian rocks in the southwestern corner of
the State consist of cyclic sequences of sandstone, shale, limestone, and coal, and are divided into
the Waynesburg, Washington, and Greene Formations.
IV-14 Reprinted from USGS Open-FUe Report 93-292-C
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Most of the Appalachian Plateaus Province has soils derived from sandstone, shale and
siltstone, with two exceptions: the Glaciated Pittsburgh Plateau is underlain by soils formed on tills
and the Permian age rocks of the Pittsburgh Low Plateau have calcareous soils formed from
limestone, shale, and sandstone. Soils derived from sandstone are moderately deep silt loams
containing more than 15 percent rock fragments. Permeability is moderate to moderately rapid and
drainage is good. Soils derived from shale, limestone, and siltstone are deep, silty to clayey loams
with clayey subsoils, slow to moderate permeability, and poor to moderately good drainage.
Central Lowland Province
The Central Lowland Province in Pennsylvania is underlain by gray marine shale and
siltstone of the Devonian Northeast Shale and Girard Shale. The Northeast Shale forms a band
parallel to the Lake Erie shore and the Girard Shale forms a parallel band of equivalent width to the
southeast of it Parts of the province are covered by highly variable, sandy to clayey glacial till.
Soils are moderately well drained to poorly drained sandy loams and silty clay with moderately
rapid to slow permeability.
Atlantic Coastal Plain Province
The Atlantic Coastal Plain Province is underlain by unconsolidated sand, gravel, and clay
of Tertiary and Quaternary age. Tertiary and Cretaceous-age deposits also occur in small areas
overlying crystalline rocks of the Piedmont Province. The Cretaceous Patapsco Formation
consists of variegated clay with sand lenses and occurs in patches overlying the Piedmont Lowland
section in Montgomery County. Gravelly sand and silt of the Tertiary Bryn Mawr Formation
overlie rocks of the Piedmont Upland in irregular patches. The Tertiary Pensauken and Bridgeton
Formations comprise most of the Atlantic Coastal Plain Province. They consist of fluvial arkosic
quartz sand with pebble beds and minor clay and silt beds. The Pensauken and Bridgeton
Formations unconformably overlie the lower Paleozoic Wissahickon Formation. The belt of
Quaternary sediment near the Delaware River includes Holocene to Recent fluvial and swamp
deposits as well as gray pebbly sand, crossbedded sand, silt, and clay of the Trenton Gravel.
GLACIAL GEOLOGY
Pleistocene glaciers of the Erie-Ontario lobe advanced from the northwest across
northwestern Pennsylvania, and glaciers of the Hudson-Champlain lobe advanced from the
northeast, covering the northeastern quarter of the State (Fullerton, 1986). Glacial deposits in
Pennsylvania range in age from about 550,000 to about 12,500 years B.P. (fig. 6; Pennsylvania
Topographic and Geological Survey, 1981).
Glacial deposits in Pennsylvania can be classified into three main categories: till,
glaciofluvial deposits, and glacial lake deposits. Till is an unsorted deposit of gravel, sand, silt,
and clay, with occasional cobbles and boulders. Thickness of the till ranges from a thin,
discontinuous veneer of less than one meter to locally more than 15 meters on end moraines, but it
is generally in the range of 1-10 m thick (Richmond and Fullerton, 1991,1992). The composition
of the till typically reflects the underlying bedrock, although clasts of bedrock from many
kilometers away are common. In northern Pennsylvania, the till clasts are predominantly
sandstone, siltstone, and shale, with minor limestone and crystalline rock from New York and
Canada. The older tills (pre-late Wisconsinan) are generally silty and clayey whereas late
Wisconsinan tills are generally silty to sandy (Pennsylvania Topographic and Geological Survey,
IV-15 Reprinted from USGS Open-FUe Report 93-292-C
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GLACIAL DEPOSITS OF PENNSYLVANIA ^
EXPLANATION
(from Pennsylvania Topographic and Geologic Survey, 1981)
AGE SYMBOL NAME
°2
2 O Jfj^ STRATIFIED DRIFT
on
I
CO
O
O
CO
UJ
ASHTABULATILL
HIRAM TILL
LAVERYTILL
KENT TILL
••
CLEAN TILL
DESCRIPTION
Sand and gravel in eskers, kames, kame
terraces, and outwash, principally in valleys; silt
and clay jn lake deposits in formerly ice-dammed
valleys; lake clays and beach sands and gravels
along Lake Erie; thin (Recent) to thick (Illinoian)
soils.
Thick, gray, clayey to silty to sandy till covering
over 75 percent of the ground; topography is
mainly gently undulating, but there is also some
knob-and-kettle topography; thin soil.
Moderately thick, gray to grayish-red, sandy till
covering 25 to 50 percent of the ground; very thin
till covers an additional 25 percent of the ground;
topography reflects the underlying bedrock; thin
soil.
TITUSVILLE TILL
Thin, gray (Titusville) to grayish-red
(Warrensville), clayey to sandy till covering 10 to
WARRENSVILLE TILL 2S Percent of tne ground; topography reflects
the underlying bedrock; moderately thick, well-
developed soil.
<
O
MAPLEDALE TILL
MUNCY TILL
Thin, gray, clayey to silty till in patches
covering up to 10 percent of the ground;
topography reflects the underlying bedrock;
thick, well-developed soil often having a
yellowish-red color.
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1981). A large proportion of the soils developed on these older tills have seasonally high water
tables, slow permeability, and poor drainage. Sandy and stony till soils have good drainage with
rapid permeability. Glacial landforms typically associated with till include drumlins, ketdes, and
moraines. Moraines are ridges of till that form at the margin of a stationary or retreating glacier.
Ketfles are depressions in the till surface that form when blocks of glacial ice, buried beneath a
layer of till, melt away, causing the till to collapse into the depression. The hummocky landscape
that forms is called "knob-and-ketfle topography". Drumlins are streamlined, conical hills of till
that are oriented parallel to the direction of glacial movement
Glaciofluvial deposits are stratified sands and gravels deposited by glacial meltwater
streams. Glaciofluvial features include outwash plains, kames, kame terraces, and eskers.
Common to all types of glaciofluvial deposits are their coarse, sandy and gravelly texture, and their
stratified (bedded) nature. Coarse sand and gravel deposited by glacial meltwater streams is called
outwash and occurs in many glaciated valleys. Kames were formed where meltwater streams on
top of the glacier surface deposited sediment in depressions on the glacier's top surface. When the
glacier melted, these deposits slumped to the ground surface, forming irregular, stratified hills.
Kame terraces were formed by glacial meltwater streams that flowed between the edge of the
glacier and a valley wall. Again, when the glacier melted, the stratified deposits slumped to the
valley floor, forming irregular, elongate deposits along the sides of valleys. Eskers are long,
narrow, sinuous ridges composed of sand and gravel deposited by rivers that flowed in tunnels
underneath a stagnant ice sheet or glacier. The soils developed on glacial outwash have moderate
to good drainage and moderate to rapid permeability.
Glaciolacustrine (glacial lake) deposits consist of stratified silt and clay deposited on the
bottoms of lakes dammed by moraines or ice. Lake-bottom silt and clay deposits occur along the
shore of Lake Erie and in some valleys in northwestern Pennsylvania. Coarse-grained sediments
associated with glacial lakes include deposits of lacustrine deltas, beaches, or wave-cut outwash
terraces. Beach deposits, formed when Lake Erie was at a higher level following glaciation, are
found in Erie County. Soils developed on lake-bottom silt and clay typically have poor drainage
and slow permeability, whereas soils developed on lacustrine deltas and beaches have moderate to
good drainage and moderate to rapid permeability. Glaciolacustrine deposits are mapped with
glaciofluvial features on figure 6.
