United States
Environmental Protection
Agency
Air and Radiation
(6604J)
402-R-93-052
September 1993
4>EPA EPA's Map of Radon Zones
NEW YORK
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EPA'S MAP OF RADON ZONES
NEW YORK
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 Macpnaughey, 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 Ottoii, 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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TABLE OF CONTENTS
I. OVERVIEW
II. THE USGS/EPA RADON POTENTIAL
ASSESSMENTS:INTRODUCTION
III. REGION 2 GEOLOGIC RADON POTENTIAL
SUMMARY
V. PRELIMINARY GEOLOGIC RADON POTENTIAL
ASSESSMENT OF NEW YORK
V. EPA'S MAP OF RADON ZONES - NEW YORK
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OVERVIEW
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 ^c^s 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. , : '. -
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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 m 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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Purpose 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.
Development 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 Rauon Zones by extrapolating from the
v province level to the county level so that all counties in the'.US. 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 Nebrask;
Lincoln Couh t y
Hiji Uodcrilt Low
Figure 4
NEBRASKA - EPA Map of Radon Zones
Lincoln County
Zeae 1 Zone 2 Zone 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' predipted 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.
Tn 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 pCi/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, BPA 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 thr,ee 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 USCS/EPA RADON POTENTIAL ASSESSMENTS: AN INTRODUCTION
-.' ' ' . .,' >' '•-.'• • . ' - ' •.•• ' .
. 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. 2661-2'671) 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 (hey cannot and should not be used to estimate or predict the
indoor radon concentrations pf 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 iiidividualhpmes or housing
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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 these reports for 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 (2"Rn) is produced from the radioactive decay of radium (::6Ra), which is, in turn,
a product of the decay of uranium (-JSU) (fig. 1). The half-life of :"Rn is 3.825 days. Other
isotopes of radon occur naturally, but, with the exception of thoron (2:nRn), 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 drier 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 airmoves 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 hjghly 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 = 10~9 meters), or about 2x10"(' inches—this-is known as alpha
recoil (Tanner, 1980). Moisture in the soil lessens the chance of a recoiling r/adon 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 bu.t 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 orderrof-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 oh the hillslope than the homes, it cools and settles, pushing radon-lad'en air from
lower in the cave or cavity system into structures on the hillslope (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 d'riving 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 cbld 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 upper
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. , .
-.'.'• • 1 • ' . ,
GEOLOGIC DATA -
The typeS and distribution of lithologic units and other geologic features iri 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-
bearing 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 cpntact metamorphosed rocks.
Rock typqs 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 coatin«« on rock and soil grains, and organic
materials in soils and sediments. Less common are uianium 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
MacGregor, 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).
MURE 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 (!MBi), 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 of 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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FllCilT LINE SPACING OF SURE .A ER I. A L . SURVEYS
2 'KM (1 MILE)
5 KM (3 HILES)
2 i 5 KH
10 KH. {6 MILES)
5 i 10 IK
NO DATA
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 NUKE 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 primarv flightline spacing
typically between 3 and 6 miles, less than 10 percent ofthe 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 soil's 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 smeetitic (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 soil's 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 198,6
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, 1,989), 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. . ,
'11-9 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 relief 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
' , 11-11 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
ARCHITECTURE TYPE
INCREASING RADON POTENTIAL ^
POINT VALUE
1
<2pCi/L
< 1.5 ppmeU
negative
low
mostly slab
2
2-4pCi/L
1.5 - 2.5 ppm eU
variable .
moderate
mixed
3
>4pCi/L
>2.5j)pmeU
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:
Radon potential category
LOW
MODERATE/VARIABLE
HIGH
Probable average screening
Point range indoor radon for area
3-8 points
9-11 points
12-17 points
<2pCi/L
2-4pCi/L
>4pCi/L
POSSIBLE RANGE OF POINTS = 3 to 17
TABLE 2. CONFIDENCE INDEX MATRIX
INCREASING CONFIDENCE
FACTOR
INDOOR RADON DATA
AERIAL RADIOACTIVITY
GEOLOGIC DATA
SOIL PERMEABILITY
POINT VALUE
1
sparse/no data
questionable/no data
questionable
questionable/no data
2 .
fair coverage/quality
glacial cover
variable
variable
' 3
good coverage/quality
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 QF POINTS = 4 to 12
n-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 lev-1 for an a-ea was greater than 4 pCi/L, the indoor
radon factor was assigned 3 RI points.
Aerial radioactivity data used in this report are from the equivalent uranium map of the
conterminous United States compiled from NURE aerial gamma-ray surveys (Dtival and
others, 1989). These data indicate the gamma radioactivity from approximately the upper 30
,cm of rock and soil, expressed in units of ppm equivalent uranium. An approximate average —
value of eU was determined visually for .each area and point values assigned based on
whether.the. overall eU for the area falls below 1.5 ppm (1 point), between 1.5 and 2.5 ppm
(2 points), or .greater than 2.5 ppm (3 points). ' ;
The geology factor is complex and actually incorporates many geologic characteristics. In
the matrix, "positive" and "negative" refer to the presence or absence .and distribution of rock
types known to have high uranium contents and to generate elevated radon in soils or indoors.
Examples of "positive" rock types include granites, black shales, phosphatic rocks, and other
rock, types described in the preceding "geologic data" section. Examples of "negative" rock
types include marine quartz sands and some clays.. The term "variable" indicates that the
geology within the region is variable or that the rock types in.,the area are known'or suspected
to generate elevated radon in some areas but not in others due to compositional differences,
climatic effects, localizeddistribution of uranium, or other factors. Geologic information
indicates not only how much uranium is present in the rocks and soils,but also gives,clues for
predicting general radon emanation and mobility characteristics through additional factors
such as structure (notably the presence of faults,or shears) and gepchemical characteristics
(for example, a phosphate-rich sandstone will likely contain more uranium than a sandstone
containing little or no phosphate because the phosphate forms chemical complexes with
uranium). "Negative", "variable", and "positive" geology were assigned 1, 2, and 3 points,-
respectively. / . ' '
In cases where additional reinforcing or contradictory geologic evidence is available,
Geologic Field Evidence (GFE) points were added to or subtracted from an area's score
(Table 1). Relevant geologic field studies are important to enhancing pur. understanding of
how geologic processes affect radon distribution. In some cases, geologic models and ,
supporting field data reinforced'an already strong (high or low) score; in others, they provided
important contradictory data. GFE points were applied for geologically-sound evidence that
supports the 'prediction (but which may contradict one, or more factors) on the basis of known
geologic field studies in the area'or in areas with geologic and climatic settings similar
enough that they could be applied with full confidence. For example, areas of the Dakotas,
Minnesota, and Iowa that "are covered with Wisconsin-age glacial deposits exhibit a low aerial
radiometric signature and score only one RI point in that category. However, data from
geologic'field studies in North Dakota and Minnesota (Schumann and others, 1991) suggest
that eU is a poor predictor of geologic radon potential in this area because, radionuclides have
' , 11-13 Reprinted from USGS Open-File Report 93-292
-------
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
suggested by the radiometric data. No GFE point* are awarded if there are no 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 readily 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 nohrandom- 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,fo'r 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 depositst (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 s'd 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 models1-' (3 points); a'high.
confidence could berheld 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 i 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.
II-1.6 Reprinted from USGS Open-File Report 93-292 ' •
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REFERENCES CITED
Akerblom, G., Anderson, P., and Clavensjo, B., 1984, Soil gas radon--A source for indoor radon
daughters: Radiation Protection Dosimetry, v. 7, p. 49-54.
Deffeyes, K.S., and MacGregor, I.D., 1980, World uranium resources: Scientific American,
v. 242, p. 66-76. ,
Durrance, E.M., 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 theapplication of geophysics to engineering and environmental problems
(S AGEEP), Golden, Colorado, March 13-16,1989:, Society of Engineering and Mineral
Exploration Geophysicists, p. 1-61. ,
Duval, J.S., Cook, B.G., 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, W.J., 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.
Duval, J.S., Reimer, G.M., Schumann, R.R., Owen, D.E., and Orion, J.K., 1990, Soil-gas .
radon compared to aerial and ground gamma-ray measurements at study sites near Greeley
and Fort Collins, Colorado: U1S. 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,
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Gammage, R.B., Wilson, D.L., Saultz, R.J., and Bauer, B.C., 1993, Subtereanean transport of
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(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 Residing 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.
II-17 Reprinted from USGS Open-File Report 93-292
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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.
Kovach, E.M., 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 Bell, 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, M.H., 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, D.E., 1991, Correlations of soil-gas
and indoor radon with geology in glacially derived soils of the northern Great Plains, in
Proceedings of the 1990 International Symposium on Radon and Radon Reduction
Technology, Volume 2, Symposium Oral Papers: U.S. Environmental Protection Agency
report EPA/600/9-9 l/026b, p. 6-23-6-36.
JI-18 Reprinted from USGS Open-File Report 93-292
-------
Schumann, R.R., Owen, D.E., and Asher-Bolinder, S., 1992, Effects of weather and son
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. . .
~ s
Sextro, R.G., Moed, B.A., Nazaroff, W.W., Revzan, KX., 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.
- " " ' ' " ' ' '' f
Sterling, R., Meixel, G., Shen, L., Labs, K!, and Bligh, T,, 1985, Assessment of the energy
savings potential of building foundations research: Oak Ridge, Terin., 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, HI., 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 HI, 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 Aflas 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-1K76). . , •
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 2i2Rn: Health Physics, v. 57, p. 891-896.
H-19 Reprinted from^SGS Open-File Report 93-292
-------
APPENDIX A
GEOLOGIC TIME SCALE
Subdivisions (and their symbols)
Eon or
Eonothem
Phsnerozoic2
Proterozoic
(E)
Archean
IA)
Era or
Erathem
*
Cenozoic
ICD
Mesozoic2
(Mj)
Paleozoic
(Pi)
MiOflU
EirtY
froi.fOIoic 1X1
LJ»
MiDdlf
tiny
Period, System,
Subperiod, Subsystem
Quaternary
(Q)
Neogene 2
Subperiod or
T^;,~f Subsystem (N)
m Paleogene
i ' " Suboeriod or
Subsystem (Pi)
Cretaceous
(K)
Jurassic
U)
Triassic
(Ti)
• Permian
(P)
Pennsylvanian
Carboniferous 'PJ
*} *»ft\
66 (63-66)
.
-240
290 (290-305)
360 (360-365)
410 (405-415)
435 (435-440)
500 (495-510)
-570 3
900
2500
3000
3400
3800?
1Hanoes reflect uncertainties of isotopic and biostratio.raphie »5» assignments. Age boundaries not closely bracketed by existing
data shown by^ Decay constants and isotopic ratios employed are cited in Steiger and Jager (1977). Designation m.y. used for an
* Modifiers '(tower, middle, upper or early, middle, late) when used with these hems are informal divisions of the larger unit; the
•first letter ol me modifier Is lowercase.
'Rocks older than 570 Ma also called 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 pCi/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 pCi/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 Alow, 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. ,
amphibolite A mafic metamorphic rock consisting mainly of pyroxenes and(pr) amphibole and
plagioclase.
H-21 Reprinted from USGS Open-File Report93-292
-------
argillite, argillaceous Terms referring to a rock derived from clay or shale, or any sedimentary
rock containing an appreciable amount of clay-size material, i.e., 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.
batholith 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 that 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 smaU
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. .
n-22 Remitted from USGS Open-File Report 93-292
-------
delta, deltaic Referring to alow, flat, 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
river at the point at which the river loses its ability to transport the sediment, commonly where a
river 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
(CaMg(COs)2), 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 Saidof 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
H-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
metamorphic.
intermontane 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 than 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.
PhylUte, schist, amphibplite, and gneiss are metamorphic rocks.
moraine A mound, ridge, or other distinct accumulation of unsorted, unbedded 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, i.e., minerals containing PO4.
H-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 geqmorphic history, and whose topography, or landforms differ
significantly from adjacent regions. ....'.:.
olacer deposit See heavy minerals
residual Formed by weathering of a material in place.
residuum Deposit of residual material.
- , ! ' s ..
rhydlite 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.
schist A strongly foliated crystalline rock, formed 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 short period of time, usually less than seven days. May indicate the potential for an indoor
radon problem but does not indicate annual exposure to radon.
,i • '• . ' -' . = •
sediment Deposits of rock and mineral particles or fragments originating from material that is
, transported by air, water or ice, or 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 (Uthification) 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 surf ace 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 UnconsoUdated 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 • • . -
11-25 Reprinted from USGS Open-FUe 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 unbedded 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.
i
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.
t
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
Offices
State
EPA Region
EPA Region!
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 S.treet
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, W.A 98101
(202)442-7660
Alabama...1. ...............4
Alaska 10
Arizona . 1... 9
Arkansas........... '...'...<. 6
California ,.... . 9
Colorado •• •• 8
Connecticut .-.., 1
Delaware 3
District of Columbia .'.....'...3
Florida ............ 4
Georgia... '. ....4
Hawaii .9
Idaho ->0
Illinois.. • 5
Indiana ..............5 •
Iowa..... .-7
Kansas .- 7
Kentucky... -4
Louisiana ..... 6
Maine ..' -1
Maryland .....3
Massachusetts..... ••! .
Michigan .'...... 5
, Minnesota... 5
Mississippi............ 4
Missouri .7
Montana...... ... • 8
Nebraska :..!