URANIUM OCCURRENCES AND AERORADIOAdTVTrY
An aeroradiometric map of Pennsylvania (fig. 7) was compiled from spectral gamma-ray
data acquired during the U.S. Department of Energy's National Uranium Resource Evaluation
(NURE) program (Duval and others, 1989). For the purposes of this report, low equivalent
uranium (eU) is defined as less than 1.5 parts per million (ppm), moderate eU is defined as
1.5-2.5 ppm, and high eU is defined as greater than 2.5 ppm. In figure 7, the Piedmont and New
England Provinces have a few areas of low radioactivity but, for the most part, eU ranges from
moderate to high. The Blue Ridge has distinctly low aeroradiometric signature, with some
moderate eU along the eastern edge of the province. The Great Valley Section has moderate to
high eU overall. The Appalachian Mountain Section is predominantly low, with lesser areas of
moderate eU and a prominent area of high eU centered over Montour County and adjacent
Columbia and Northumberland Counties. The Glaciated Pocono Plateau Section and eastern half
of the Glaciated Low Plateau Section have low to moderate eU. The western half of the Glaciated
Low Plateau Section has moderate to high eU. The High Plateau Section and much of the
IV-18 Reprinted fromUSGS Open-File Report 93-292-C
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Mountainous High Plateau has low and some moderate eU. The Glaciated Pittsburgh Plateau has
moderate eU and several areas of high eU. Moderate and high eU covers much of the Pittsburgh
Low Plateau Section. R. Smith and J. Barnes (PA Geological Survey, unpub. data) field-checked
manyof the NURE radiometric anomalies and found a correlation between some of the anomalies
and rresh bedrock at or near the surface (as opposed to actual uranium anomalies).
Uranium occurrences in Pennsylvania are widespread. The following description of the
known uranium occurrences are provided in order of rock age. Equivalent uranium concentration
. o
7' K CT n0ted where il aPPears to correlate with specific areas and is documented in the
NURE reports.
T T ^ • Reading Prong, northeast of Pikesville, McCauley (1961) described 0.2 percent
UaOg in a pegmatite associated with a magnetite ore body. Montgomery (1957) described uranium
minerals within Precambrian serpentine rock associated with the Franklin Marble near Easton The
NURE Portfolios for the Newark and Scranton Quadrangles (LKB Resources, 1978a, c)
document a number of moderate to high eU values in granitic gneiss of the Reading Prong and the
Piedmont Upland section. Equivalent uranium is especially high in the Reading Prong. A
carborne radiometric survey of the Reading Prong (Pennsylvania Topographic and Geological
Survey, 1985) recorded numerous elevated gamma-ray readings, most of which correlate with
granitic gneiss. The Pennsylvania Geological Survey (1978) observed high radioactivity
associated with many faults and shear zones in the Reading Prong. They reported 67 ppm U3O8 in
a sample from one of the shear zones.
The aeroradioactivity map (fig. 7) shows a group of high anomalies apparently associated
with serpentmite and marble units in the Piedmont Upland of eastern Northampton and central
Chester Counties and high eU associated with phyllite in the Wissahickon Formation in central
York County. The Wissahickon Formation in the Piedmont Upland section also appears to have
numerous moderate eU areas (fig. 7). The Catoctin Formation in the Blue Ridge appears to have
low eU associated with it At the Pennsylvania Topographic and Geologic Survey, J Barnes
calculated the median uranium content of 80 samples of Catoctin metabasalt and metadiabase
(delayed neutron activation analyses) and found it to be less than 0.5 ppm.
Dennison (1982) reported uranium minerals in the Hardyston Formation. Van Assendelft
and Sachs (1982) reported elevated uranium in soils (up to 5 ppm U) and elevated radon in homes
overlying dolomites of the Cambrian Leithsville Formation in Lehigh County. The NURE folios
for the Newark and Harrisburg Quadrangles (LKB Resources, 1978b, c) indicate that numerous
moderate to high eU concentrations are associated with Cambrian carbonate rocks of the Piedmont
Lowland and the Great Valley. The shaly dolomites of the Snitz Creek, Elbrook, Leithsville
Ledger, and Allentown Formations all have several areas of high eU values. LKB Resources
(1978b, c) also report several high values in the Chickies Quartzite in Lancaster County. Several
moderate eU values are reported in the Hardyston Formation in the New England and northern
Piedmont provinces. The aeroradioactivity map (fig. 7) shows a concentration of high to moderate
eU associated with the Cambrian carbonate rocks in the Piedmont Lowland and Great Valley
sections, and associated with the small Cambrian carbonate rock areas near the Allegheny Front in
the western Appalachian Mountain section. Moderate to high eU readings appear to correlate with
the Harpers Formation in the Blue Ridge Province in Franklin County.
Van Assendelft and Sachs (1982) reported elevated uranium in soils (up to 6.5 ppm U) and
elevated radon in homes overlying the Ordovician Beekmantown Group in Dauphin, Northampton,
and Cumberland Counties, and overlying the Ordovician Martinsburg Formation (4.96 ppm U in
soil) in Lehigh County. The NURE folios for the Newark, Scranton, and Harrisburg Quadrangles
IV-20 Reprinted from USGS Open-File Report 93-292-C
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(LKB Resources, 1978a, b, c) report numerous high to moderate eU anomalies' in Qrdovician
carbonates in the Piedmont Lowland, Great Valley, and Appalachian Mountain sections. The
Beekmantown Group, St Paul Group, Conestoga Formation, and the Epler and Rickenbach
Formations all have a number of high eU readings (4-6 ppm eU) in shaly limestone and dolomite.
The Coburn Formation has particularly high eU readings (up to 12 ppm) in the Appalachian
Mountain section. The black shales of the Martinsburg Formation and similar units in the
Hamburg Klippe and the Reedsvffle Formation all have numerous high eU values (commonly 5-7
ppm eU). The aeroradioactivity map of Pennsylvania (fig. 7) shows high to moderate eU values
associated with Qrdovician rocks of the Piedmont Lowland, Great Valley, and the Appalachian
Mountain sections. The sandstone unit of the Hamburg Klippe in Berks County appears to have
low to moderate eU.
The NURE folio for the Harrisburg Quadrangle (LKB Resources, 1978a) reports
numerous high to moderate eU concentrations in the Silurian limestone, dolomite, and shaly
limestone of the Tonoloway, Keyser, and Wills Creek Formations and numerous high eU values
(3-8 ppm) in the Clinton Group within the Appalachian Mountain section. The Clinton Group
anomalies may be associated with gray shales and/or hematitic sandstones. The Silurian units are
not distinguishable as moderate to high areas on the aeroradioactivity map (fig. 7), but the
Shawangunk Formation does stand out as distinctly low in radioactivity.
As many as 50 uranium prospects have been reported in the Devonian Catskill Formation
(McCauley, 1961; Schmiermund, 1977; Smith, 1980; Smith and Hoff, 1984). The uranium
occurs throughout the formation, but most of the occurrences are concentrated near the Allegheny
Front in Sullivan and Lycoming Counties. Prospects also occur in Columbia, Bradford
Wyoming, Wayne, Lackawanna, Northumberland, and Huntingdon Counties. According to van
Assendelft and Sachs (1982), lower CatskUl occurrences are mostly carbonaceous debris
associated with limestone pellets in crossbedding, and some of the upper Catskill occurrences are
larger roll-front deposits at the contact of red conglomerates with green siltstone. The latter type
contain up to 0.5 percent (5000 ppm) U. Smith and Hoff (1984) note that uranium associated with
calcareous lag gravels in the upper Catskill has a median concentration of 34 ppm UsQg (these
gravels also contain phosphatic fish fossil fragments), the overlying gray sandstone has a median
value ol 55 ppm UsOg, and associated reduced siltstone and shale beds have a median value of 39
ppm U308. Van Assendelft and Sachs (1982) report elevated radon in homes overlying the
Devonian Lock Haven Formation at the Catskill contact in Lycoming County. The NURE folios
for the Newark, Scranton, and Harrisburg Quadrangles (LKB Resources, 1978a, b, c) reported
moderate to high eU that is commonly associated with Lower Devonian carbonate rocks and black
shales of the Hamilton Group, Susquehanna Group, and the lower CatskUl Formation. Equivalent
uranium as high as 11 ppm occurs in fluvial sandstones of the Catskill Formation. The
aeroradioactivity map (fig. 7) shows Devonian rocks of the Appalachian Mountain section as
having mostly high to moderate eU and outlines the Allegheny Front boundary in the Catskill
Formation and the folds in the CatskUl Formation in Lycoming, Montour, and Northumberland
Counties. The CatskUl fluvial fades in Bradford and Tioga Counties is associated with high eU
whereas the deltaic facies of the Lock Haven Formation in Potter, McKean, Warren, and Cameron
Counties and the deltaic facies of the lower Catskill formation in Bedford and Somerset Counties
all have moderate to low eU. The Devonian Marcellus Formation has uranium concentrations as
high as 16 ppm in black carbonaceous shale, whereas the Hamilton Group, in general, has typical
concentrations of 2-3 ppm U (Pennsylvania Topographic and Geologic Survey, 1988, unpub.
IV-21 Reprinted from USGS Open-File Report 93-292-C
-------
Bucks County report). The Devonian Northeast Shale in Erie County and the Venango Shale in
Crawford County produce locally high eU.
McCauley (1961) described four occurrences of uranium in the Mississippian Mauch
Chunk Formation near the contact with the overlying Pottsville Formation. Uranium
concentrations of about 0.15-0.25 percent occur in gray sandstone and conglomerate overlying red
siltstone and shale. The nature of these occurrences, with additional references, are further
described in Sevon and others (1978), who report concentrations up to 1.8 percent U3Og (R.C.
Smith, pcrs. comm., indicates a concentration of 2.58 percent UaOg from a channel sample at
Mount Pisgah). Dennison (1982) reports a uranium show in the Mississippian Pocono Group near
Wilkes-Barre. Van Assendelft and Sachs (1982) report that uranium occurrences occur in the
Mauch Chunk near the underlying Pocono Group and overlying Pottsville Formation. The NURE
portfolios for the Scranton and Harrisburg Quadrangles (LKB Resources, 1978a, b) report
moderate eU values for the Pocono Group and high eU values (up to 6 ppm eU) for the Mauch
Chunk Formation. The aeroradioactivity map of Pennsylvania (fig. 7) appears to show moderate
to high eU values for the outcrop belt of the Mauch Chunk and low to moderate eU for the Pocono
Group.
Dennison (1982) reports uranium shows in the lower Freeport Coal of the Pennsylvanian-
age Allegheny Group in Clearfield and Beaver Counties. The NURE portfolios for the Scranton
and Harrisburg Quadrangles (LKB Resources, 1978a, b) indicate that moderate eU anomalies are
common in the Llewellyn Formation, probably associated with coals. The aeroradioactivity map of
Pennsylvania (fig. 7) shows moderate to high eU values mat appear to be associated with the lower
Allegheny Group in Butler, Clarion, and Jefferson Counties, with the lower Conemaugh Group in
Beaver, Butler, Armstrong, and Indiana Counties, and with the Monongahela Group in
Washington and Westmoreland Counties. High values in Crawford County appear to be at least
partially associated with the black shales of the Bedford and Rice Shales. The Pottsville Group is
associated with conspicuous low eU readings along the entire belt of its outcrop.
Dennison (1982) reports occurrences of apatite and monazite in the Mather sandstone lentils
of the Waynesburg Formation. Moderate eU readings appear to correlate with the Waynesburg
Formation in Washington and Greene Counties on the aeroradioactivity map of Pennsylvania
(fig 7). The Greene Formation in Greene County correlates with a conspicuous low eU area on
the map.
Three prospects of McCauley (1961) were in Triassic fluvial sandstone of the upper
Stockton Formation, where gray to black silt lenses occurred in arkosic sandstone channels.
Uranium occurrences have also been noted in the upper Stockton Formation by Turner-Peterson
(1980) and in black shales (Olsen, 1988) and gray sandstones (J.P. Smoot, unpub. data) of the
Lower Brunswick Group. The Pennsylvania Topographic and Geologic Survey (1988, unpub.
Bucks County report) discusses more than 30 uranium occurrences associated with Stockton
sandstones and from black shale of the Lockatong Formation and Brunswick Group. They report
concentrations of 5 to 35 ppm U from channel samples of these units. Geyer and others (1976)
note uraniferous mineral assemblages associated with iron ores occurring where diabase sheets
have metamorphosed Paleozoic limestones or early Mesozoic limestone conglomerates in the
vicinity of the Narrow Neck. Black shales of the Heidlersburg Member and fluvial sandstones of
the New Oxford Formation have moderate to high eU values on the NURE aeroradioactivity map
(fig. 7). The upper New Oxford Formation contains lithologic associations similar to the uranium-
bearing units in the Stockton Formation, but no uranium occurrences have been noted. The black
shales and gray sandstones of the Lockatong Formation and the Heidlersburg Member are similar
IV-22 Reprinted from USGS Open-File Report 93-292-C
-------
int ^ "SfT1? i *"? L°Wtr Brunswick ^"P'«« ^ «rani«m occurrences have been
noted Black shales and gray sandstones in the Upper Brunswick Group and upper Gettysburg
Fornmtion may also be locally uranium-rich, but no uranium occurrences have been noted. The
NURE folios for the Newark and Scranton Quadrangles (LKB Resources, 1978a, b) report
moderate to high eU in the Lower Brunswick Group and the Gettysburg shale, particularly in areas
adjacent to diabase sheets. The aeroradioactivity map of Pennsylvania (fig. 7) shows moderate to
high eU associated with the upper Stockton and New Oxford Formations and with the Lockatong
and lowermost Lower Brunswick Group and the Heidlersburg Member of the Gettysburg
rfS
i(fig.7).
INDOORRADON
Indoor radon data from 2,389 homes sampled in the State/EPA Residential Radon Survey
conducted in Pennsylvania during the winter of 1988 are shown in figure 8 and given in Table 1
A map of counties is included for reference (fig. 9). Indoor radon was measured by charcoal
canister and data are shown on figure 8 only for those counties with 5 or more data values The
maximum value recorded in the survey was 273.5 pO/L in Dauphin County. The average for the
State was 7.5 pCi/L and 39 percent of the homes tested had indoor radon levels exceeding
4 pQ/L Counties with maximum indoor radon levels greater than 100 pCi/L include Beaver
Cumberland, Dauphin, Elk, Lancaster, Lebanon, Potter, Union, and York Counties (Table 1)'
The highest percentage of homes with indoor radon levels over 4 pCi/L appear to be associated
with rocks of the Great Valley section, the Piedmont Uplands and Lowlands, parts of the
Appalachian Mountain section along the Allegheny Front and in the northern counties, the western
Glaciated Low Plateau section, and the Pittsburgh Low Plateau section. The majority of counties
in Pennsylvania have average radon concentrations greater than 4 pCi/L. Counties with an average
kss than 4 pCi/L include Wayne, Lackawanna, and Luzerne Counties in the Glaciated Pocono
SSTi ^ 6~tem Glaciated L™ Plateau> ^ northernmost Appalachian Mountain section-
Philadelphia, Delaware, and Montgomery Counties in the Atlantic Coastal Plain, the Gettysbure-
Newark Lowland, and in the easternmost Piedmont Upland; Huntington County in the southern
Appalachian Mountain section; Cambria County in the Allegheny Mountains; Washington, Greene
Crawford, and Lawrence Counties in the Glaciated Pittsburgh Plateau and the Pittsburgh Low '
Plateau sections; and McKean County in the High Plateau section.
Non-random indoor radon data compiled by EPA Region 3 from homeowners and vendors
of radon test kits for over 68,000 homes is presented in figure 10. Non-random (volunteer) indoor
radon data tend to be biased toward higher values compared to randomly sampled surveys because
it is more likely that many of the data points are from homeowners that tested their homes after
receiving word of a nearby high value. However, these data do appear to further emphasize the
areas of low and high radon in the State and provide some distinction within the higher radon
categories. The Great Valley section and Piedmont and New England Provinces appear to have the
greatest percentage of homes with indoor radon levels greater than 4 pCi/L.
IV-23 Reprinted from USGS Open-FUe Report 93-292-C
-------
-------
Bsmt. & 1st Floor Rn
%>4pCi/L
OtolO
11 to 20
21 to 40
41 to 60
61 to 80
81 to 100
Missing Data
»nw»il£j bf«4m
or < 5 measurements
100 Miles
Bsmt. & 1st Floor Rn
Average Concentration (pCi/L)
0.0 to 1.9
2.0 to 4.0
4.1 to 10.0
10.1 to 36.2
3 Q Missing Data
or < 5 measurements
Figure 8. Screenmg indoor radon data from the EPA/State Residential Radon Survey of
Pennsylvania, 1987-88, for counties with 5 or more measurements. Data are from 2-7 dav
charcoal canister tests. Histograms in map legends show the number of counties in each
category The number of samples in each county (See Table 1) may not be sufficient to
statistically characterize the radon levels of the counties, but they do suggest general trends
Unequal category intervals were chosen to provide reference to decision and action levels '
-------
-------
TABLE 1. Screening indoor radon data from the EPA/State Residential Radon Survey of
Pennsylvania conducted during 1987-88. Data represent 2-7 day charcoal canister measurements
from the lowest level of each home tested.