Nevada 9
New Hampshire 1
New Jersey , -2
New Mexico..... -6
New York.... ...........2
North Carolina...... 4
North Dakota '.. • .8
Ohio................ - 5
Oklahoma. — • 6
Oregon 10 ,
Pennsylvania.. .'. 3
Rhode Island. .......1
South Carolina 4
South Dakota. -.. 8
Tennessee 4
Texas ............6
Utah 8
Vermont ••••• 1
Virginia.... .••• 3
Washington..... 10
West Virginia —..3
Wisconsin .....5
Wyoming ....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 Charles 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) 255-4845
Arkansas Lee Gershner
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, Roqm 600
Sacramento, CA 94234-7320
(916) 324-2208
1-800-745-7236 in state
Colorado Linda 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 06106-4474
(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 Rpbert Davis
of Columbia DC Department of Consumer and
Regulatory Affairs
614 H Street NW
Room 1014
< Washington, DC 20001
(202)727-71068
Florida N. Michael GiUey
Office of Radiation Control
Department of Health and
Rehabilitative Services
1317 Winewood Boulevard
Tallahassee, EL 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, ffl 96813-2498
(808) 5864700
H-28
Reprinted from USGS Open-File Report 93-292
-------
Idaho
Illinois
Indiana
Iowa
Kansas
Kentucky
PatMcGavarn
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
Maine Bob Stilwell
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 Leon J. Rachuba
Radiological Health Program
Maryland Department of the
Environment
2500 Broening Highway
Baltimore, MD 21224
(410)631-3301
1-800-872-3666 In State
Massachusetts 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 Hendershdtt
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 LauraOalmann
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
-------
Mississippi 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
Missouri 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
Montana Adrian C.Howe
Occupational Health Bureau
Montana Department of Health and
Environmental Sciences
Cogswell Building A113
Helena, MT 59620
(406) 444-3671
Nebraska Joseph Milone
Division of Radiological Health
Nebraska Department of Health
301 Centennial Mall, South
P.O. Box 95007
Lincoln, NE 68509
(402)471-2168
1-800-334-9491 In State
Nevada 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 Arlen Jacobson
North Dakota Department of Health
1200 Missouri Avenue, Room 304
P.O. Box 5520
Bismarck, ND 58502-5520
(701)221-5188
Ohio Marcie Matthews
Radiological Health Program
Department of Health
1224 Kinnear Road - Suite 120
Columbus, OH 43212
(614) 644-2727
1-800-523-4439 in state
H-30 Reprinted from USGS Open-File Report 93-292
-------
Oklahoma Gene Smith
Radiation Protection Division
Oklahoma State Department of
Health
P.O. Box 53551
Oklahoma City, OK 73152
(405)271-5221
Oregon George Toombs
Department of Human Resources
Health Division
' 1400 SW 5th Avenue
Portland, OR 97201
(503) 731-4014
Pennsylvania 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
Puerto Rico David Saldana
Radiological Health Division
G.P.O. Call Box 70184 <
Rio Piedras, Puerto Rico 00936
(809)767-3563
Rhode Islandi EdmundArcand
Division of Occupational Health and
Radiation
Department of Health
205 Cannon Building.
Davis Street
Providence, RI02908
(401)277-2438
South Carolina
Bureau of Radiological Health
Department of Health and
Environmental Control
2600 Bull Street
Columbia, SC 29201
(803) 734-4631
1-800-768-0362
South Dakota Mike Pochop
Division of Environment Regulation
Department of Water and Natural
Resources
Joe Foss Building, Room 217
523 E.Capitol
Pierre, SD 57501-3181
(605)773-3351
Tennessee 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
Texas Gary Smith
Bureau of Radiation Control
Texas Department of Health
, 1100 West 49th Street
Austin, TX 78756-3189
(512) 834-6688 "
Utah John Hultquist
Bureau of Radiation Control
Utah State Department of Health
,288 North, 1460 West
P.O. Box 16690
Salt Lake City, UT 84116-0690
(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 n
in New York •
(212)264-4110
H-31 Reprinted from USGS Open-Pile 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 Beattie L. DeBord
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
IE-32 Reprinted from USGS Open-File Report 93-292
-------
STATE GEOLOGICAL SURVEYS
•. - May, 1993
Alabama Ernest A. Mancini
Geological Survey of Alabama
P.O. Box 0
420 Hackberry Lane
Tuscaloosa, AL 35486-9780
(205)349-2852
Alaska Thomas E. Smith
Alaska Division of Geological &
Geophysical Surveys
794 University Ave., Suite 200
Fairbanks, AK 99709-3645
(907)479-7147
Arizona ' Larry D. Fellows
Arizona Geological Survey
845 North Park Ave., Suite 100
Tucson, AZ 85719
(602)882^795
Arkansas 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
Colorado 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 197.16-7501
(302)831-2833
Florida Walter Schmidt
Florida Geological Survey
903 W. Tennessee S..
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
Idaho 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, IL 61820 ,
(217)333-4747 , .
Indiana Norman C. Hester
Indiana Geological Survey
611 North Walnut Grove
Bloomington, IN 47405
(812)855-9350
Iowa Donald L. Koch
Iowa Department of Natural Resources
Geological Survey Bureau
109 Trowbridge Hall
Iowa City, IA 52242-1319 ,
(319)335-1575
Kansas LeeC. 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
Maine 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.
St. 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 &
LandSurvey
111 Fairgrounds Road
P.O. Box 250
Rolla, MQ 65401
(314)368-2100
Montana Edward T. Ruppel
Montana Bureau of Mines & Geology
Montana College of Mineral Science
v,' 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 .
Nevada 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. Chapin
New Mexico Bureau of Mines &
Mineral Resources
Campus Station
Socorro.NM 87801
(505)835-5420
New York Robert H. Fakundiny
New York State Geological Survey
3136 Cultural Education Center
Empire State Plaza
Albany, NY 12230
(518)474-5816
H-34 Reprinted fromUSGS Open-File Report 93-292
-------
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
600EastBlvd.
Bismarck, ND 58505-0840
(701)224-4109 ..
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
Oregon Donald A. Hull'
1 DepL of Geology & Mineral Indust;
Suite 965
800 NE Oregon St. #28
Portland, OR 97232-2162
(503)731-4600,
Pennsylvania Donald M. Hoskins
Dept. of Environmental Resources
Bureau of Topographic & Geologic
Survey
P\O. Box 2357
Harrisburg, PA 17105-2357 ''
(717) 787-2169
Puerto Rico Ramdn M. Alonso
Puerto RiccfGeological Survey
' Division
Box5887
Puerta de Tierra Station
San Juan, P.R. 00906
(809)722-2526
Rhode Island J. Allan Cain -
Department of Geology
University of Rhode Island
315GreenHall
Kingston, RI02881
(401)792-2265
South Carolina Alan-Jon W. Zupan (Acting)
South Carolina Geologipal Survey
5 Geology Road
Columbia, SC 29210-9998
(803)737-9440
South Dakota C.M. Christensen (Acting)
South Dakota Geological Survey
Science Center
University of South Dakota
Vermillion, SD 57069-2390
(605)677-5227
Tennessee Edward T.Luther
Tennessee Division of Geology
' ' '. 13th Floor, L & C Tower
401 Church Street
NashviUe, TN 37243-0445
(615)532-1500
Texas 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
Charlottesville,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
-------
West Virginia Larry D. Woodfoik
West Virginia Geological and
Economic Survey
Mont Chateau Research Center
P.O. Box 879
Mprgantown, 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
11-36 Reprinted from USGS Open-File Report 93-292
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EPA REGION 2 GEOLOGIC RADON POTENTIAL SUMMARY
.•"•-. ' • .- '. ' - ! . ' *y '• • • ' ' • , '
Linda C.S. Gundersenand R. Randall Schumann
U.S. Geological Survey
EPA Region 2 includes the states of New Jersey and New York. 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 indoorradon 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 pCi/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 2 is given in the individual state chapters. The individual chapters describing the geology
and radon potential of the states in EPA Region 2, though much more detailed than this summary,
are still 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
likely will be found. ,
Figure 1 shows the geologic radon potential areas in Region 2, combined and summarized
from the individual state chapters in this booklet These areas are based on the major geologic
provinces in these states. Figure 2 shows average screening indoor radon levels by county. The
data for New York were compiled by the New York State Department of Health and data for New
Jersey were compiled by the New Jersey Department of Environmental Protection and Energy. .
Figure 3 is a generalized geologic radon potential map of EPA Region 2.
NEW-JERSEY:
The New Jersey Highlands have been ranked high in geologic radon potential. Screening
measurements pf indoor radon in this area averaged 8.6 pCi/L. Uranium, in rocks of the New
Jersey Highlands is well documented in the literature. Uraninite and other U-bearing minerals
form layers and disseminations in several kinds of host rocks, including intrusive granitic rocks,
magnetite deposits, pegmatites, marble, veins, faults, shear zones, and feldspathic
metasedimentary gneiss. Soil permeability is generally moderate to high with a few areas of low
permeability. Glacial deposits in the New Jersey Highlands are, for the most part, locally derived
and, in some areas, they enhance radon potential because of high permeability. In other.areas,
glacial deposits may blanket more uraniferous bedrock and effectively lower the radon potential.
The Valley arid Ridge Province has been divided into two sections for this assessment.
Silurian and Devonian rocks of the Valley and Ridge and the Green Pond outlier have been ranked
moderate in radon potential. The Silurian and Devpnian rocks are predominantly conglomerate,
sandstone, shale, and limestone that generally have low to mpderate equivalent uranium associated
with them. The shales and local uranium mineral accumulations in the sandstones are the most
likely source of radon problems. A few homes with indoor radon concentrations greater than
20 pGi/L were measured in the Silurian and Devonian rocks.
m-1 Reprinted from USGS Open-File Report 93-292-B
-------
Figure 1. Geologic radon potential areas of EPA Region 2. 1-St. Lawrence-Champlain
Lowlands; 2-High Peaks; 3-Northwest Lowlands; 4-Adirondacks; 5-Tug Hill Plateau;
6-Erie-Ontario Lowland; 7-Hudson-Mohawk Lowland; 8-Allegheny Plateau; 9-New England
Upland-Taconic Mountains; 10-Manhattan Prong; ll-Aflantic Coastal Plain; 12-Valley and Ridge;
13-New Jersey Highlands-Hudson Highlands; 14-Triassic Lowland (NY)/northern Piedmont
(NJ); 15-southern Piedmont; 16-Inner Coastal Plain; 17-Outer Coastal Plain.
-------
Screening Indoor Radon
Average Concentration (pCi/L)
0.0 to 1.9
2.0 to 4.0
4.1 to 9.9
10.0 to 14.8
Figure 2. Average screening indoor radon levels, by county, for EPA Region 2. Data are
primarily from 2-7 day charcoal canister tests. Data for New York were compiled by the New
York State Department of Health; data for New Jersey were compiled by the New Jersey
Department of Environmental Protection and Energy. Histograms in map legend show the number
of counties in each category.
-------
GEOLOGIC RADON POTENTIAL
I I LOW(<2pCi/L)
[551 MODERATE/VARIABLE (2-4 pCi/L)
• HIGH (>4 pCi/L)
Figure 3. Generalized map showing geologic radon potential of EPA Region 2. For more detail,
refer to the individual state geologic radon potential chapters.
-------
The Cambrian-Ordovician rocks of the Valley and Ridge have been ranked high in geologic
radon potential. The Hardyston Quartzite is known to have local uranium and uranium mineral
deposits, and the black shales and carbonate soils are also sources of indoor radon. Screening
measurements of indoor radon in the Valley and Ridge averaged 7.6 pCi/L. Equivalent uranium is
generally moderate to high over the Cambrian andOrdovician sedimentary rocks. Soil ;
permeability is generally moderate.
The northern and southern Piedmont provinces together form the Newark Basin. The
basin is underlain by Triassic sandstone, siltstones, and shales; Jurassic basalt and diabase; and
Jurassic siltstone, shales, and sandstones. Of all these rock types, the black shales have the
greatest potential to be a source of radon problems. Black shales are not as abundant in the '
northern Piedmont as in the southern Piedmont The average screening indoor radon level in the
northern Piedmont is 1.7 pCi/L; indoor radon levels greater than 4 pCi/L are probably associated
with the black shales of the lower Passaic Formation and uranium mineralization along the northern
border fault and in adjacent rocks. Sands' and conglomerates'of the upper Passaic Formation with
low geologic radon potential dominate the northwestern part of the northern Piedmont. Jurassic
basalts and interbedded sands and shales with low to moderate radon potential make up the western
half of the northern Piedmont Low to moderate radon potential is expected for the eastern half of
the northern Piedmont, which is underlain by sands interbedded with lacustrine shales of the
Passaic Formation and diabase of the Palisades sill that intrudes along the Lockatong Formation- .
Stockton Formation contact This thin layer of Lockatong Formation may be responsible for the
single indoor radon level greater than 20 pCi/L found near here. The northern Piedmont has been
ranked low in geologic radon potential overall. The southern Piedmont is underlain by the ;
uraniferous black shales and siltstones of the lower Passaic Formation, the uraniferous black
shale's of the Lockatong Formation, and the uraniferous black shales and locally uraniferous
sandstones of the Stockton Formation. Average indoor radon for the southern Piedmont is
4.9 pCi/L, Equivalent uranium is also moderate to high. Soil permeability is low to moderate.
The southern Piedmont has been ranked high in geologic radon potential. .
The Inner Coastal Plain Province, underlain by Cretaceous and Early Tertiary sediments, is
ranked moderate in radon potential. Screening measurements of indoor radon in the Inner Coastal
Plain averaged 2.4 pCi/L. Equivalent uranium is generally moderate. Soil permeability is
moderate to .high. Soil radon studies indicate that the glauconitic sediments are significant sources
of radon. The highest soil radon concentrations and radioactivity were found in the glauconitic
sands of the Cretaceous EnglishtOwn and Navesink Formations, the Mount Laurel Sand, and the
Tertiary Hornerstown Sand. ,
The Outer CoastaJL Plain has been ranked low in radon potential. Soil radon studies of the
Tertiary Kirkwood Formation, Cohansey Sand, and Pleistocene residuum indicate that they are
relatively poor sources of radon. Equivalent uranium is generally low. Soil permeability is
moderate to high and the average indoor radon for the province is low (1.4 pCi/L). .