COUNTY
ADAMS
ALLEGHENY
ARMSTRONG
BEAVER
BEDFORD
BERKS
BLAIR
[BRADFORD
BUCKS
BUl'JLER
CAMBRIA
CAMERON
CARBON
CENTRE
[CHESTjjK
CLARION
CLEARFffiLD
CLINTON
COLUMBIA
CRAWFORD
CUMBERLAND
DAUPHIN
DELAWARE
ELK
ERIE
FAYK1TE
FOREST
FRANKLIN
FULTON
GREENE
HUNTINGDON
INDIANA
JisM-ERSON
JUNIATA
LACKA WANNA
LANCASTER
LAWRENCE
LEBANON
LEfflGH
LUZERNE
LYCOMING
NO. OF
MEAS.
26
261
15
120
14
40
32
40
46
97
42
5
18
22
34
13
28
7
10
-f
49
39
17
70
28
3
20
3
7
7
17
14
5
81
69
56
21
23
118
28
MEAE
6.8
47
6.2
7.9
8.5
9.9
4.0
7.8
4.6
8.8
3.8
3.7
8 3
14.1
9.9
4.0
5.3
Q4
17.5
2.8
20.6
22.8
2.7
18.9
4.8
47
1.8
12.4
28.2
2.7
4.3
5.3
6.7
3.3
3.0
14.0
3.6
22.8
16.1
3.5
10.7
IGEOM.
I MEAN
2.7
•) /
3.8
4.3
5.3
5.0
2.4
4.1
2.9
4.1
2.4
2.1
A *
8.8
3.8
2.5
2.9
9 1
7.7
1.9
10.6
7.2
1.3
2.5
1.8
*?4
1.5
7.6
16.2
1.5
3.3
2.8
4.6
2.2
1.9
9.5
2.4
12.6
9.1
2.4
4.1
MEDIAN
2.4
t A
2.A
3.6
3.7
5.5
5.8
2.4
4.8
2.9
4.0
2.0
1.4
3*7
./
8.2
3.5
2.9
2.91
o o
X.V
8.3
1.6
11.0
9.4
1.4
2.1
1.4
10
.6
1.5
10.8
15.8
2.3
3.0
1.9
5.9
1.7
1.6
9.3
2.4
11.5
8.5
2.3
3.3
STD.
DEV.
14.9
9.1
6.5
12.5
7.9
12.6
5.0
9.9
5.4
12.3
4.4
3:9
10.5
19.6
15.3
4.6
«-5
17.7
27.6
2.8
28.8
46.9
4.5
62.6
7.9
6.2
1.1
11.3
32.1
2.2
3.1
7.0
5.3
3.7
4.7
16.0
3.5
41.3
18.6
3.7
20.0
MAXIMUM
76.*
91.9
24.7
103.5
25.8
68.2
26.1
50.0
33.2
74.5
19.2
9.5
42.5
89.2
64.3
17.8
45.0
49.0
91.9
11.3
156.3
273.5
26.4
260.9
45.9
22.0
3.0
45.5
64.6
5.8
9.8
26.0
19.9
9.7
40.0
105.7
18.0
196.7
78.0
222
77.4 _
%>4pCi/L
35
2*
47
46
64
63
28
58
33
50
24
40
50
82
38
39
29
43
60
19
78
61
13
18
30
25
0
65
100
29
43
35
57
20
20
87
29
86
87
43
%>20 pCi/L
4
3
11
7
3
g
2
16
o
0
6
9
18
0
4
14
20
— 2J
29
22
3
12
6
7
0
15
33
1
JiJ
6
0
0
16
0
24
26
1
11
-------
TABLE 1 (continued). Screening indoor radon data for Pennsylvania.
COUNTY
MCKEAN
MERCER
MBFFLIN
MONROE
MONTGOMERY
MONTOUR
NORTHAMPTON
NORTHUMBERLAND
PERRY
pHTT.AnKT.PHTA
PIKE
POTTER
SCHUYUOLL
SNYDER
SOMERSET
SULLIVAN
SUSQUEHANNA
TIOGA
UNION
VENANGO
WARREN
WASHINGTON
WAYNE
WESTMORELAND
WYOMING
YORK
NO. OF
MEAS.
15
51
10
55
60
6
26
15
6
125
8
12
32
6
23
1
20
29
8
27
15
45
31
72
12
68
MEAN
3.2
4.9
6.3
8.3
32
15.6
12.5
11.0
10.7
2.3
5.4
35.3
13.6
13.7
3.8
6.1
4.7
8.4
36.2
6.2
5.0
3.6
3.0
43
5.6
15.5
GEOM.
MEAN
1.5
22
2.8
4.4
2.3
62
8.0
5.2
2.4
1.4
2.8
5.3
5.0
•6.3
2.1
6.1
2.9
2.5
8.5
3.0
22
2.1
1.4
2.7
2.3
7.5
MEDIAN
1.9
1.9
1.9
4.4
2.4
4.7
7.5
4.8
2.9
1.5
4.6
3.4
4.8
8.0
2.6
6.1
2.6
1.6
7.9
2.5
1.8
1.8
1.3
32
1.8
6.6
STD.
DEV.
4.7
13.2
11.1
10.7
2.6
28.4
13.1
19.7
16.2
3.8
5.6
76.4
18.9
18.1
5.6
***
5.0
16.1
82.6
9.9
7.6
4.3
4.6
4.8
13.1
24.6
MAXIMUM
19.0
93.4
37.3
63.5
13.1
73.6
51.9
79.7
41.5
37.7
16.4
227.2
73.4
49.4
27.0
6.1
17.4
70.1
240.4
47.5
29.9
20.5
22.8
34.3
47.2
155.6
%>4pCi/L
27
18
30
53
28
67
89
53
33
11
50
42
56
67
17
100
35
35
75
30
33
22
23
38
8
68
%>20pCi/L
0
4
10
11
0
17
15
7
17
1
0
17
22
17
4
0
0
17
13
7
7
2
3
1
8
21
-------
RT
« si
oo
§
09
1
01
I
-------
-------
GEOLOGIC RADON POTENTIAL '
A number of studies have been done on the correlation of indoor radon with geology in
Pennsylvania. The Reading Prong is the most notable example because of the national publicity
surrounding a particularly severe case of radon (Smith and others, 1987). These authors and
others (Gundersen and others, 1988; Agard and Gundersen, 1991; Gundersen, 1991) found that
shear zones within the Reading Prong rocks enhanced the radon potential of the rocks and created
local occurrences of very high uranium and indoor radon. Several of the rock types in the Reading
Prong are highly uraniferous and are the source for high radon levels throughout much of the New
England Province. Smith and others (1987) report a median of 81 ppm U for47 granite-hosted
occurrences in the Reading Prong. Very high indoor radon levels have been found throughout the
Reading Prong (R.C. Smith, pers. comm.).
Some rocks within the Piedmont have high geologic radon potential and are associated with
high indoor radon and high radioactivity. Rock types in the Piedmont with some naturally elevated
uranium concentrations include granitic gneiss, biotite schists, and gray phyllites. Phyllites and
schists in other parts of the Piedmont, such as the Wissahickon Formation and Peters Creek Schist
equivalents in Maryland and Virginia, shear zones in these rocks, and the faults surrounding mafic
bodies within these rocks are known sources of radon and have high indoor radon associated with
them (Gundersen and others, 1988; Otton and others, 1988).
Carbonate rocks of the Great Valley and Appalachian Mountain section have been the focus
of several studies (van Assendelft and Sachs, 1982; Gross and Sachs, 1982; Greeman and Rose
1990; Luetzelschwab and others, 1989), and the carbonate rocks in these areas produce soils with
high uranium and radium contents and high soil-gas radon concentrations. In general, indoor
radon in these areas is higher than 4 pCi/L and the geologic radon potential of the area is high
especially in the Great Valley where the average indoor radon is distinctly higher than in
surrounding areas. The limestone and dolomite distribution in Pennsylvania is shown in figure 11
(Pennsylvania Topographic and Geological Survey, 1990). Limestone and dolomite rock at the
surface in the Great Valley, Appalachian Mountains, and Piedmont are probably sources of high
indoor radon. Carbonate rocks themselves are usually low in radionuclide elements, but the soils
developed from carbonate rocks are often elevated in uranium and radium. Carbonate soils are
derived from the dissolution of the CaCOs that makes up the majority of the rock. When the
CaCOs has been dissolved away, the soils are enriched in the remaining impurities, predominantly
base metals, including radionuclides. Studies in the carbonates of the Great Valley in West
Virginia suggest that the deepest, most mature soils have the highest radium concentrations
(Schultz and Wiggs, 1989; Schultz and others, 1992). Rinds containing high concentrations of
uranium and uranium minerals can be formed on the surfaces of rocks involved in CaCOs
dissolution and karstification. Karst and cave morphology is also thought to promote the flow and
accumulation of radon.
The clastic rocks of Pennsylvania, particularly some of the black to gray shales and fluvial
sandstones of the Newark basin and many of the Ordovician through Pennsylvanian-age black to
gray shales and fluvial sandstones, have been extensively cited in the literature (as referenced in the
uranium occurrences and aeroradioactivity section above) for their uranium content as well as their
general uranium potential. Data from Luetzelschwab and others (1989) indicate that gray shales
can be effective emanators of radon. Van Assendelft and Sachs (1982) list an extensive table of
indoor radon and associated geologic units in Pennsylvania. It appears from the uranium and
radioactivity data and comparison with the indoor radon data that the black shales of the Ordovician
IV-29 Reprinted from USGS Open-File Report 93-292-C
-------
-------
O\
CO
00
o
8
o
•g
CO
.a
f
00
I
CO
I
I
o
03
£
"3
T3
CO
00
-------
-------
Martinsburg Formation, the lower Devonian black shales, Pennsylvanian black shales of the
Allegheny Group, Conemaugh Group, and Monogahela Group, and the fluvial sandstones of the
Devonian Catskill and Mississippian Mauch Chunk Formation may be the source of most moderate
to high indoor radon levels in the Appalachian Plateau and parts of the Appalachian Mountains
section.
Studies in the Newark Basin of New Jersey (Szabo and Zapecza, 1991; Muessig, 1989)
indicate that the black shales of the Lockatong and Passaic Formations and fluvial sandstones of
the Stockton Formation are a significant source of radon in indoor air and in water. Where these
rock units occur in Pennsylvania, they may be the source of high indoor radon as well. Black
shales of the Heidlersburg Member and fluvial sandstones of the New Oxford Formation may also
be sources of locally moderate to high indoor radon in the Gettysburg Basin, although uranium
occurrences have not been found. Diabase sheets and dikes within the basins have low eU. The
Mesozoic basins as a whole, however, are variable in their geologic radon potential. The Narrow
Neck area is distinctly low in radioactivity (fig. 7) and Montgomery County, which is underlain
almost entirely by Mesozoic basin rocks, has an indoor radon average less than 4 pCi/L. Other
counties underlain partly by the Mesozoic basin rocks, however, have average indoor radon greater
than 4 pCi/L. The Newark basin is high in radon potential whereas the Gettysburg basin is low to
locally moderate. For the purposes of this report the basins have been subdivided along the
Lancaster-Berks county line. The Newark basin comprises the Mesozoic rocks east of this county
line.
Only a few areas in Pennsylvania appear to have geologically low to moderate radon
potential. Somerset and Cambria Counties, in the Allegheny Mountain section, have indoor radon
averages less than 4 pCi/L, and it appears that low radioactivity and low son permeability may be
factors in the moderate geologic radon potential of this area. These two counties and most of the
Allegheny Mountain section are underlain by Pennsylvanian-age sedimentary rocks. The
radioactivity map shows low to moderate radioactivity for the Pennsylvanian-age rocks in the
Allegheny Mountain section and much higher radioactivity in the Pittsburgh Low Plateau section.
Most of the reported uranium occurrences in these rocks appear to be restricted to the north and
west of the Allegheny Mountain section. Approximately half of the soils developed on these
sediments have low permeability and seasonally high water tables.
The Greene Formation in Greene County appears to correlate with distinctly low
radioactivity in figure 7. The indoor radon for Greene County averages less than 4 pCi/L for the
few measurements in the State/EPA survey. The nonrandom indoor radon shown in figure 10
shows that Greene (57 measurements) and adjacent Fayette County (223 measurements) have less
than 20 percent of the measurements over 4 pCi/L. Philadelphia and Delaware Counties, in the
southeastern corner of the State, have average indoor radon less than 4 pCi/L and have low
radioactivity. Part of Delaware County and most of Philadelphia County are underlain by Coastal
Plain sediments with low uranium concentrations. Soils developed on these sediments are
variable, but a significant portion are clayey and have low permeability.
The Blue Ridge Province is underlain by metasedimentary and metavolcanic rocks. A
distinct low area of radioactivity is associated with the province (fig. 7), although phyllite of the
Harpers Formation may be uraniferous. The soils generally have variable permeability. The
metavolcanic rocks in this province have very low uranium contents. It is difficult, given the
constraints of the indoor radon data, to associate the high average indoor radon in counties
underlain by parts of this province with specific rock units. When the indoor radon data are
examined at the zip code level, it appears that most of the high indoor radon levels are associated
IV-31 Reprinted from USGS Open-File Report 93-292-C
-------
with the Valley and Ridge (R.C. Smith, pers comm.). Therefore, the Blue Ridge is provisionally
ranked low in geologic radon potential, though this cannot be verified with presently existing data.
Radiometric lows and relatively lower indoor radon levels appear to be associated with the
glaciated areas of the State, particularly the eastern portion of the Glaciated Low Plateau and
Pocono Plateau in Wayne, Pike, Monroe, and Lackawanna Counties. Glacial deposits are
problematic to assess for radon. Li some areas of the glaciated portion of the United States, glacial
deposits enhance radon potential, especially where the deposits have high permeability and are
derived from uraniferpus source rocks. In other portions of the glaciated United States, glacial
deposits blanket more uranif erous rock or have low permeability and low radon potential. The
northeastern corner of the State is covered by the Clean Till, made up of 80-90 percent sandstone
and siltstone clasts with minor shale, conglomerate, limestone, and crystalline clasts (Richmond
and Fullerton, 1992). A large proportion of the soils developed on this till have seasonally high
water tables and poor drainage, but some parts of the till soils are stony and have good drainage
and high permeability. Low to moderate indoor radon and radioactivity in this area may be due to
the seasonally saturated ground and to the tills being made up predominantly of sandstones and
siltstones with low uranium contents. A similar situation exists in the northwestern part of the
State, which is covered by a wide variety of tills, predominantly the Kent Till, which is made up of
sandstone, siltstone, and shale clasts. Many of the soils in this area also have low permeabilities
and seasonally high water tables. Where the tills are thinner, the western portion of the Glaciated
Low Plateau has higher indoor radon levels and high radioactivity.
SUMMARY
For the purpose of this assessment, Pennsylvania has been divided into fifteen geologic
radon potential areas and each area assigned a Radon Index (RI) and a Confidence Index (CI) score
(Table 2). The RI is a relative measure of radon potential based on geology, soil, radioactivity,
architecture, and indoor radon data, as outlined in the preceding sections. The CI is a measure of
the confidence of the RI assessment based on the quality and quantity of the data used to assess
geologic radon potential See the Introduction chapter to this regional book for more information.
Analysis of the geology, radioactivity, and indoor radon data indicate that many of the
soils, surficial deposits, and rocks of the State have the potential to generate indoor radon
concentrations exceeding 4 pCi/L. Rocks, soils, and surficial deposits of the Atlantic Coastal
Plain, Gettysburg Basin, and the Blue Ridge Province have generally low radon potential. Areas
of variable or moderate radon potential include rocks, soils, and surficial deposits of the Allegheny
Mountain Section, the Glaciated Pittsburgh Plateau Section, the Central Lowland Province, the
High Plateau Section, the eastern portion of the Glaciated Low Plateau Section, the Glaciated
Pocono Plateau Section and the Permian rocks and residual soils of the Pittsburgh Low Plateau.
This is a generalized assessment of the State's geologic radon potential and there is no
substitute for having a home tested. The conclusions about radon potential presented in this report
cannot be applied to individual homes or building sites. Indoor radon levels, both high and low,
can be quite localized, and within any radon potential area there will likely be areas with higher or
lower radon potential than assigned to the area as a whole. Any local decisions about radon should
DQJ be made without consulting all available local data. For additional information on radon and
how to test, contact your State radon program or EPA regional office. More detailed information
on state or local geology may be obtained from the state geological survey. Addresses and phone
numbers for these agencies are listed in chapter 1 of this booklet
TV-32 Reprinted from USGS Open-File Report 93-292-C
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TABLE 2. RI and CI scores for geologic radon potential areas of Pennsylvania.