NEW YORK . '
The Erie-Ontario Lowland and Tug Hill Plateau are underlain by a flat-lying sedimentary
sequence with abundant limestone, dolomite, shale, sandstone, and distinctive salt deposits.
Counties in the Erie-Ontario Lowland generally have indoor radon geometric means of less than
2 pCi/L and average indoor radon concentrations of less than 4 pCi/L. A veneer of impermeable
clay covers a significant portion of the Erie-Ontario Lowland and generates low to moderate indoor
m-5 Reprinted from USGS Open-File Report 93-292-B
-------
radon levels. Discrete occurrences of very coarse gravel and some marine shales may cause some
of the moderate and locally high radon levels found in the area. Although the Erie-Ontario
Lowlands have low radon source strength, low permeability, and consequently low radon
potential, radon potential is high in association with gravels in drumlins, outwash, moraines, till,
and beach ridges in the region. Significant accumulations of these coarse glacial deposits occur in
Wayne County and in the eastern portion of the province around the Tug Hill Plateau. We have
assigned an overall moderate/variable radon potential to the area based on the majority of county
indoor radon averages being greater than 2 pCi/L, the variably low to high radon source potential
of the underlying geology, variably low to high soil permeability, and low (<1.5 ppm elJ) to
moderate (1.5-2.5 ppm eU) radioactivity. ,
The Hudson-Mohawk Lowland is underlain by sandstone, siltstone, shale, and
conglomerate of variable ages. In this assessment, the lowland has been ranked generally
moderate or variable in radon potential, as the geology and glacial deposits of the area are highly
variable and radon potential varies likewise from low to high. Equivalent uranium is generally
moderate to locally high (>2.5 ppm eU)iin this area. Soils have moderate to locally high
permeability. The region is underlain predominantly by shale with average to below-average
radium concentrations and indoor radon over the shale is generally low. High levels of indoor and
soil radon are associated with gravelly kame and till deposits found above valley bottoms and with
gravel concentrations in sandy glacial deposits, generally moderate radon levels are associated with
lacustrine delta and kame deposits, and generally low levels are associated with Recent floddplain
deposits, lacustrine silt and clay, lacustrine sand, and dune sand.
The St. Lawrence and Champlain Lowlands are underlain by sedimentary rocks of
Cambrian through early Ordovician age with relatively low geologic radon potential. However,
some of the very coarse gravel deposits have moderate to high radon potential. Equivalent uranium
is generally low with a few moderate areas. Counties in the lowlands have indoor radon geometric
means less than 2 pCi/L and basement average concentrations of indoor radon less than 3 pCi/L. A
veneer of impermeable clay covers much of the area; however, areas of highly permeable, very
coarse glacial gravels and gravel in beach ridges may cause some of the moderate to high radon .
levels found in the area. Local occurrences of elevated (>4 pCi/L) indoor radon are associated with
gravels in drumlins, outwash, moraines, till, and beach ridges. Because of these highly permeable
deposits and county average radon greater than 2 pCi/L, these provinces have been ranked
moderate in radon potential.
The Allegheny Plateau is underlain by sedimentary rocks, predominantly shales,
limestones, and sandstones. Soils in the southern part of the plateau have low to moderate
permeability except for glacial gravel deposits, primarily in valleys, which have high permeability.
In the northern plateau, the soils have low permeability, with the exception of local glacial gravels.
The plateau has been ranked high in radon potential overall. However, parts of the Allegheny
Plateau are low to moderate in radon potential, especially areas in the Catskill Mountains.
Equivalent uranium is generally moderate in the plateau and is high along the south-central border
with Pennsylvania. The radioactivity pattern may correspond to the geometry of the Valley Heads
Moraine in the Finger Lakes region, with thinner till and progressively higher radioactivity south of
the moraines. The central and southern parts of the plateau have high radon potential in association
with coarse kame, till, and other gravel deposits which are generally restricted to valleys. Two
belts of uraniferous black shale, the Marcellus Shale and West Falls Group shales, cross central
and southern New York and cause significant high indoor radon from Onondaga County to Erie
County. Other black shales and related sedimentary rocks in the plateau do not appear to have as
ni-6 Reprinted from USGS Open-File Report 93-292-B
-------
high uranium contents. Elevated indoor radon concentrations near the contact between the
Onondaga limestone and the Marcellus Shale may be due to remobilization of uranium from the
shale into the fractured limestone. Of the northern counties in the Allegheny Plateau, only Seneca
County has an indoor radon average less than 4 pCi/L and it is considered to have moderate radon
potential. The northern, more populous portion of Seneca County is underlain by glacial clays and
the rest of the county is covered by till. Gravelly -glacial deposits are the cause of most of the high
radon found in the southern plateau, probably due to high permeability and high radon emanation ,
coefficients. Because the alluvial valley and moraine deposits are discrete bodies, categorizing
whole counties as high in radon potential may not be accurate. In addition, many towns are built in
the valleys, on the deposits most likely to cause high radon, and most of the indoor radon data
available for the counties is from these towns. Further work is needed outside of the towns located
in the valleys to accurately evaluate the uplands and counties as a whole. Because many of the
uplands are underlain by highly fractured shales, there is a geologic potential for elevated indoor
radon Most counties in the Allegheny Plateau have indoor radon geometric means in the 2-4
pCi/L range and county averages greater than 4 pCi/L. Four counties-Allegany, Chemung,
Cortland, and Steuban-have county indoor radon averages greater than 10 pCi/L. Sullivan
County, which is mostly located inthe Catskill Mountains, has lower indoor radon than
surrounding counties with an average of 3.1 pCi/L and geometric mean of 1.7 pCi/L. This county
is considered to be moderate in radon potential.
The Hudson Highlands, which are the northeastern extension of the Reading Prong, have
• been ranked high in radon potential, but the radon potential is actually highly variable. These
mountains consist of a wide variety rock types, Equivalent uranium is generally moderate, with
local lows and highs. Soils are thin and stony with locally thick accumulations of low-permeability
till. Numerous uranium localities and associated gamma-radioactivity anomalies are well
documented in the Hudson Highlands. These uranium deposits appear to be the cause for localized
occurrences of very high indoor radon levels. Faults and shear zones in the Highlands also host
uranium mineralization and are well known throughout the Appalachians for causing high indoor
radon levels. Faults may also be an important radon source iri parts of the Adirondacks and New
England Upland. Rocktypes which tend to be low in uranium in the Hudson Highlands include
amphibolitic gneisses, quartz-poor gneisses, and some marbles. Because the composition and
location of very high uranium concentrations in these rocks is so variable, indoor radon is highly
variable. The Hudson Highlands underlie parts of Putnam and Orange Counties, which have
county indoor radon geometric means of 2.4 and 2.8 pCi/L respectively, and county indoor radon
averages greater than 4 pCi/L. The Hudson Highlands are high in radon potential because of the
very high indoor radon levels found in some homes, because many of the homes are builtinto l
bedrock, and because high levels of radon in well-water also occur.
The Manhattan Prong is made up of metamorphic and igneous rocks with generally low
amounts of uranium and low radon potential. No direct correlation between any of the Manhattan
Prong rocks and indoor radon has been made. Equivalent uranium is generally low to moderate.
Soils have low to moderate permeability. Counties underlain by the Manhattan Prong (Westchester
County and most of New York City) have indoor radon geometric means < 1.5 pCi/L and average
indoor radon < 2.4 pCi/L.
, ', The New England Upland-Taconic Mountains area is underlain predominantly by slate,
phyllite, graywacke, and limestone. This area has been ranked high in radon potential. The
county geometric means for indoor radon in this province are greater than 2 pCi/L and the county
averages are greater than 4 pCi/L. Equivalent uranium is moderate to locally high. Soil
ffl-7 Reprinted from USGS Open-File Report 93-292-B
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permeability is low to moderate, with locally high permeability in glacial gravels. High indoor
radon levels appear to be related to highly permeable glacial and fluvial sediments along the
valleys.
The High Peaks and most of the central Adirondacks are made up of anorthosite and
gneiss, both of which are low in uranium and unlikely to cause radon problems. The rim of the
Adirondacks is composed predominantly of metasedimentary and metavolcanic rocks, several of
which contain local uranium occurrences and have locally high radon potential. Equivalent
uranium in the Adirondacks is low over the High Peaks and surrounding charnockitic rocks.
Moderate and locally high equivalent uranium is associated with the Northwest Lowlands and
scattered areas in metasedimentary rocks and iron deposits in the southeastern and eastern rim of
the Adirondacks. Soils have low to moderate permeability with locally high permeability in sandy
and gravelly glacial deposits. Most counties in the Adirondack Mountains have geometric means
of indoor radon less than 2 pCi/L. Average indoor radon is < 1.5 pCi/L in Essex, Hamilton, and
Franklin Counties, but greater than 2 pCi/L for Herkimer, Warren, St. Lawrence, and Lewis
Counties. These counties also lie partially in other geologic provinces.' We rank the High Peaks
and Adirondacks low in radon potential but rank the Northwest Lowlands moderate in radon
potential due to the high radioactivity, local occurrence of uranium, local glacial gravel deposits,
the sheared and faulted metamorphic rocks, and higher indoor radon in St. Lawrence County.
In the Valley and Ridge section, sedimentary rocks of Cambrian through Ordbvician age
comprise the underlying bedrock and have been ranked high in radon potential but may be locally
low to moderate. Cambrian and Ordovician rocks consist of a marine shelf sequence with.basal
Cambrian sandstones and conglomerates followed by a highly variable sequence of interbedded
shales and carbonate rocks. Many of the black shales in this sequence are elevated in uranium (>2
ppm) and, although the limestones are relatively low in uranium, the local residual soils formed on
limestones in the valleys of the area may be elevated in uranium. Indoor radon is elevated
(> 4 pCi/L) in basements of homes built on limestone soils of the Wallkill Valley, on black shale
bedrock, and especially in glacial gravel deposits containing black shale.
The Triassic Lowland is underlain by fluvial quartz sands, minor siltstones and shales, and
Jurassic basalt and diabase, and underlies most of Rockland County. Of these rock types, the
shales have the potential to be a source of radon problems; however, they are not abundant. Black
shales and gray sandstones in the lower Passaic Formation are similar to uranium-bearing units in
the same formation in New Jersey, but they make up a minor part of the section. Rockland County
has a basement indoor radon average of 2.2 pCi/L and a geometric mean of 1.3 pCi/L. Equivalent
uranium is low to moderate for the Triassic Lowlands. Soil permeability is generally low to
moderate. The Triassic Lowlands have been ranked low in radon potential.
Long Island, in the Atlantic Coastal Plain Province, is made up of glacial deposits and
marine sediments containing little or no uranium. Indoor radon measurements are among the
lowest in the State. Counties of the Atlantic Coastal Plain have indoor radon geometric means less
than 2 pCi/L and average concentrations of indoor radon less than 2 pCi/L. Permeability is
moderate to high with local areas of low permeability. A number of boulders in the glacial
moraines on Long Island have high levels of radioactivity and coarse gravels and sands of the
glacial outwash may also have isolated uranium concentrations, making them local sources of
elevated radon.
ffl-8 Reprinted from USGS Open-File Report 93-292-B
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PRELIMINARYGEOLOGIC RADONPOTENTIAL ASSESSMENT OF NEW YORK
by Linda C.S. Gundersen andR. Randall Schumann
U.S. Geological Survey . i
.INTRODUCTION ,
The State of New York has been conducting radon studies since the late 1970s. Since
1985, the State has had a diverse radon program including information and outreach, radon testing,
training for contractors in radon mitigation and detection, and technical and financial assistance
(Laymon and others, 1990). As part of their testing program, New York State now has a database
.of over 50,000 random and non-random charcoal canister indoor radon measurements. These data
indicate that several areas of New York have the potential for elevated indoor radon levels.
Examination of these data in the context of geolbgy, soil parameters, and aerial radioactivity
suggest that certain surficial deposits and rocks of the Allegheny Plateau, Hudson Highlands,
Taconic Mountains, and YalleySand Ridge have the potential to produce elevated levels of indoor
radon (> 4 pCi/L). Surficial deposits and rocks of the Hudson-Mohawk Lowland, Erie-Ontario
Lowlands, the Champlain and St. Lawrence Lowlands, and the Northwest Lowlands of the
Adirondacks are generally more moderate in radon potential but may be locally high where glacial
deposits are highly permeable. Surficial deposits and rocks of the Adirondacks, the Triassic
Lowlands, Manhattan Prong, and the Atlantic Coastal Plain are relatively low in radon potential.
This is a generalized assessment of geologic radon potential of rocks, soils, and surficial
deposits of New York. 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 homeis 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 New York (fig. 1) is in part a reflection of the underlying bedrock .
geology (fig. 2) and the extensive glaciation of the State. Several of the provinces shown in
figure 1 have been slightly modified from the classically defined physiographic provinces by using
geologic boundaries in order to make better 'geologic sense for this radon potential assessment
The St. Lawrence and Champlain Lowlands are in the most northerly region of New York and
grade from a nearly level marine plain in the east to gently rolling hills with relief of approximately
100 feet in the west. The lowlands are underlain by Cambrian and Ordovician sandstone,
dolomite, and limestone. The Adirondack Highlands include the highest mountains in the State,
especially in the High Peaks region, which is underlain by resistant anorthosite rock. Mt. Marcy is
the highest peak, at over 5000 feet in elevation above sea level. Average relief in the Adirondack
Highlands is 1000-2000. feet. The Northwest Lowlands are an area of lowlands in the
northwestern part of the Adirondacks that are underlain by metamorphosed sedimentary rocks.
IV-1 Reprinted from USGS Open-File Report 93-292-B
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NY GEOLOGIC MAP EXPLANATION-1
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EXPLANATION
GENERALIZED GEOLOGIC MAP OF NEW YORK
ATLANTIC COASTAL PLAIN
Quaternary Till, gravel, sand, and mud; Recent marine deposits-sand, mud, and clay;
small outcrops of Cretaceous Monmouth and Raritan Formations-sand and mud
TRIASSIC LOWLAND
TRIASSIC-JURASSIC
Newark Supergroup-arkose, mudstone, and siltstone
Conglomerate facies of Newark Supergroup (Hammer Creek Formation)
Palisades Diabase
ALLEGHENY PLATEAU .
DEVONIAN
Conewango Group-shale, siltstone, and sandstone in the west, grades to shale,
sandstone, and conglomerate to the east; Coneaut Group-shale and siltstone in the west,
replaced by shale and sandstone to the east; includes isolated outcrops of the Pennsylvanian
Pottsville and Mississippian Pocono Groups (shale, sandstone, and conglomerate)
along the Pennsylvania border
»
Canadaway Group—interbedded shales and siltstones with some sandstone
Java Group-shale and sandstone; West Falls Group-shale, sandstone, and siltstone
Sonyea Group-shale; Genesee Group-shale, sandstone, and limestone in the west,
grades to shale, sandstone, and siltstone to east; Tully Limestone
Hamilton Group-shale, sandstone, siltstone, and limestone
inn Onadaga Formation-limestone; Tristates Group-limestone, sandstone, and shale;
Ml Helderberg Group-limestone and dolostone
SILURIAN
Rondout Formation, Binnewater Sandstone, High Falls Shale, Warwarsing,
Decker,.and Bossardville Limestones, Poxono Island Formation-dolostone,
limestone, shale, and sandstone
Bloomsburg, Guymard, and Shawangunk Formations and Otisville Shale-
quartzite, shale, sandstone, and conglomerate
ERIE-ONTARIO LOWLAND
SILURIAN
Salina Group-dolostone, limestone, shale, gypsum, salt
. .„ Lockport Group-dolostone and limestone
A&*?
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NY GEOUCX3ICMAPEXPLANA.TlON-i
Clinton Group-shale, sandstone, limestone, dolostone, hematite
Medina Group-sandstone, shale
ORDOVICIAN
Queenston Formation-shale, siltstorie
Oswego Sandstone
Lorraine Group-sandstone, siltstone, and shale
Trenton and Black River Groups-limestone, dolostone, shale, and chert
ST. LAWRENCE IjOWLAND
ORDOVICIAN
Trenton, Black River, and Chazy Groups-limestone, dolostonei shale, and chert
CAMBRIAN-ORDOVICIAN
Beekmantown Group and Theresa Formation-limestone, dolostone arid sandstone
CAMBRIAN
Potsdam Sandstone-quartz sandstone and conglomerate
HUDSON-MOHAWK LOWLAND
ORDOVICIAN
Austin Glen, Mount Merino, and Indian River Formations-graywacke, shale,
slate, and chert
Schenectady Formation-graywacke, sandstone, siltstone, and shale
Utica and Snake Hill Formations-black shale and siltstone
CAMBRIAN-ORDOVICIAN
Beekmantown Group and Theresa Formation-limestone, dolostone, and sandstone
CAMBRIAN '
Potsdam Sandstone-quartz sandstone and conglomerate
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NY GEOLOGIC MAP EXPLANATION - 3
NEW ENGLAND UPLAND AND VALLEY AND RIDGE
DEVONIAN
Hamilton Group-shale, sandstone, and conglomerate
SILURIAN-DEVONIAN
Green Pond Conglomerate, Longwood Shale, Poxono Island Formation,
Decker Limestone, Helderberg and Tristates Groups-limestone, shale, dolomite,
sandstone, and conglomerate
ORDOVICIAN ,
Waloomsac, Snake Hill, and Balmville Formations- black shale and slate,
graywacke and metagraywacke, melange, limestone, and limestone conglomerate
Austin Glen, Mount Merino, and Indian River Formations (Livingston thrust
slice)-graywacke, shale, slate, chert; includes pillow lava at Stark's Knob, Saratoga
County
CAMBRIAN-ORDOVICIAN
Stockbridge and Wappinger Groups-limestone, dolostone, sandstone, siltstone,
shale, and quartzite
Nassau, Hatch Hill, Deep Kill, Mount Merino, Indian River Formations
(Giddings Brook thrust slice>-slate, shale, quartzite; includes limestone, dolomite, chert,
conglomerate, and graywacke
CAMBRIAN
Everett Schist (Everett thrust slice)-schist with minor metagraywacke lenses
Bomoseen and Nassau Formations (Chatham thrust slice)-black shale and quartzite
Bomoseen and Nassau Formations (Dorset Mountain thrust slice)-slate with
graywacke sandstone, and quartzite
Rensselaer Graywacke (Rensselaer thrust slice)-graywacke and shale
Austerlitz Phyllite (Berlin thrust slice)-phyllite with minor quartzite
PROTEROZOIC
Calcitc and dolmitic marble, calcsilicate rock, interlayered gneisses
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NY GEOLOGIC MAP EXPLANATION-4
7-.X
MANHATTAN PRONG
ORDOVICIAN
Cortiandt mafic complex-diorite with hornblende, hornblende norite, hornblendite,
pyroxenite, and minor amounts of other mafic rocks
Bedford Gneiss-biotite-quartz-plagioclase gneiss and interlayered amphibolite
Harrison Gneiss-biotite-hornblende-quartz-plagioclase gneiss
Staten Island Serpentinite
1 '- '
CAMBRIAN-ORDOVICIAN
Hartland Formation-amphibolite and pelitic schist
Inwood Marble and Lowerre Quartzite
CAMBRIAN
Manhattan Formation-pelitic schist and amphibolite
PROTEROZOIC
Yonkers, Pound Ridge, and Fordham Gneisses-granite gneiss, hornblende
gneiss, biotite gneiss, and amphibolite
HUDSON HIGHLANDS
PROTEROZOIC
Leucocratic gneiss ,
Calcitic and dolomitic marble, calcsilicate rock, and interlayered gneisses
Pyroxene-hornblende granitic gneiss (charnockite)
Biotite granitic gneiss and hornblende granitic'gneiss
Interlayered hornblende granitic gneiss and amphibolite
Hornblende granitic gneiss , .
Biotite-quartz-plagioclase gneiss with subordinate biotite granitic gneiss, amphibolite, and
, calcsilicate rock .
Biotite-quartz-feldspar gneiss with garnet, sillimanite, cordierite, graphite, sulfides, and
minor marble and calcsilicate rock
'< '.•'•' -• ' • •
Garnet-quartz-feldspar gneiss with minor marble, amphibolite, and rusty gneiss
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NY GEOLOGIC MAP EXPLANATION - 5
».•*.
ADIRONDACKS
PROTEROZOIC
Biotite and/or hornblende granitic gneiss, biotite-quartz-plagioclase gneiss, other
metasedimentary rocks, ampWboHte, migmatite
I Leucocratic gneiss
Metasedimentary rocks-dominantly calcitic and dplomitic marble, calcsilicate rock,
quartzite, and interlayered gneisses
Mangerite or charnockite with plagioclase crystals from anorthosite
Interlayered hornblende granitic gneiss and amphibolite
Hornblende syenitic gneiss (mangerite)
Metagabbro and amphibolite
Olivine-bearing granitic gneiss
Metanorthosite and anorthositic gneiss
Biotite-quartz-plagioclase gneiss and migmatite, may contain garnet
Tonalitic gneiss
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Southwest of the Adirondacks lies the Tug Hill Plateau, an isolated upland in the Erie-Ontario
Lowlands. Elevation varies from 1000 to 2000 feet and relief is low. The Tug Hill Plateau is
underlain mostly by Ordovician quartzite. The Erie-Ontario Lowland lies south of Lake Erie and
Lake Ontario and has a maximum elevation of 1500 feet. Th
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Erie Ontario Lowland and Hudson-Mohawk Lowland Provinces
Most of the Erie-Ontario Lowland and the Hudson-Mohawk Lowland are underlain by
sandstone, shale, and limestone. These rocks crop out in east-west trending belts across the State
to the Hudson-Mohawk Lowland, where the rocks underlie irregular northeast-trending areas
disrupted by faults. The eastern part of the Erie-Ontario Lowland comprises a broad syncline of
sandstone and shale that plunges to the southwest and forms the Tug Hill Plateau.
Sandstone and conglomerate of the Cambrian Potsdam Formation underlie small areas along
• the contact with Proterozoic rocks of the Adirondacks. The Potsdam is overlain by narrow,
discontinuous belts of dolomite, sandstone, and shale of the Theresa Formation. Limestone and
dolomite of the Cambrian-Ordovician Beekmantown Group and the Ordovician Black River and
Trenton Groups overlie the Theresa Formation where present, and unconformably overlie rocks of
the Adirondacks elsewhere.. The Beekmantown Group is restricted to a belt of outcrops along the
northern and western edge of the Hudson-Mohawk Lowland, whereas the Black River and
" Trenton Groups are most prominent in the eastern and northern portion of the Erie-Ontario
Lowland. The basal unit of the Black River Group also contains interbedded shale and arkosic
sandstone and the uppermost unit of the Trenton Group contains black shales intercalated with the
limestone.
The Ordovician carbonate rocks just described are overlain by Ordovician black and gray
shale and siltstone. In the Erie-Ontario Lowland, the shales and siltstones are represented by the
Lorraine Group, and are equivalent to black shale and siltstone of the Snake Hill Formation that
underlies about two-thirds of the Hudson-Mohawk Lowland. The Snake Hill is overlain by
graywacke and sandstone interbedded with gray to black siltstone and shale of the Schenectady
Formation, which underlies a large area in the western part of the Hudson-Mohawk Lowland. The
Lorraine Group in the Erie-Ontario Lowland is overlain by marine sandstone, siltstone, and shale
of the Ordovician Oswego Sandstone. The top of the Ordovician is the Queenstbn Formation,
consisting of red siltstone, shale, and minor sandstone.
Silurian rocks unconformably overlie the Ordovician rocks and comprise much of the
western part of the Erie-Ontario Lowland. At their base, the Silurian.rocks are sandstone,
siltstone, and shale of the Medina Group, overlain by shale and carbonates of the Clinton Group,
then carbonates of the Lockport Group, and finally, gypsiferous shale and carbonates of the Salina
Group. The Silurian rocks progressively onlap onto the Ordovician rocks to the east.
Allegheny Plateau Province - .
The Allegheny Plateau is underlain predominantly by marine to fluvial Devonian shales,
sandstones, and minor limestones forming broad east-west trending belts that narrow to the east.
In general, each stratigraphic unit is coarser grained in the east, grading into finer, shaly rocks to
the west. The oldest rocks of this province are in the southeast where Silurian clastic rocks
comprise a narrow belt forming the Shawangunk Mountains. These rocks include quartz-pebble
conglomerate and sandstone of the Shawangunk Formation overlain by the Otisville Shale,
Guymard Quartzite; and red shale and sandstone of the Bloomsburg Formation. These are
overlain by a narrow band of Silurian dolomite, limestone, and shale.
The Devonian Helderberg Group, Ulster Group, and the Onondaga Limestone form a narrow
belt along most of the northern and eastern margins of the Allegheny Plateau. The Helderberg
Group is dolomite and fossiliferous limestone, becoming shaly at the top of the unit. The
Helderberg is conformably overlain by gray to black shaly limestone, limestone, shale, and
siltstone of the Ulster Group. To the west, quartz sandstone of the Oriskany Sandstone
IV-12 Reprinted from USGS Open-File Report 93-292-B
-------
unconformably ovedies progressively older rocks of the Helderberg Group. The fossiliferous
Onondaga Limestone conformably overlies the Ulster Group and unconformably overlies the
Oriskany Sandstone and the sandy, siltyBois Blanc Limestone in the west,
. The Onondaga Limestone is conformably overlain by the Devonian Hamilton Group, which
forms a prominent belt parallel to the limestones. The Hamilton Groupls dominated by black
shales (including the Marcellus, Skaneateles, Ludlowville, Panther Mountain, and Moscow
Formations). Limestone interbeds become numerous upsection and to the west and the shales also
grade upward'and eastward into shale, siltstone, and sandstone. Conglomerate and.sandstone of
the Skiinnemunk Formation occur in the southeasternmqst exposures of the Hamilton Group.
In the Finger Lakes region, the Hamilton Group is unconformably overlain by a. verythin,
discontinuous belt" of Tully Limestone. In the east, the Hamilton Group is conformably overlain
by deltaic and marine shale, siltstone, and sandstone of the Devonian Genesee and Sonyea Groups
which unconformably overlie the'Hamilton Group and Tully Limestone to the west. These rock
units form a broad belt comprising nearly a quarter of the area of the province. The Genesee
Group is more sandstone rich to the east and upsection and is more limestone rich and shaly near
the base and to the west The Sonyea Group is also more sandstone and siltstone rich to the east
and contains more black shale to the west. /
The Devonian West Falls Group and the overlying Java Group form a broad belt in the
southeastern margin of the province that thins to the west. The West Falls Group in the east is
, dominated by fluvial sandstone, siltstone,,and conglomerate. To the west these rocks grade into
marine sandstone, siltstone, and shale: In the westernmost outcrops, the West Falls Group is
dominated by black shale. The easternmost Java Group consists of marine sandstone, siltstone,,
and shale and to the west it consists of marine black shale and gray siltstone. The Devonian
Canadaway Group comprises a broad belt of outcrop that narrows to the west where it forms a thin;
band along the border of Lake Erie. In the east, the Canadaway is interbedded marine sandstone,
siltstone, and shale. In the west, the Canadaway is black shale and siltstone.