Mew England Province
(Reading Prong)
FACTOR RI CI
INDOORRADON 3 3
RADIOACTIVITY 3 3
GEOLOGY 3 3
SOIL PERM. 3 3
ARCHITECTURE 3
GFE POINTS 0
RANKING High High
Appalachian Mountain
Section
FACTOR RI CI
INDOORRADON 3 3
RADIOACTIVITY 2 3
GEOLOGY 2 3
SOIL PERM. 2 3
ARCHITECTURE 3
GFE POINTS 0
RANKING High High
Glaciated
Pittsburgh Plateau/
Central Lowland
FACTOR RI CI
INDOORRADON 2 2
RADioAcnvrrY 2 3
GEOLOGY 2 3
SOIL PERM. 2 3
ARCHITECTURE 3
GFE POINTS 0
TOTAL 11 11
RANKING Mod High
Mountainous High
Plateau
FACTOR RI ci
INDOORRADON 3 3
RADIOACTIVITY 2 3
GEOLOGY 2 3
SOIL PERM. 2 3
ARCHITECTURE 3
GFE POINTS 0
TOTAL 12 12
RANKING High High
.Piedmont 6i
Upland/Lowland
RI CI
3 3
3 3
2 3
3 3
3
0
Wit
1Z
High High
Allegheny
Mountain Section
RI a
2 3
2 3
2 3
2 3
3 -
0
Mod High
High Plateau
Section
RI Q
2 3
1 3
2 3
2 3
3
0
Newark
Basins
RI CI
2 1
23
3 3
2 3
3
0
12 10
High High
Pennsylvania rocks
of the Pittsburgh
Low Plateau
RI CI
3 3
3 3
3 3
2 3
3
0
14 12
High High
Glaciated
Low Plateau
Western Portion
RI CI
3 3
3 3
2 3
2 3
3
0
Great Valley
Section
RI CI
3 3
2 3
3 3
2 3
3
+2
15 12
High High
Permian rocks
of the Pittsburgh
Low Plateau
RI CI
2 3
2 3
2 3
2 3
3
0
11 12
Mod High
Glaciated
Low Plateau East
& Pocono Plateau
RI CI
2 3
2 3
2 3
1 3
3
0
Mod High High High Mod High
Blue Ridge Atlantic
Gettysburg basin Coastal Plain
RI CI PT or
1 1
1 3
2 3
1 3
3
0
8 10
1
1
1
2
3
0
8
Low High Low
3
2
3
3
11
High
IV-33 Reprinted from USGS Open-File Report 93-292-C
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TABLE 2 (continued).
RADON INDEX SCORING:
Probable screening indoor
Radon potential category Point range radon average for area
LOW 3-8 points <2pO/L
MODERATE/VARIABLE 9-11 points 2 - 4 pCi/L
HIGH > 11 points > 4 pCi/L
Possible range of points = 3 to 17
CONFIDENCE INDEX SCORING:
LOW CONFIDENCE 4-6 points
MODERATE CONFIDENCE 7-9 points
HIGH CONFIDENCE 10 - 12 points
Possible range of points = 4 to 12
IV-34 Reprinted from USGS Open-File Report 93-292-C
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REFERENCES CITED IN THIS REPORT
AND GENERAL REFERENCES RELEVANT TO RADON IN PENNSYLVANIA
Agard, S.S., and Gundersen, L.C.S., 1991, The geology and geochemistry of soils in Boyertown
and Easton, Pennsylvania, in Gundersen, L.C.S., and Wanty R.B., eds., Field Studies of
Radon in Rocks Soils and Water: U.S. Geological Survey Bulletin 1971, p. 50-62.
Banwell, G.M., and Parizek, RJL, 1985, Relationship between 4Re, 222Rn, and lineaments:
Eos, Transactions, American Geophysical Union, v. 66, p. 1115.
Banwell, G.M., and Parizek, RJL, 1986, Potential for permeability characterization of crustal
fracture zones using helium-4 and radon-222 concentrations in groundwater and soil gas:
Geological Society of America, Abstracts with Programs, v. 18, p. 534.
Banwell, G.M., and Parizek, R.R., 1988, Helium-4 and radon-222 concentrations in groundwater
and soil gas as indicators of zones of fracture concentration in unexposed rock: Journal of
Geophysical Research, v. 93, p. 355-366.
Berg, T.M., compiler, 1980, Geologic map of Pennsylvania: Pennsylvania Topographic and
Geological Survey, 4th ser., scale 1:250,000.
Berg, T.M., and others, 1989, Physoigraphic provinces of Pennsylvania: Pennsylvania
Topographic and Geological Survey, 4th ser., Map 13,2nd edition, scale 1:2,000,000.
Berg, T.M., and Dodge, CM., 1981, Atlas of preliminary geologic quadrangle maps of
Pennsylvania: Pennsylvania Topographic and Geological Survey, 4th ser., Map 61,636 p.
Cecil, L.D., Smith, R.C., H, Reilly, M.A., and Rose, W.A., 1987, Radium-228 and radium-226
in the ground water of the Chickies Formation, southeastern Pennsylvania, in B. Graves,
ed., Radon, radium, and other radioactivity in ground water: Chelsea, Michigan Lewis '
Publishers, p. 437-447.
Cohen, B., and Gromicko, R, 1988, University of Pittsburgh measurements in New Jersey and
eastern Pennsylvania, in WJ. Makofske and M.R. Edelstein, ed., Proceedings of Radon
and the Environment, Mahwah, NJ, May 8-10,1986, p. 56-61.
Cohen, B.L., 1988, Dissociation between lung cancer and a geological outcrop-discussion and
reply: Health Physics, v. 54, p. 224-226.
Cohen, B.L., KulwicM, D.R., Warner, K.R., Jr., and Grassi, C.L., 1984, Radon concentrations
inside public buildings in the Pittsburgh area: Health Physics, v. 47, p. 399-405.
Crawford, W.A., and Hoersch, A.L., 1984, The geology of the Honey Brook Upland,
southeastern Pennsylvania: in Bartholomew, M.J., ed., The Grenville event in the
Appalachians and related topics: Geological Society of America Special Paper 194
p. 111-125.
IV-35 Reprinted from USGS Open-File Report 93-292-C
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Cunningham, R.L., Ciolkosz, E.J., Petersen, G.W., and others, 1977, Soils of Pennsylvania:
Pennsylvania State University College of Agriculture Progress Report 365, University
Park, 24 p.
Dennison, J.M., 1982, Uranium favorability of nonmarine and marginal marine strata of late
Precambrian and Paleozoic age in Ohio, Pennsylvania, New Jersey, and New York: U.S.
Department of Energy, National Uranium Resource Evaluation Report GJBX-50 (82),
254 p.
Dixon, K.L., and Lee, R.G., 1987, Radon survey of the American Water Works system, in B.
Graves, ed., Radon, radium, and other radioactivity in ground water Chelsea, Michigan,
Lewis Publishers, p. 311-346.
Drake, A.A., Jr., 1967, Geologic map of the Easton Quadrangle, New Jersey-Pennsylvania: U.S.
Geological Survey Quadrangle Map GQ-594, scale 1:24,000.
Drake, A A., Jr., 1984, The Reading Prong of New Jersey and eastern Pennsylvania - An
appraisal of rock relations and chemistry of a major Proterozoic terrane in the Appalachians:
in Bartholomew, M.J., ed., The Grenville event in the Appalachians and related topics:
Geological Society of America Special Paper 194, p. 75-109.
Duval, J.S., 1987, Identification of areas with potential for indoor radon hazard using gamma-ray
measurements of surface uranium, potassium and thorium concentrations: Geological
Society of America, Abstracts with Programs, v. 19, p. 82.
Duval, J.S., Jones, WJ., Riggle, F.R., and Pitkin, J.A., 1989, Equivalent uranium map of
conterminous United States: U.S. Geological Survey Open-File Report 89-478,10 p.
Facts on File Inc., 1984, State Maps on File.
Fakundiny, R.H. and Friedman, G.M., 1988 , Workshop on geology and radon: Northeastern
Environmental Science, v. 7, p. 63-69.
Fleischer, R.L., 1986, A possible association between lung cancer and a geological outcrop:
Health Physics, v. 50, p. 823-827.
Fullerton, D.S., 1986, Stratigraphy and correlation of glacial deposits from Indiana to New York
and New Jersey, in Sibrava, V., Bowen, D.Q., and Richmond, G.M., eds., Quaternary
glaciations in the northern hemisphere: Quaternary Science Reviews, v. 5, p. 23-36.