The Devonian Conneaut and Conewango Groups comprises broad belt restricted to the
southwestern corner of the province. The Conneaut is composed of marine shelf sandstone,
siltstone, and shale in the east and interbedded gray siltstone and shale in the west. The
Conewango Group is also composed of marine shelf sandstone, siltstone, shale, and conglomerate
to the east and siltstone and shale to the west. The Mississippian Pocono Group overlies the
Conewango Group and is overlain by the Pennsylvanian PottsyUle Group. These Mississippian
and Pennsylvanian rOcks underlie a few small areas in the southwestern part of the province. The
Pocono Group is largely represented by fossiliferous marine sandstone and shale of the Knapp
Formation. The.Pottsville Group is represented by quartz-pebble conglomerate of the Olean
Conglomerate.
St Lawrence Lowlands Province .
The St. Lawrence Lowlands are underlain by Cambrian sandstone and Cambrian-Ordovician
carbonates that form broad northeast-trending belts. These rocks unconformably overlie the
Adirondack province rocks and also crop outin small, fault-bounded areas along the Lake
Champlain shore.
The oldest rocks of this province are Cambrian quartz sandstone and quartz-pebble
conglomerate of the Potsdam Formation. The Potsdam occurs discorttinuously along the boundary
with the Adirondacks and forms a broad band in the eastern part of the lowlands. The Potsdam is
overlain by a thick sequence of dolomite and limestone which includes the Cambrian Theresa
'.'-,', "" ", • . \
IV-13 Reprinted from USGS Open-File Report 93-292-B
-------
Formation and the Ordovician Beekmantown Group. The Theresa Formation consists of dolomite
and sandstone, whereas the Beekmantown Group is predominantly limestone and dolomite. These
rocks form a broad belt along the northern part of the lowlands and underlie several.small areas
along the Lake Champlain shore. The Beekmantown Group is uncpnformably overlain by
limestone of the Ordovician Chazy Group, which is unconformably overlain by limestone and
dolomite of the Ordovician Black River and Trenton Groups. These rocks underlie only a few
small areas along the shore of Lake Champlain. ' °
Valley and Ridge Province
The Valley and Ridge, as defined in this report, is underlain by marine black and gray shale,
siltstone, and sandstone, with minor carbonates and metamorphic rocks. These rocks are
complexly folded and faulted into a series of northeast-trending belts. Proterozoic rocks underlie
two small areas that project northward from New Jersey in the southeastern part of the province , •
and are described in the section on the Hudson Highlands. The Proterozoic rocks are
unconformably overlain by a belt of dolomite, limestone, and minor shale of the Cambrian-
Ordovician Wappinger Group. A thin belt of Cheshire Quartzite underlies the carbonates in the
New Milford area. Black shales with minor sandstone of the Ordovician Snake Hill Formation ,
underlie a broad area occupying the eastern two-thirds of the province. These rocks are overlain
by graywacke sandstone and black to gray siltstone and shale of the Quassaic Formation and other
Martinsburg Formation equivalents that underlie much of the southwestern part of the province.
Two narrow belts of Silurian to Devonian rocks are exposed along the southeastern edge of
the province and include the Greenpond Conglomerate; Longwood Shale; limestone, dolomite, and
shale of the Poxono Island Formation; Decker Limestone; limestone, dolomite, and sandstone of
the Helderberg Group; and shale, sandstone, and conglomerate of the Tristates Group. This
sequence is overlain by a broader belt of black shale grading upward into siltstone, sandstone, and
conglomerate of the Devonian Hamilton Group.
The Adirondacks
The Adirondacks are a complex sequence of Proterozoic sedimentary, volcanic, and igneous
plutonic rocks. These rocks were all deformed several times and metamorphosed. The High •
Peaks in the east-central portion of. the Adirondacks are underlain by anorthosite, an igneous rock
comprised almost entirely of jplagioclase with minor amounts of pyroxene, garnet, and hornblende.
Approximately 15 percent of the Adirondacks is underlain by anorthosite. Surrounding the High
Peaks are granitic gneisses, charnocMte, syenite, amphibolite, and variable rrietasedimentary
gneiss, especially in the northwestern part of the Adirondacks. Charnockitic gneiss and quartz-
poor gneiss (known as syenite) occur in several prominent complexes around the High Peaks and
in areas to the north, west, and south. These rocks underlie about a quarter of the Adirondacks
and are infolded with metasedimentary rocks and granitic gneiss. Granitic gneiss bodies are
scattered throughout the Adirondacks and make up approximately a quarter of the area Large
areas of metasedimentary rocks lie in the outermost rim of the Adirondacks, especially in the
northwest and southeast. Li total, metasedimentary rocks underlie a third of the Adirondacks.
The largest body of metasedimentary rocks is in the Northwest Lowlands, which is west of the
Carthage-Colton zone, a broad mylonite zone in the northwestern Adirondacks. The Northwest
Lowlands has broad valleys underlain by carbonate and calc-silicate rocks (Gouyerneur Marble)
and intervening ridges consisting of metasedimentary, metavolcanic, and igneous gneiss.
Metasedimentary and igneous gneisses are host to base metal deposits, most commonly iron.
IV-14 Reprinted from USGS Open-Ftfe Report 93-292-B
-------
New England Upland Province andTaconic Mountains
The northern New England Upland is mostly underlain by Cambrian and Ordovician
sedimentary rocks that are intensely deformed by folds and faults into a series of fault-bounded
thrust slices. These thrust slices are elongated to the northeast and form the Taconic Mountains.
The grade of metamorphism increases from west to east
.The oldest rocks in the province are Proterozoic leucocratic gneiss that underlie a small area
in east Dutchess County. They are unconformably overlain by the Poughquag Quartette, followed
by dolomite, limestone, and minor shale of the Cambrian Stissing Formation and the Cambrian-
Ordovician Wappinger Group. These rocks underlie a large irregular area in south-central
Dutchess County and a discontinuous irregular narrow band that trends northeastward from'
southwestern Dutchess County to east-central Columbia County. Similar-aged marble of the
Stockbridge Group forms a parallel band in eastern Dutchess County and northeastern Columbia
County. The Wappinger and Stockbridge Groups are conformably overlain by slate, phyllite, .
schist, and metagraywacke of the Walloomsac Formation, which underlies a large irregular area in
most of Dutchess County and eastern Columbia and Rehsselaer Counties. In the southwestern part
of the province the carbonates are overlain by shale and siltstone of the Snake Hill Formation.
The thrust fault sequence of rocks consists of Cambrian black slate and shale with thin
. quartzite interbeds of the Cambrian Bomoseen and Nassau Formations. These are overlain by .
black shale with limestone and conglomerate interbeds of the Ordovician Hatch Hill and Deep Kill
Formations, foUowed by red and green shale and chert of the Indian Rivers Formation and black ,
shale and chert of the Mount Merino Formation. Graywacke sandstone with black to gray siltstone
and shale of the Austin Glen Formation comprises the top of this sequence. Each of the different
thrust fault slices contains portions of this sequence and varies from slice to slice.
The Hudson Highlands
The mountains of the Hudson Highlands are part of the central and southern portion of the
New England Upland and are also part of the Reading Prong. They are divided into a western .
highlands and an eastern highlands and,consist of complexly folded and faulted metamorphic and
igneous'rocks that are host to numerous iron deposits. The western Hudson Highlands extend
from the central portion of the New York-New Jersey border, north and east across the Hudson
River to the Canopus fault zone. These rocks contain approximately equal amounts of hornblende
granite gneiss, metasedimentary and metavolcanic gneiss, and a thick sequence of quartz-feldspar
and ctiamockitic gneiss, thought to be the base of the sequence. The Storm King and Canada Hill
Granites intrude this sequence. The Storm King Granite is the more extensive granite of the two
and is predominantly a homblende-microcline granite .with aplite and alaskite. The Canada Hill
granite was formed by local melting of the rock and contains large bodies of biotite gneiss with
local xenotime and monazite concentrations. The. westernmost Hudson Highlands are composed
of two small bodies of Proterozoic rock in the southeastern part of the Valley and Ridge, west of
Green Pond Mountain. The western body is underlain by metasedimentary biotite gneiss with
quartzite, quartz-feldspar gneiss, calc-silicate rocks, and a calcitic and dolomitic marble (Franklin
Marble) interlayered with calcrsilicate gneiss. Metasedimentary biotite gneiss and granitic gneiss
also underlie a series of tiny lenticular hills along the eastern margin of the Valley and Ridge. The
eastern body is underlain by a sequence of metasedimentary, metavolcanic, and calc-silicate rocks,
including biotite gneiss, quartz-plagioclase gneiss, amphiboUte, and pyroxene gneiss. .
East of the Canopus fault; the Hudson Highlands are underlain predominantly by biotite
granodioritic gneiss and migmatite called the Reservoir Granite. Metasedimentary biotite gneiss,
IV-15 Reprinted from USGS Open-File Report 93-292-B
-------
atriphibolite, calc-silicate gneiss, pyroxene gneiss, quartz-feldspar gneiss, and small bodies of
ultramafic rock also occur in the eastern Highlands.
The Manhattan Prong
Locally along the eastern margin of the eastern Hudson Highlands, the Cambrian Lowerre
Quartzite of the Manhattan Prong lies unconformably on the Hudson Highland gneiss. In much of
the Manhattan Prong, however, it is the Yonkers, Pound Ridge, and Fordham gneiss which
underlies the Lowerre Quartzite and Inwood Marble. The folded and faulted Fordham gneiss and
Manhattan Formation are the most extensive units in the prong. The Fordham gneiss is
subdivided into several units consisting of quartz-feldspar gneiss with variable amounts of biotite,
hornblende, garnet, sillimanite, and lesser layers of amphibolite, marble, and calc-silicate rock.
The Manhattan Formation is predominantly a quartz-muscovite-biotite schist, with minor
amphibolite, marble, and quartzite. The northwestern portion of the prong is intruded by
hornblende norite and diorite of the Corttandt Complex.
Triassic Lowlands (Piedmont) •
Late Triassic-early Jurassic continental sedimentary and igneous rocks of the Newark
Supergroup are restricted to. the Newark basin. The Newark basin is a half graben with a faulted
northwestern margin. The strata dip toward the border fault and are folded into a broad syncline
that extends westward into New Jersey. Only the northeastern corner of the Newark basin is
'exposed in New York. The basal Triassic Stockton Formation forms a narrow band along the
southeastern side of the basin and consists of fluvial arkosic sandstone, conglomerate, and
siltstone. It is more conglomeratic along its basal contact with older rocks to the southeast. The
Stockton in New York is overlain by the Triassic Passaic Formation which forms most of the rest
of the basin fill. In New York, the Passaic Formation consists of lacustrine black shale and red
siltstone interbedded with deltaic gray arkosic sandstones in the lower part and fluvial red lithic
sandstones and conglomerates in the upper part. The Orange Mountain Basalt occurs in two small
synclinal folds along the border fault and consists of tholeiitic basalt flows. Jurassic diabase dikes
and sheets intrude the sedimentary rocks, most notably the Palisades sill which intrudes roughly
along the contact of the Stockton and Passaic Formations.
Atlantic Coastal Plain
The Atlantic Coastal Plain in New York covers Long Island and part of Staten Island.
Sediments of this area include glacial deposits and Cretaceous to Recent marine deposits. The
oldest sediments are Late Cretaceous in age and include marine sand and clay of the Raritan,
Monmouth, and Magothy Formations. These units are exposed in small outcrops along the
northern coast of Long Island. Recent dune and beach sands, intertidal muds, marsh mud, and
clay are common on shorelines and cover much of eastern Long Island.
GLACIAL GEOLOGY
Except for the southern part of Cattaragus County in western New York, and the southern
half of Long Island, all of New York was covered by glaciers at least once, and most areas several
times, during the Pleistocene Epoch. Almost all of the glacial deposits exposed at the surface in
New York (fig. 5) were deposited by late Wisconsinan glaciers approximately 30,000 to 11,000
years ago (Cadwell, 1988). However, older glacial deposits are locally found underlying
IV-16 Reprinted from USGS Open-File Report 93-292-B
-------
-------
GENERALIZED GLACIAL MAP OF NEW YORK
EXPLANATION
Ice-contact stratified deposits—sorted and stratified gravel, sand, and silt,
includes deposits of kames, kame moraines, kame terraces, outwash,
glaciolacustrine and marine deltas, esker>s; locally includes alluvium
Silt and clay glacial lake and marine deposits—sorted and stratified fine sand, silt,
and clay of lake bottoms and shallow marine environments
$$$ Sandy glacial lake and marine deposits—sorted and stratified fine to coarse
sand of shallow lake and marine environments and beaches
| | Till—unstratified, poorly sorted to unsorted mixture of gravel, sand, silt, and
clay
yl l| Unglaciated area •
-------
Wisconsinan-age deposits or intermixed with younger outwash or moraine deposits. New York
was occupied by three main glacial lobes during late Wisconsin time—the Ontario-Erie lobe in
western New York, the Ontario lobe in the central part of the State (Fullerton, 1986; Richmond and
Fullerton, 1991), and the Hudson-Champlain lobe in eastern New York (Cadwell and Dineen,
1987; Cadwell, 1989). Much of the glacial drift is locally derived and generally reflects the
litholqgy of the underlying parent bedrock, although most tills include lesser amounts of material
derived from bedrock source areas to the north.
Glacial deposits in New York can be generally classified into five categories: till, moraines,
kame deposits, outwash and alluvium, and glacial lake deposits. Till varies from 1 to 50 meters .
thick and commonly covers flat of upland areas. The tills have variable texture, from clay through
silt and sandy clay to boulder clay, and have generally low permeability. Tills are sandy in areas
underlain by sandstone, granite, or gneiss (Cadwell and Dineen, 1987). Till moraines and kame
moraines were formed at the margins of the, retreating ice bodies. Moraines are linear or arcuate
ridges of material that is variable in sorting and in grain size, typically containing sand to boulders;
they usually contain less fine-grained material and thus are generally more permeable than till,
especially kame moraines. Kame deposits (which include kames, eskers, and kame deltas) are
composed of coarse to fine gravel and sand left by rivers and streams flowing along the margins,
surface, or beneath the glacial ice. These deposits have moderate to high permeability, but may
have lower permeability where they are locally cemented. River valleys are typically filled with
alluvium or outwash sand and gravel deposits. Lacustrine (lake) deposits are composed of clay,
. silt, and locally, sand and are formed in valleys dammed by glacial ice. These deposits generally
have low to moderate permeability. Glacial lake deposits often occupy low-lying areas, including
the Erie-Ontario, St. Lawrence, Hudson-Mohawk, and Champlairi Lowlands. Lacustrine beach
and delta deposits occur locaUy at the margins of former glacial lakes and are composed of .
permeable sand and gravel. The following summary of surficial geology of New York is
condensed and generalized from the surficial geologic map of New York and other reports
(Cadwell, 1988,1989; Cadwell and Pair, 1991; CadweU.and Dineen, 1987; MuUer and CadweU,
1986). The reader is urged to consult these maps and reports for more detailed information.
Glaciers in eastern New York moved primarily north-south or northeast-southwest The
Adirondack Mountains diverted the continental ice sheet to the east and west while valley glaciers
formed in the mountains (Muller, 1965). The glaciers moved southward along the Hudson-
Mohawk Valley, terminating on Long Island and in northern New Jersey. As the Hudson-
Champlain lobe retreated northward, a glacial lake called Lake Albany formed, filling the entire
Hudson Valley. At its maximum extent, Lake Albany reached a length of about 224 km and a'
width of 13-20 km (Cadwell and Dineen, 1987). As a result, much of the floor of the Hudson
Valley is occupied by glaciolacustrine silts and. clays. Lacustrine delta deposits composed of sand-
and gravel are found along Kinderhook Creek, the Hoosic River, in the Batten Kill, and along the
Mohawk River. The Champlain Valley was occupied at various times by three glacial lakes:
Quaker Springs, Coveville, and Fort Ann (Connally and Sirkin, 1973).
Till of variable thickness covers much of eastern New York. Deposits of drift in the
valleys are thicker (up to ,100 m) than those in the uplands (generally less than 5 m). Coarse-
grained glacial drift partly fills most valleys in the Adirondacks. Glacial deposits are thin or absent
in parts of the Taconic Mountains, Hudson Highlands, and Catskill Mountains. Moraines run the
length of Long Island and indicate the maximum advances of the Hudson-Champlain lobe on
western Long Island and the Connecticut and Rhode Island lobes on central and eastern Long
Island (CadweU, 1989).- ,
IV-19 Reprinted from USGS Open-File Report 93-292-B
-------
Glacial erosion and deposition in central and western New York were most extensive in the
Erie-Ontario Lowland and in the east-west belt of arcuate-uplands that includes the northern part of
the Finger Lakes. To the south, glacial modification of the landscape becomes progressively less
intense (Muller and Cadwell, 1986). Except for bedrock exposures.in uplands of the Finger Lakes
region and on steeper slopes in the south-central and western parts of the State, the landscape of
central and western New York is covered by a mantle of glacial deposits ranging in thickness from
a few meters in upland areas to several hundred meters in valley bottoms. As the la°te Wisconsinan
ice margin retreated north of the bedrock divide comprising the Finger Lakes region, meltwater
was impounded in the many glacially-carved valleys that are now the Finger Lakes. Several minor
ice advances failed to extend south of the divide, and these fluctuations built a complex of coarse-
grained, poorly sorted moraines, called the Valley Heads Moraine, which extends in an arcuate
east-west belt along the southern edge of the Finger Lakes (Muller arid Cadwell, 1986).
As a result of these processes, the character of the glacial deposits in central and western
New York changes from mostly till in the south, with alluvium, outwash, and abundant kame
terraces filling stream valleys, to moraines and kame deposits in the Finger Lakes region, with
bedrock exposures in the uplands and deposits of glacial Lake Newberry in the troughs of the
Finger Lakes, to deposits of glacial Lake Iroquois in the Erie-Ontario Lowland. Lacustrine clays
are the primary deposit type along the shores of Lakes Erie and Ontario, surrounding the southern
part of Lake Oneida, and at the northern ends of most of the Finger Lakes. Sandy lake deposits ,
surround the northern, eastern, and western sides of Lake Oneida, the northern ends of Seneca and
Keuka Lakes, and are found south and west of Rochester. Interspersed with deposits of Lake
Iroquois are outwash, kames, moraines, drumlins, and other features typical of kame-and-kettle
topography (Muller and Cadwell, 1986).
SOILS
Three main orders—Alfisols, Ihceptisols, and Spodosols—represent most of the soils in
New York, although Entisols, Ultisols, and Histosols are also found in significant amounts (U.S.
Soil Conservation Service, 1987; Cline and Marshall, 1977). Figure 6 is a generalized map
showing soils of New York. The following discussion is condensed primarily from Cline and
Marshall (1977); the reader is urged to consult this report or U.S. Soil Conservation Service
county soil surveys for more detailed maps and descriptions of soils for specific areas within the
State. *' . . • . '
Soils in the Adirondacks are mostly Spodosols, soils with light-colored, eluvial near-
surface horizons and accumulations of iron and humus in the subsurface. These acidic soils are
derived from mafic metamorphic rocks; metasediments; some granites and granitic gneisses; and
glacial deposits derived from these rocks. Most of the Spodosols in New York are coarse loamy
or sandy in texture, and those developed in glacial till are stony or bouldery. Most of these soils
have significant clay accumulations or fragipans in the subsurface, causing them to be poorly
drained and slowly permeable (Cline and Marshall, 1977), although most of these soils likely have
moderate to high permeability below the B horizon. Wet soils occur in northern Franklin and
Clinton Counties, in a north-south trending band in central Lewis County, and in northwestern
Lewis County and adjacent areas in Jefferson County. Some parts of the Adirondacks and
Hudson Highlands have rock outcrops at the surface with no discernible soil cover.
. IV-20 Reprinted from USGS Open-File Report 93-292-B
-------
O
s
-I
•8
1
I
I
"3
S.
§
O
vo.
ft.-
-------
GENERALIZED SOIL MAP OF NEW YORK
EXPLANATION
Clayey and loamy soils, and soils with fragipans developed on
glacial till derived from limestone and shale - low permeability
Coarse-textured, shallow, stony soils, and deeper soils with
fragipans, developed on glacial till derived from shale, siltstone,
sandstone, and conglomerate - low to moderate permeability
Stony, coarse-loamy and sandy soils with fragipans developed
on glacial till derived from metamorphic rocks - low
permeability. Includes large areas of bedrock with little or no
soil cover
Sandy and gravelly soils developed on glacial outwash, kames,
moraines, deltas, and alluvium - dominantly high permeability,
locally moderate permeability
Clayey and silty soils with clayey subsurface horizons
developed on glacial lake deposits - low to locally moderate
permeability .
Urban land - unknown or variable soil characteristics
-------
Soils in the St Lawrence Lowland, the northern part of the Erie-Ontario Lowland, the;
Champlain and Hudson Valleys, and northward-draining valleys of the Allegheny Plateau are
Alfisols derived from glacial lake and marine sediments, these soils are commonly calcareous and
have clayey subsurface horizons. Because of their silty to clayey texture and the presence of clay
horizons, these soils have low permeability; however, soils formed on dominantly silty lake
deposits have moderate permeability. With the exception of the northern part of the Erie-Ontario
Lowland from eastern Orleans County to Oswego County and the southern part of the Hudson
River valley, these soils are classified as occasionally to typically wet.
Soils in the remainder of the Erie-Ontario Lowland, the Mohawk Valley, and the Finger
Lakes region of the Allegheny Plateau are Alfisols developed on glacial till derived from limestone,
dolomite, and shale, these soils are commonly calcareous and contain subsurface clay horizons.
SoH texture ranges from loamy to finely loamy in soils developed from carbonate-rich till to clayey
in soils developed on shale-rich tills. Most of these soils are slowly permeable, but a few of these
soils north of the Finger Lakes region are classified as moderately permeable. Soils in the eastern
Mohawk Valley, parts qf the Finger Lakes region, and in the western part of the Allegheny Plateau
are classified as commonly wet.
Soils of 'the Allegheny Plateau are shallow to deep Inceptisols developed on glacial till
derived from sandstone and shale, including black shale. These soils are generally acidic
throughout the profile and contain carhbic horizons, leached zones with thin iron oxide coatings on
sand and silt grains. Approximately half of the. soils in this area have fragipans in the subsurface
that act as a barrier to air and water migration in the soil. Soil texture ranges from sandy and
; gravelly in soils developed on coarse-grained till to clayey in soils developed on shale-rich till.
'Soil permeability ranges from moderately high to low and generally follows'soil texture, i.e., _
coarser-grained soils generally have higher permeability, except those soils with fragipans, which
are uniformly poorly drained and are considered to have low permeability. Wet soils are common
in the western and central parts of the Allegheny Plateau region. Soils in the New England Upland
are similar to those in the Allegheny Plateau except that they are developed on glacial till derived
:from carbonate rocks and metasedimentary rocks as well as sandstones and shales. Soils classified
as wet are less common in the New England Upland than in the Allegheny Plateau region.
Soils of the Valley and Ridge are acidic Alfisols with fragipans and clayey horizons. These
soils are developed on glacial till derived from limestone, dolomite^ sandstone, siltstone, and shale.
These soils have generally poor internal drainage and low permeability, and are typically wet
unless situated on slopes. However, soils derived from coarser-grained parent materials may have
moderate to locally high permeability beneath the fragipan. Soils of this same classification also
occur in the southern Finger Lakes region and in the western part of the Allegheny Plateau.
'Soils in.the Triassic Basin are acidic Inceptisols with fragipans below cambic horizons.
: These soils are developed on glacial till derived from sandstone, siltstone, shale, metasedimentary
rocks, and intrusive igneous rocks. They are poorly drained and have low overall permeability due
to the presence of fragipans, but may have moderate permeability beneath the fragipan layer. Soils
"', of the Manhattan Prong are acidic Inceptisols with cambic horizons developed on glacial till derived
from sandstone, shale, marble, gneiss, schist, amphibolite, and quartzite. Soil.cover ranges from
shallow to none (rock outcrops). These soils are generally sandy to gravelly and have moderate to
high permeability..' Soils of Long Island and the New York City area are Inceptisols developed on
glacial outwash, alluvium, arid marine sediments. They are typically sandy to gravelly, well
drained, and rapidly permeable. , .
IV-23 Reprinted from USGS Open-File Report 93-292-B
-------
RADIOACTIVITY
An aeroradiometric map of New York (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)
on the map 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, low eU (<1.5 ppm), is found
throughout the Erie-Ontario Lowland. The Adirondacks have generally low surface eU with the
exception of the metasedimentary rocks that form the outer edge of the Adirondacks, especially in
the Northwest Lowlands. The Tug Hill Plateau and Champlain Lowland are also low in
radioactivity. The St. Lawrence Lowland has low to moderate eU. Moderate eU covers much of
the Allegheny Plateau with some low eU areas along the northern edge of the plate'au. Moderate to
high eU is found throughout the New England Upland, the Hudson-Mohawk Lowland, the
Hudson Highlands, part of the Triassic Lowland, and the Manhattan Prong. High eU is associated
with the Catskill Mountains of the Allegheny Plateau, the southern Allegheny Plateau, the Valley
and Ridge, parts of the Hudson Highlands, and parts of the Taconic Mountains.
INDOORRADON
As part of their statewide indoor radon testing program, a number of different indoor radon
surveys have been conducted and compiled by the State of New York since 1985. For the .
assessment done by the authors of this report, volunteer basement and first-floor indoor radon data
from 39,070 charcoal canister tests across New York State were used. These data were supplied
by the New York State Department of Health, duplicates were eliminated from the original data set
and the resulting data set is given in Table 1. These data are also presented in map format in
figure 8. A map of county names is included for reference (fig. 9). The average for the State in
this data set is 5.2 pCi/L. Thirty percent of the measurements were greater than 4 pCi/L and 5
percent of the measurements exceeded 20 pCi/L The data were compiled over several years and
several seasons. Because these data are statistically non-random, the arithmetic mean will tend to
be biased towards higher readings (Cohen, 1990). However, these data do emphasize distinct
areas of low and high radon in the State and provide some distinction within the higher radon
categories, especially when comparing the average and geometric means for each county. Areas of
the State with county indoor radon geometric means greater than 4 pCi/L occur in the Allegheny
Plateau and New England Upland, particularly the Taconic Mountains. Geometric means between
2 and 4 pCi/L occur in the Allegheny Plateau, Hudson-Mohawk Lowlands, Tug Hill Plateau, and
Hudson Highlands. Geometric means less than 2 pCi/L occur in the St. Lawrence-Champlain
Lowlands, the High Peaks, and much of the Adirondacks, much of the Erie-Ontario Lowlands, the
Manhattan Prong, the Triassic Lowlands, and the Atlantic.Coastal Plain.
New York State has also conducted a statewide random survey of more than 2000 homes
using alpha-track detectors (Perritt and others, 1988). They divided New York into seven areas
(fig. 10) based on geologic and geographic factors and placed several detectors in each home for
several periods of time. Table 2 shows the statistics for two-month winter .alpha-track data placed
in the living area of the home. Table 3 shows 12-month alpha track data placed in the living area of
the homes. Table 4 shows 12-month alpha track data placed in the basement of the same homes.