Gaermcr, J., 1987, Commonwealth of Pennsylvania radon monitoring program, in Radon and the
Environment Conference, 1986, Proceedings: Mahwah Ramapo College of New Jersey,
p. 367-373.
George, A.C., and Eng, J., 1983, Indoor radon measurements in New Jersey, New York, and
Pennsylvania: Health Physics, v. 45, p. 397-400.
IV-36 Reprinted from USGS Open-File Report 93-292-C
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Gerusky, T., 1987, The Pennsylvania radon story: Journal of Environmental Health, v. 49,
p. 197-200.
Gerusky, T.M., 1987, Pennsylvania; protecting the home front: Environment, v. 29, p. 12,14
16,35-37.
Geyer, A.R., Smith, R.C., H, and Barnes, J.H., 1976, Mineral collecting in Pennsylvania:
Pennsylvania Geological Survey General Geology Report 33,260 p.
Geyer, A.R., and Wilshusen, J.P., 1982, Engineering characteristics of the rocks of
Pennsylvania-Environmental geology supplement to the state geologic map: Pennsylvania
Topographic and Geological Survey, 4th ser., Environmental Geology Report 1,300 p.
Greeman, DJ., and Rose, A.W., 1990, Form and behavior of radium, uranium, and thorium in
central Pennsylvania soils derived from dolomite: Geophysical Research Letters v 17
p. 833-836. ' ' '
Gross, S., and Sachs, H.M., 1982, Regional (location) and building factors as determinants of
indoor radon concentrations in eastern Pennsylvania: Princeton University, Center for
Energy and Environmental Studies Report 146,117 p.
Gundersen, L.C.S., 1991, Radon in sheared metamorphic and igneous rocks, in Gundersen,
L.C.S., and Wanty R.B., eds., Geologic and Geochemical Field Studies of Radon in
Rocks, Soils, and Water; U.S. Geological Survey Bulletin 1971, p. 38-49.
Gundersen, L.C.S., Reimer, G.M., and Agard, S.S., 1987 , Geologic control of radon in
Boyertown and Easton, PA: Geological Society of America, Abstracts with Programs
v. 19, p. 87.
Gundersen, L.C.S., Reimer, G.M., and Agard, S.S., 1988 , Correlation between geology, radon
in soil gas, and indoor radon in the Reading Prong, in M. A. Marikos and R.H. Hansman,
eds., Geologic causes of natural radionuclide anomalies: Proceedings of GEORAD
conference, St Louis, MO, United States Apr. 21-22,1987, Missouri Department of
Natural Resources, Special Publication 4, p. 91-102.
Gundersen, L.C.S., Reimer, G.M., Wiggs, C.R., and Rice, C.A., 1988, Radon Potential of
Rocks and Soils in Montgomery County, Maryland: U.S. Geological Survey
Miscellaneous Field Studies Map 88-2043, scale 1:62,500.
Hoskins, D.M., 1988, Radon; the Pennsylvania perspective: Northeastern Environmental
Science, v. 7, p. 6.
Hutter, A.R., and Rose, A.W., 1987, Radon variability in soil gases over fracture traces in
limestones, central Pennsylvania: Geological Society of America, Abstracts with
Programs, v. 19, p. 90.
Hutter, A.R., 1987, Radon variability in soil gas over fracture traces: University Park, PA,
Master's thesis, Pennsylvania State University, 156 p.
IV-37 Reprinted from USGS Open-File Report 93-292-C
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Korncr, L.A., 1977, Radon in stream and ground waters of Pennsylvania as a Reconnaissance
exploration technique for uranium deposits: University Park, PA, Master's thesis,
Pennsylvania State Univ., 151 p.
LKB Resources, Inc., 1978a, NURE aerial gamma-ray and magnetic reconnaissance survey,
Scranton quadrangle: U.S. Department of Energy NURE Report GJBX-32 (78), 126 p.
LKB Resources, Inc., 1978b, NURE aerial gamma-ray and magnetic reconnaissance survey,
Harrisburg quadrangle: U.S. Department of Energy NURE Report GJBX-33 (78), 128 p.
LKB Resources, Inc., 1978c, NURE aerial gamma-ray and magnetic reconnaissance survey,
Newark quadrangle: U.S. Department of Energy NURE Report GJBX-16 (78), 97 p.
Luetzelschwab, J.W., Helwick, KX., and Hurst, K.A., 1989, Radon concentrations in five
Pennsylvania soils: Health Physics, v. 56, p. 181-188.
Lyttle, P.T., and Epstein, J.B., 1987, Geologic map of the Newark 1° x 2° Quadrangle, New
Jersey, Pennsylvania, and New York: U.S. Geological Survey Miscellaneous
Investigations Map 1-1715, scale 1:250,000.
McCauley, J.F., 1961, Uranium in Pennsylvania: Pennsylvania Geological Survey, 4th ser.,
Mineral Resources Report 43,71 p.
Montgomery, A., 1957, Three occurrences of high thorian uraninite near Easton, Pennsylvania:
American Mineralogist, v. 42, p. 804-820.
Muessig, K.W., and Bell, C, 1988, Use of airborne radiometric data to direct testing for elevated
indoor radon: Northeastern Environmental Science, v. 7, p. 45-51.
Muessig, K.W., 1989, Uranium cycling in the crust and its relationship to radon hazards in New
Jersey: Geological Society of America, Abstracts with Programs, v. 21, p. 53.
Neiheisel, J., and Battist, L., 1987, Contributory role of Mesozoic tectonic events to radon
sources in the Appalachian region: Geological Society of America, Abstracts with
Programs, v. 19, p. 120.
Olsen, P.E., 1988, Continuity of strata in the Newark and Hartford basins, in Froelich, A J., and
Robinson, G.R., Jr., eds., Studies of the Early Mesozoic Basins of the Eastern United
States: U.S. Geological Survey Bulletin 1776, p. 6-18.
Otton, J.K., 1989, Using geology to map and understand radon hazards in the United States, in
U.S. Geological Survey Yearbook, fiscal year 1988: U.S. Geological Survey, p. 52-54.
Otton, J.K., Schumann, R.R., Owen, D.E., Thurman, N., and Duval, J.S., 1988, Map showing
radon potential of rocks and soils in Fairfax County, Virginia: U.S. Geological Survey
Miscellaneous Field Studies Map MF-2047, scale 1:48,000.
IV-38 Reprinted from USGS Open-FUe Report 93-292-C
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Pennsylvania Geological Survey, 1978, Uranium near Oley, Berks County: Pennsylvania
Geology, v. 9, p. 29-31. .
Pennsylvania Topographic and Geological Survey, 1981, Glacial deposits of Pennsylvania:
Pennsylvania Topographic and Geological Survey, 4th ser., Map 59, scale 1:2,000,000.
Pennsylvania Topographic and Geologic Survey, 1984, Limestone and dolomite distribution in
Pennsylvania: Pennsylvania Topographic and Geologic Survey, 4th ser., Map 15, scale
approx. 1:2,000,000.
Pennsylvania Topographic and Geological Survey, 1985, Map of the Reading Prong, eastern
Pennsylvania, showing the locations of generalized gamma-ray anomalies detected by
carborne survey, Pennsylvania Topographic and Geological Survey, 4th ser scale
1:50,000, 2 sheets.
Pennsylvania Topographic and Geologic Survey, 1990, Geologic map of Pennsylvania:
Pennsylvania Topographic and Geologic Survey, Map 7, scale 1:2,000,000.
Reimer, G.M., and Gundersen, L.C.S., 1989, A direct correlation among indoor radon, soil gas
radon and geology in the Reading Prong near Boyertown, Pennsylvania: Health Physics
v. 57, p. 155-160.
Richmond, G.M., and Fullerton, D.S., compilers, 1991, Quaternary geologic map of the Lake
Erie 4°x6° quadrangle, United States and Canada: U.S. Geological Survey Miscellaneous
Investigations Map 1-1420 (NK-17), scale 1:1,000,000.
Richmond, G.M., and Fullerton, D.S., compilers, 1992, Quaternary geologic map of the Hudson
River 4°x6° quadrangle, United States and Canada: U.S. Geological Survey Miscellaneous
Investigations Map 1-1420 (NK-18), scale 1:1,000,000.
Rose, A.W., and Korner, L.A., 1979, Radon in natural waters as a guide to uranium deposits in
Pennsylvania, in J.R. Watterson and P.K. Theobald (eds.), Proceedings of Seventh
international geochemical exploration symposium, Golden, Colo., April 17-19 1978
p. 65-75.