Areas 1,2, and 7 were consistently above the average for the State for each data set. The highest
average alpha-track measurements were found in area 1, the eastern-southern tier underlain by the
IV-24 Reprinted from USGS Open-File Report 93-292-B
-------
-------
22
Bsmt. & 1st Floor Rn
'%>4pCJ/L ,
OtolO
11 to 20
21 to 40
1 1 mmm 41 to 60
3 M 61 to 80
27
Bsmt. & 1st Floor Rn
Average Concentration (pCi/L)
11
0.0 to 1.9
20 KXNXN 2.0 to 4.0
4.1 to 10.0
4 M 10.1 to 14.2
Figure 8. Screening indoor radon measurements from 39,070 homes, compiled by the New York
State Department of Health. Data are from 2-7 day charcoal canister measurements. Histograms in
map legends show the number of counties in each category.
-------
Bsmt. & 1st Floor Rn
Geometric Mean (pCi/L)
0.0 to 1.0
1.1 to 1.9
2.0 to 3.0 •' ..'
3.1 to-4.0
4.1 to 6.0
6.1 to 8.0
Fig. 8 continued
-------
Table 1. Screening indoor radon data compiled by the New York State Department of Health.
Data represent Ir7 day charcoal canister measurements from the lowest level of each home
tested. . '
COUNTY
Albany
Allegany
Bronx
Broome
Cattaraugus
Cayuga
Chautauqua
Chemung
Chenango
Clinton
Columbia
Cortland
Delaware
Dutchess
Erie
Essex
Franklin
Fulton
Genesee
Greene
Hamilton
Herkimer
Jefferson
Kings
Lewis
Livingston
Madison
Monroe
Montgomery
Nassau
New York
Niagara
Oneida
Onondaga
Ontario
Orange
Orleans
Oswego
Otsego
Putnam
Queens
Rensselaer
Richmond
NO. OF
MEAS.
1183
212
1123
1826
394
440
651
1195
255
132
304
380
348
2454
4671
122
71
103
339
137
20
147
127
1123
56
139
265
1298
147
589
1123
712 . .
729
4749
352
1098
476
170
494
624
1123
648
1123
AVERAGE
3.7
10.2
1.4
5.7
6.5
4.4
5.3
12.4
8.5
2.2
. 7.0
14.2
7.0
6.3
4.4
1.5
1.3
2.1
7.7
4.4
1.6
4.6
3.0
1.4
4.4
6.2
4.8
2.8
3.6
1.2
1.4
1.7
5.1
8.5
5.3
4.5
3.2
2.0
8.0
4.0
1.4
6.4 '
1.4
STD.
DEV.
8.3
14.0
2.0
13.1
12.4
7.0
9.4
13.6
13.8
3.3
18.0
15.1
13.8
8.0
14.2
2.7
1.3
2.3
20.6
8.4
1.5
6.1
4.2 '
2.0
4.9
9.3
6.8
8.4
4.5
1.2 •
2.0
2.2
7.6
16.2
10.1
6.8
6.3
2.9
17.4
5.6
2.0
9.4
2.0
MEDIAN
1.5
4.7
0.8
2.4
2.7
2.5
1.9
7.6
3.6
1.3
3.8
9.9
2.8
4.1
1.1
0.9
0.9
1.4
3.1
2.1
1.0
2.5
1.6
0.8
2.5
3.5
2.7
1.4
1.9
1.0
0.8
1.0
2.5
3.6
2.4
2.5
1.7 •
1.2
4.2
2.3
0.8
3.5
0.8
GEOM.
MEAN
1.6
4.6
0.8
2.6
.3.0
2.5
2.2
6.9
3.8
1.2
3.6
8.0
3.1
3.8
1.3
0.9
0.8
1.3
3.4
2.1
1.0
2.5
1.5
0.8
2.5
3.4
2.6
1.5.
2.0
0.9
0.8
1.0
2.6
3.7 '
2.7
2.4
1.7
1.3
3.8
2.2
0!8
3.3
0.8
MAX
100.6
113.7
21.9
319.9
119.4
81.9
.102.1
98.4
105.5
23.2
298.0
107.4
152.4
135.2
371.9
26.3
6.2
13.5
322.7
72.4
5.5
44.2
28.8
21.9
26.4
76.6
57.7
214.4
32.7
9.6
21.9
17.3
79.0
341.8 ,
125.0
85.5
86.4
29.6
299.7
47.5
21.9
103.2
21.9
%>4 pCi/L
19
55
5
35
40
31
31
69
47
13
49
73
39
51
18
' 5
3
12
39
28
. 10
33
23
5
41
47
35
12
31
3
5
8
35
47
32
. 33
18
9
52
31
5
46
5
%>20 pCi/L
3
17
0
5
6
3
4
21
11
1
6
23
7
4
4
1
0 .
0
8
3
0
3
1
0
2 '
4
4
2
1
0
0
0
4
10
5
3
.2
1
7
2
0
5
0
-------
Table 1 (continued).
COUNTY
Rockland
St. Lawrence
Saratoga
Schenectady
Schoharie
Schuyler
Seneca
Steuben
Suffolk
Sullivan
Tioga
Tompkins
Ulster
Warren
Washington
Wayne
Westchester
Wyoming
Yates -
NO. OF
MEAS.
2469
195
578
506
'•' 151
70
• 144
593
356,
154
, 541
460
, 596
.121
119
142
2365
233
97
AVERAGE
2.2
• 2.3
3.2
3.0
5.4
4.0
2.5
; 11.2
1.6
3.1
8.3
4.4
4.0
2.1
4.7 •
3.8
, 2.4
8.9
5.8
STD.
DEV.
4.3
4.5
5.1
6.0 -
8.8
3.4
2.9
14.6
2.6
4.6
14.9
5.8
7.9
2.5
7.1
5.8 '
3.8
14.7
9.3
MEDIAN
1.3
1.4
• 1.8
1.7
2.8
3.1
1.7
. 5.8
1.1
1.8 ,
3.7
2.6
2.3
1.4
2.1
1.8
1.5
.3.9
2.8
GEOM.
MEAN
1.3
1.3
1.8
1.7
2.7
2.7
1.6. .
5.5
1.0
, 1.7
3.8
2.7
2.2
1.3
2.3
2.0
1.5
4.1 '
2.8
MAX
123.7
56.8
56.9
84.9
58.9
18.5
19:5
133.4
42.6
38.0
236.8
54,6
114.3
20.1
43.6
35.3
95.4
,.. 13714 .
69.0
%>4pCi/L
11
12
20
19
38
40
15
63
6
21
48
.32
28 •
10
' 29
20. .
13 .
48
38
%>20 pCi/L
1
1
1
1
5 '
0
0
17
0
2
, 9
2
2
'. -' 1
3
' : 4
1
12
: 5 •
-------
oo
ON ,
-PL,
o'
GO
4->
O
O-
3
O
O
I
I
s
-------
Table 2. Weighted summary statistics for the New York State short-term, living-area
radon study, overall and by geographic region. .Values in pCi/L (from Perritt and others,
1988).
REGION
State
Eastern &
Southern
Tier
Central &
Western
North-
eastern
Eastern
Staten
Island
Long
Island
New York
City
SAMPLE POPULATION
SIZE ESTIMATE
2401 •
346
767
545
276;
51
335
81
2,600,830
82,929
1,078,804
137,452
374,910
58,676
563,816
304,243
MEAN
1.39
3.34
1.58
1.09
1.82
0.75
0.87
0.81
STD.
ERROR
0.05
0.30
0.10
0.08
0.18
0.06
0.04
0.08
Table 3. Weighted summary statistics for the New
study, overall and by geographic region. Values in
REGION
State
Eastern &
Southern
Tier .
Central &
Western
North-
eastern
Eastern,
Staten
Island
Long
Island
. New York
City
SAMPLE POPULATION
SIZE ESTIMATE
2043
307
655 ,
465
238
41
273
64
2,598,722
81,810
1,075,537
137,475
377,165
58,408
563,816
304,512
MEAN
1.13
2.65
1.33
0.88
1.51
0:55
0.68
0.64
STD.
'ERROR
0.05
0.26
0.08
0.06
0.15
0.06
0.04
0.10
MEDIAN
0.86
i;31
0.95
0.81
1.06
0.63
0.73 .
0.78
90th
PERCENTILE
2.51
8.81
3.21
1.86 '
3.42
1.22
1.75
1.46 '
MAXIMUM
39.8
39.8,
28.4
21.6
: 20.9
2.4
3.4
2.4
York State long-term, living-area radon
pCi/L (from Perritt and others, 1988).
MEDIAN
0.6
1.2
0.8
0.6
0.9
0.4
0.5
0.5
90th
PERCENTILE
2.2
6.0
2:7
1.7
3.2
1.1
1.2
1.4
MAXIMUM
38.3
38.3
21.7
9.5
16.2
2.3
7.4 .
5.1
-------
Table 4. Weighted summary statistics for the New York State long-term, basement radon
study, overall and by geographic region. Values in pCi/L (from Perritt and others, 1988).
SAMPLE POPULATION
REGION
State
Eastern &
Southern
Tier
Central &
Western
North-
eastern
Eastern
Staten
Island
Long
Island
New York
City
SIZE
1716
262
561
371
199
35
231
57
ESTIMATE
2,187,865
70,186
912,234
112,241
300,925
46,836
461,512
283,929
MEAN
2.68
6.58
3.05
2.56
4.02
1.35
1.49
1.30
STD.
ERROR
0.13
0.69
0.25
0.35
0.36
0.17
0.08
0.13
MEDIAN
1.4
3.6
1.5
1.3
2.2
1.2
1.2
1.1
90th
PERCENTTLE
.5.3
14.7
6.7
4.4
9.0
3.2
2.9
2.4
MAXIMUM
115.0
115.0 '
52.9
65.7
31.5
3.6
6.5
3.5
Legend
1 East/Southern Tier
z Central and Western
3 Northeastern
4 Staten Island
5 Long Island
6 New YsrkCIty
7 Eastern
Rgure 10. Map showing the 7 geographic regions used in the above tables by Perritt and others (1988).
-------
shales and sandstones of the West Falls,' Sohyea, and Genesee Groups. Coarse glacial gravel
deposits in valleys are also common in this area. The area with the second highest average
measurements is area 7, which is underlain by metamorphic, igneous, and deformed sedimentary
rocks of the Taconic Mountains, Hudson Highlands, Valley and Ridge, and Manhattan Prong, as
well as the undeformed sediments of the Triassic Lowlands. Area 2, the central and western area,
had alpha-track measurements that averaged greater than the State average. This area is underlain
by undeformed shales, sandstones, siltstones, and carbonates. Perritt and others (1988) also noted
a distinct difference between the 12-month and 2-month measurements. They observed that the
12-month living area measurements were higher than the 2-month winter living area measurements
and that the 12-month basement measurements were the highest in the data set.
GEOLOGIC RADON POTENTIAL
^ '" . ' • * » . •
Several studies have been conducted in New York State relating the geology of the State to
indoor radon occurrences. The most comprehensive of these was done by the New York State
Department of Health (Laymoh and others, 1990). In their study, the authors examined the indoor
radon, geology, radioactivity, and soil data to arrive at general potential ratings for geologic
provinces within the State. Other studies have concentrated on particular areas of the State with
high radon (Kunz and others, 1987; Kunz and others, 1989; Laymon and Kunz, 1991; Hand and
Banikowski, 1988a, 1988b; Schwenker and.others, 1992).
The following section discusses the geologic radon potential of New York in the context of
the data presented thus far and radon studies conducted by the State. A scoring system for
geologic radon potential is presented in Table 5 following this section. -Table 6 lists the counties of
the State, the major geologic province and indoor radon average of the county, and highlights
counties with more than one province of contrasting radon potential and the possibilities for
variations in indoor radon within the county.
The Erie-Ontario Lowland/Tug Hill Plateau
The Erie-Ontario Lowland and Tug Hill Plateau are underlain by a flat-lying sedimentary
sequence with abundant limestone, dolomite, shale, sandstone, and distinctive salt deposits.
Equivalent uranium (fig. 7) is generally low to moderate in this area. Counties in the Erie-Ontario
Lowland have indoor radon geometric means less than 2 pCi/L and average concentrations of
indoor radon less than 4 pCi/L. Lewis County is the exception in that the indoor radon average is
4.4 and the geometric mean is 2.5 pCi/L. A veneer of impermeable clay covers a significant part of
the Erie-Ontario Lowland^ but discrete, occurrences of very coarse gravel and some of the marine
shales may cause some of the moderate and locally high radon measurements found in the area.
Laymon arid others (1990) ranked the Erie-Ontario Lowlands as having low radon source strength,
low permeability, and consequently low radon potential, but the authors indicate that radon
potential is high in association with gravels in drumlins, outwash, moraines, till, and beach ridges.