Rose, A.W., and Washington, J.W., 1989, Controls of seasonal variability in Rn content of soil
gas: Geological Society of America, Abstracts with Programs, v. 21, p. 63.
Rose, A.W., 1978, Geochemical exploration for uranium in Pennsylvania: Earth Mineral Science
v. 47, p. 49-52.
Rose, A.W., Washington, J.W., and Greeman, D.J., 1988, Variability of radon with depth and
season in a central Pennsylvania soil developed on limestone: Northeastern Environmental
Science, v. 7, p. 35-39.
Rumbaugh, J.O., HI, 1983, Effect of fracture permeability on radon-222 concentration in ground
water of the Reading Prong, Pennsylvania: Master's thesis, Pennsylvania State University,
University Park, PA, 111 p.
IV-39 Reprinted from USGS Open-Ftte Report 93-292-C
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Rumbaugh, J.O., HI, and Parizek, RJL, 1983, Effect of fracture permeability on radon-222
concentration in ground water of the Reading Prong, Pennsylvania: Geological Society of
America, Abstracts with Programs, v. 15, p. 675.
Rumbaugh, J.O., HI, 1987, Effect of aquifer transmissivity on radon-222 concentration in
groundwatcr of the Reading Prong, Pennsylvania: Geological Society of America,
Abstracts with Programs, v. 19, p. 127.
Sachs, H.M., Hernandez, TJL., and Ring, J.W., 1982, Regional geology and radon variability in
buildings: Environment International, v. 8, p. 97-103.
Schmicrmund R.L., 1977, Geology and geochemistry of uranium deposits near Penn Haven
Junction, Carbon County, Pennsylvania: Master's thesis, Pennsylvania State Univ.,
University Park, PA.
Schultz, A.P., and Wiggs, C.R., 1989, Preliminary results of a radon study across the Great
Valley of West Virginia: Geological Society of America, Abstracts with Programs, v. 21,
no. 2, p. 65.
Schultz, A.P., Wiggs, C.R., and Brower, S.D., 1992, Geologic and environmental implications
of high soil-gas radon concentrations in the Great Valley, Jefferson and Berkeley Counties,
West Virginia, in Gates, A.E., and Gundersen, L.C.S., eds, Geologic controls on radon:
Geological Society of America Special Paper 271, p. 29-44.
Senior, L.A., and Cecil, L.D., 1988, Elevated concentrations of Ra-226 and Ra-228 hi ground
water of the Chickies Formation, a Cambrian quartzite and basal conglomerate,
southeastern Pennsylvania: Geological Society of America, Abstracts with Programs,
v. 20, p. 69.
Sevon, W.D., Rose, A.W., Smith, R.C., H, and Hoff, D.T., 1978, Uranium in Caron,
Lycoming, Sullivan, and Columbia Counties, Pennsylvania: Guidebook for the 43rd
Annual Field Conference of Pennsylvania Geologists, Pennsylvania Topographic and
Geologic Survey, Harrisburg, 99 p.
Smith, A.T., 1980, Stratigraphic and sedimentologic controls for copper and uranium in red-beds
of the upper Devonian QtsTHIl Formation in Pennsylvania: Master's thesis, Pennsylvania
State University, University Park, PA.
Smith, R.C., U, and Hoff, D.T., 1984, Geology and mineralogy of copper-uranium occurrences
in the Picture Rocks and Sonestown Quadrangles, Lycoming and Sullivan Counties,
Pennsylvania: Pennsylvania Topographic and Geological Survey, 4th sen, Mineral
Resource Report 80, 269 p.
Smith, R.C., H, Reilly, M.A., Rose, A.W., Barnes, J.H., and Berkheiser, S.W., 1987, Radon;
a profound case: Pennsylvania Geology, v. 18, p. 3-7.
IV-40 Reprinted from USGS Open-File Report 93-292-C
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Szabo, Z. and Zapecza, O.S., 1991, Geologic and geochemical factors controlling uranium,
radium-226, and radon-222 in ground water, Newark basin, New Jersey: in Gundersen,
L.C.S., and Wanty ILB., eds., Geologic and geochemical field studies of radon in rocks
soils, and water; U.S. Geological Survey Bulletin 1971, p. 243-265.
Turner-Peterson, C.E., 1980, Sedimentology and uranium mineralization in the Triassic-Jurassic
Newark Basin, Pennsylvania and New Jersey: in Turner-Peterson, CE., ed., Uranium in
sedimentary rocks, application of the fades concept to exploration: Society of Economic
Paleontologists and Mineralogists, Rocky Mountain Section, Short Course Notes
t>. 149-175. '
Turner-Peterson, CE., Olsen, P.E., and Nuccio, V.F., 1988, Modes of uranium occurrence in
the Newark basin, New Jersey and Pennsylvania, in Robinson, G.R., Jr., and Froelich
A.J., eds., Proceedings of the Second U.S. Geological Survey workshop on early
Mesozoic basins of the eastern United States: U.S. Geological Survey Circular 946
p. 120-124. '
van Assendelft, A.C.E., and Sachs, H.M., 1982, Soil and regional uranium as controlling factors
of indoor radon in eastern Pennsylvania: Princeton University, Center for Energy and
Environmental Studies Report 145,68 p.
Wanty, R.B., and Gundersen, L.C.S., 1987, Factors affecting radon concentrations in ground
water; evidence from sandstone and crystalline aquifers: Geological Society of America,
Abstracts with Programs, v. 19, p. 135.
Wanty, R.B., and Gundersen, L.C.S., 1988, Groundwater geochemistry and radon-222
distribution in two sites on the Reading Prong, eastern Pennsylvania, in M.A. Marikos and
R.H. Hansman, eds., Geologic causes of natural radionuclide anomalies: Proceedings of
GEORAD conference, St Louis, MO, April 21-22,1987, Missouri Department of Natural
Resources Special Publication 4, p. 147-156.
Washington, J.W., and Rose, A.W., 1990, Regional and temporal relations of radon in soil gas to
soil temperature and moisture: Geophysical Research Letters, v. 17, p. 829-832.
IV-41 Reprinted from USGS Open-File Report 93-292-C
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EPA's Map of Radon Zones
The USGS1 Geologic Radon Province Map is the technical foundation for EPA's Map
of Radon Zones. The Geologic Radon Province Map defines the radon potential for
approximately 360 geologic provinces. EPA has adapted this information to fit a county
boundary map in order to produce the Map of Radon Zones.
The Map of Radon Zones is based on the same range of predicted screening levels of
indoor radon as USGS' Geologic Radon Province Map. EPA defines the three zones as
follows: Zone One areas have an average predicted indoor radon screening potential greater
than 4 pCi/L. Zone Two areas are predicted to have an average indoor radon screening
potential between 2 pCi/L and 4 PCi/L. Zone Three areas are predicted to have an average
indoor radon screening potential less than 2 pCi/L.
Since the geologic province boundaries cross state and county boundaries a strict
translation of counties from the Geologic Radon Province Map to the Map of Radon Zones
was not possible. For counties that have variable radon potential (i.e., are located in two or
more provinces of different rankings), the counties were assigned to a zone based on the
predicted radon potential of the province in which most of its area lies. (See Part I for more
details.)
PENNSYLVANIA MAP OF RAnnxr /r^jpq
The Pennsylvania Map of Radon Zones and its supporting documentation (Part IV of
this report) have received extensive review by Pennsylvania geologists and radon program
experts. The map for Pennsylvania generally reflects current State knowledge about radon for
its counties. Some States have been able to conduct radon investigations in areas smaller than
geologic provinces and counties, so it is important to consult locally available data
The zone designations for York, Adams and Monroe counties do not strictly follow the
methodology for adapting the geologic provinces to county boundaries EPA and the
Pennsylvania Bureau of Radiation Protection have decided to designate these counties as Zone
1. Although a large portions of these counties have moderate radon potential areas
supplemental indoor radon data from these counties indicate significant proportions'of the
homes tested are above 4 pCi/L.
Although the information provided in Part IV of this report --the State chapter entitled
"Preliminary Geologic Radon Potential Assessment of Pennsylvania" - may appear to be
quite specific, it cannot be applied to determine the radon levels of a neighborhood housing
tract, individual house, etc. THE ONLY WAY TO DETERMINE IF A HOUSE* HAS
ELEVATED INDOOR RADON IS TO TEST. Contact the Region 3 EPA office or the
Pennsylvania radon program for information on testing and fixing homes. Telephone numbers
and addresses can be found in Part II of this report.
V-l
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