Significant accumulations of these coarse glacial deposits occur in Wayne County and in the
eastern portion of the province around the Tug Hill Plateau. We have assigned an overall moderate
radon potential to the area based on the majority of county indoor radon averages being greater than
2 pCi/L, the variably low to high radon source potential of the geology, variably low to high
permeability, and low to moderate radioactivity. ,
W-33 Reprinted from USGS Open-File Report 93-292:B
-------
The Hudson-Mohawk Lowland
The Hudson-Mohawk Lowland is underlain by sandstone, siltstone, shale and.
conglomerates of variable age. In this assessment, the lowland has been ranked moderate/variable
in radon potential because the geology and glacial deposits of the area are highly variable and radon
potential varies likewise from low to high. Equivalent uranium (fig. 7) is generally moderate to
locally high in this area. Soils have moderate to locally high permeability. Counties in the
Hudson-Mohawk Lowland have indoor radon geometric means in the low to moderate range (less
than 3 pCi/L), and average concentrations of indoor radon between 2 and 4 pCi/L (fig. 8). Kunz
and others (1989) discovered high levels of indoor and soil radon associated with the coarse gravel
deposits in Albany County. In their study, the geometric mean for 675 basement indoor radon
measurements in Albany County was 20.2 pCi/L for homes built on glacial gravels. Schwenker
and others (1992) have done a detailed study in Albany County using a Geographic Information
System mapping program and looking at surficial geology and indoor radon. They confirmed the
results of the study by Kunz and others (1989) and further delineated areas of low and moderate
radon in the county and the associated glacial deposits. Schwenker and others (1992) found
indoor radon geometric means for lacustrine delta and kame deposits were 3.6 pCi/L and 3.2 pCi/L
respectively. Homes built on recent floodplain deposits and lacustrine silt and clay had indoor
radon geometric means of 1.5 pCi/l and 1.1 pCi/L respectively. The indoor radon geometric
means for lacustrine sand and dune sand were both 0.9 pCi/L. The New York State Department of
Health is intending to extend their Geographic Information Systems-based study of indoor radon to
•the rest of New York State. • •
Laymon and others (1990) have suggested that the Hudson-Mohawk Lowland is highly
variable in radon potential but that the gravelly kame and till deposits found above the valley
bottoms and gravel concentrations in sandy glacial deposits are high in radon potential: They also
note that the region is underlain predominantly by shale with average to below-average radium
concentrations and that indoor radon over the shales is generally low.
The St. Lawrence and Champlain Lowlands
The St. Lawrence and Champlain Lowlands are underlain by sedimentary rocks of
Cambrian through early Ordovician age with relatively low radon potential. However, some of the
very coarse gravel deposits have moderate to high radon potential. Equivalent uranium (fig. 7) is
generally low with a few moderate areas. Counties in the lowlands have indoor radon geometric
means less than 2 pCi/L and average concentrations of indoor radon less than 3 pCi/L. The
Cambrian rocks are dominantly conglomerates and coarse sandstones, known as the Potsdam
Sandstone. In the basal conglomerate of the Potsdam, local accumulations of monazite, a uranium-
and thorium-bearing mineral, occur. The rest of the section consists of siltstone, dolomite,
limestone, shale, and 'sandstone that are relatively low in uranium. A veneer of impermeable clay
covers much of the area; however, areas of highly permeable, very coarse glacial gravels and
gravel in beach ridges may cause some of the moderate to high radon levels found in the area.
Laymon and others (1990) ranked the St. Lawrence-Champlain Lowlands as having low radon
source strength, low permeability, and consequently low radon potential. They also indicate that
local occurrences of elevated (>4 pCi/L) indoor radon are associated with gravels in drumlins,
outwash, moraines, till, and beach ridges. Because of these highly permeable.deposits and county
average radon greater than 2 pCi/L these provinces are ranked moderate in radon potential.
IV-34 Reprinted from USGS Open-File Report 93-292-B
-------
The Allegheny Plateau
The Allegheny Plateau is underlain by sedimentary rocks, predominantly shales,
limestones, and sandstones. Soils in the southern plateau have low to moderate permeability
except for glacial gravel deposits, primarily in valleys, which have high permeability., In the
northern plateau, the soils have low permeability with the exception of local glacial gravels. The
plateau has been ranked high in radon potential overall. However, parts of the Allegheny Plateau
are moderate to low in radon potential, especially areas in the Catskill Mountains. Equivalent
uranium (fig. 7) is generally moderate in the plateau and is high along the south-central border with
Pennsylvania. The radioactivity pattern may correspond to the geometry of the Valley Heads
Moraine in the Finger Lakes:region, with thinner till and progressively higher radioactivity south of
the moraines. The central and southern portions of the plateau have high radon potential in
association with coarse kame, till, and other gravel deposits which are restricted generally to
valleys. Two belts of uraniferous black shale cross central and southern New York and cause
significant high indoor radon from Onondaga County to Erie County. The Marcellus Shale and
West Falls Group shales appear to be the source for this radon. Uranium and radium
concentrations in these shales are high (Laymon and others, 1990) but variable. Laymon and
others (1990) also note that other black shales and related sedimentary rocks in the plateau do not
appear to have as high a uranium content Studies of radon in Onondaga County by Laymoh and
Kunz (1991) indicate that high indoor radon is related to the uraniferous Marcellus Shale and also
related to gravelly glacial deposits and high permeability zones around the substructure of houses
built into limestone bedrock. Hand and Banikowski (1988a, 1988b) speculate that elevated indoor
radon concentrations near the contact between the Onondaga limestone and'the Marcellus Shale are
due to remobilization of uranium from the shale into the fractured limestone,' Of the northern
counties in the Allegheny Plateau, ,Seneca County is the only county with an indoor radon average
less than 4 pCi/L and it is considered moderate in radon potential. The northern, more populous
portion of Seneca County is underlain by glacial clays and the rest of the county is covered by till.
According to Kunz and others (1989) and Laymon and others (1990), gravelly glacial
deposits are the cause of most of the high radon found in the southern plateau, probably due to
high permeability and radon emanation. Their field studies indicate that gravelly soils with a silty
loam matrix are probably the source for the highest indoor radon. Because the alluvial valley and
moraine deposits are discrete bodies (fig. 5), categorizing whole counties as high in radon potential
may not be accurate. In addition, many towns are built in the valleys, on the deposits most likely
to cause high radon, and most of the indoor radon data available for the counties comes from these
towns. Further work is needed outside of the towns located in the valleys to accurately evaluate
the uplands and counties as a whole. Since many of the uplands are highly fractured shales, there
is a geologic potential for elevated indoor radon. •
Devonian sandstones in the eastern portion of the plateau and Catskill Mountains are
variable in uranium concentrations—some may locally contain up to 53 pprii (Way and Freidman,
1980), but generally the sandstones are in the 1-2 ppm range. Sullivan County, which is mostly
located in the Catskill Mountains, has lower indoor radon than surrounding counties with an
averageof 3.1 pCi/L and geometric mean,of 1,7. This county is considered to. have moderate
radon potential.
Most counties.in the Allegheny Plateau have indoor radon geometric means in the 2-4 pCi/L
range and county averages > 4 pCi/L. Four counties—Allegany, Chemung, Corfland, and
Steuban^-have indoor radon county averages exceeding 10 pCi/L. ,
IV-35 Reprinted from USGS Open-File Report 93-292-B
-------
The New England Upland-Hudson Highlands. Taconic. Mountains, and Manhattan Prong
The Hudson Highlands, which are the northeastern extension of the Reading Prong, has
been ranked high in radon potential, but the radon potential is actually highly Variable. These
mountains contain a wide variety rock types and compositions. Equivalent uranium (fig. 7) is
generally moderate with local lows and highs. Soils are thin and stony with locally thick
accumulations of low permeability till. Numerous uranium localities and associated gamma-ray
anomalies are well documented in the Hudson Highlands by McKeown and Klemic (1953); Prucha
(1956), Klemic and others (1959), Grauch and Zarinski (1976), Grauch (1978), and Gundersen
(1984,1986). Uraninite and other U-bearing minerals form layers and disseminations in several
kinds of host rocks, including magnetite deposits, pegmatites, intrusive granitic rocks, marble,
veins, and biotite-garnet gneiss with layers of monazite and xenotime. Uranium mineralization in
the gneisses and magnetite deposits is often conformable with the compositional layering and is
localized. These uranium deposits appear to be the cause for local occurrences of very high indoor
radon levels. Faults and shear zones in the Highlands are also host to uranium mineralization and
are well known throughout the Appalachians for causing high indoor radon levels (Gundersen,
1991). New York State has compiled a brittle structures map for the State (Isachsen and
McKendree, 1977) and faults may be an important radon source in parts of the Adirondacks and
New England Uplands.
Rock types which tend to be low in uranium in the Hudson Highlands include amphibolitic
gneisses, quartz-poor gneisses, and some marbles. Because the composition and location of very
high concentrations of uranium in these rocks is so variable* indoor radon is likewise highly
variable. The Hudson Highlands underlie parts of Putnam and Orange Counties that have county
indoor radon geometric means of 2.4 and 2.8 pCi/L respectively (Table 1) and county indoor radon
averages greater than 4 pCi/L. Laymon and others (1990) have ranked the Hudson Highlands high
in radon potential because of the very high indoor radon levels found in some homes, because
many of the homes are built into bedrock, and because high levels of radon in well water also
occur.
The Manhattan Prong is made up of metamorphic and igneous rocks with generally low
amounts of uranium and low radon potential. No direct correlation between any of the Manhattan
Prong rocks and indoor radon has been made. Equivalent uranium is generally low to moderate
(fig. 7). Soils have low to moderate permeability. Counties underlain by the Manhattan Prong
(Westchester County and most of New York City) have indoor radon geometric means < 1.5 pCi/L
and average indoor radon < 2.4 pCi/L (fig. 8). Laymon and qthers (1990) ranked the Manhattan
Prong low in radon potential and we concur in this assessment. .
The Taconic Mountains-New England Upland area is underlain predominantly by slate,
phyllite, graywacke, and limestone. This area has been ranked high in radon potential. The
county geometric means for indoor radon in this province are greater than 2 pCi/L and the county
averages are greater than 4 pCi/L. Equivalent uranium (fig. 7) is moderate to locally high. Soil
permeability is low to moderate, with locally high permeability in glacial gravels, Laymon and ,
others (1990) classified the region as having moderate potential but he also states that little is
known about the indoor radon in the area. In their limited studies, Kunz and others (1989)
showed that high indoor radon appears to be related to highly permeable glacial and fluvial
sediments along the valleys of the New England Upland.
IV-36 Reprinted from USGS Open-File Report 93-292-B
-------
Adirondack Mountains
The High Peaks and most of the. central Adirondacks are made up of anorthosite and
charnocMtip gneiss, both of which are low iri uranium and unlikely to cause radon problems. The
rim of the Adirondacks are predominantly metasedimentary and metavolcanic rocks noted for base
metal deposits, several of which have known local uranium occurrences and have locally high
radon potential. The iron deposits in eastern Essex County between Crown Point and Westport are
locally enriched in uranium, as are granitic and syenitic gneiss in Clinton County and granitic
gneiss and pegmatite at the Benson Mines in St. Lawrence County (McKeown and Klemic, 1953).
Laymon and others (1990) note that mine tailings from the Essex County deposits contain as much
as 204 ppm of uranium and that building blocks for local homes were made from this material, but
they do not indicate whether high radon was found in these homes. Four uranium occurrences
have also been identified in Lewis County associated with magnetite and sulfide deposits in granitic
gneiss, pegmatite, and amphibolite (Grauch and Zarinski, 1976).
Equivalent uranium (fig. 7) in the Adirondacks is low over the High Peaks and
surrounding charnocMtic rocks. Moderate and locally high equivalent uranium is associated with
the Northwest Lowlands and scattered areas in metasedimentary rocks and iron deposits in the
southeastern and eastern rim of the Adirondacks. Soils have low to moderate permeability with
locally high permeability in sand and gravelly glacial deposits. Most counties in the Adirondack
Mountains have geometric means of indoor radon less than 2 pCi/L. Average Indoor radon is < 1.5
pCi/L in Essex, Hamilton, and Franklin Counties, but greater than 2 pC/L for Herkimer, Warren,
St Lawrence, and Lewis Counties. These counties also lie partially in other geologic provinces.
Laymon and others (1990) have ranked the Adirondacks low in radon potential, with the uranium
occurrence areas having locally high radon potential. We rank the High Peaks and Adirondacks
low in radon potential but rank the Northwest Lowlands moderate in radon potential due to the .
high radioactivity, local occurrence of uranium, local glacial gravel deposits, the sheared and -
faulted metamorphic rocks, and higher indoor radon in St. Lawrence County.
Valley and Ridge ,.',•'• .
In the Valley and Ridge section, sedimentary rocks of Cambrian through Ordovician age
comprise the underlying bedrock and have been,ranked high in radon potential but can be locally
low to moderate. Cambrian and Ordovician rocks are a marine shelf sequence with basal Cambrian
sandstones and conglomerates followed by a highly variable sequence of interbedded shales and
limestones. Recent studies of indoor radon and soil radon in Orange County by J. Driscoll and
A.E. Gates of Rutgers University and L.C.S. Gundersen of the U.S. Geological Survey
(unpublished data) indicate that many of the black shales in this sequence are elevated in uranium
(>2 ppm) and, although the limestones are relatively low in uranium, the local residual soils they •
form in the valleys of the area are elevated in uranium. The studies also indicate that indoor radon
(3 month alpha-track) is elevated (> 4 pCi/L) in basements of homes built in limestone soils of the
Wallkill Valley, in black shale bedrock, and especially in glacial gravel deposits of black shales.
Equivalent uranium (fig. 7) is moderate to high in the Valley and Ridge. Indoor radon in Orange
County (Table 1) averages 4.5 pCi/L and the geometric mean is 2.4 pCi/L.
The Triassic Lowland
The Triassic Lowland is underlain by fluvial quartz sands, minor siltstories and shales, and
Jurassic basalt and diabase, and underlies most of Rockland County. Of these rock types, the
shales have the potential to be a source of radon problems; however, they are not abundant There
IV-37 Reprinted from USGS Open-File Report 93-292-B
-------
are no uranium occurrences reported in the Newark Supergroup of New York. Black shales and
gray sandstones in the lower Passaic Formation are similar to uranium-bearing units in the same
formation in New Jersey, but they make up a minor part of the section. Rockland County has a
basement indoor radon average of 2.2 pCi/L and a geometric mean of 1.3 pCi/L. Equivalent
uranium (fig. 7) is low to moderate in the Triassic Lowlands. Soil permeability is generally low to
moderate. The Triassic Lowlands have been ranked low in radon potential. .
Atlantic Coastal Plain
Long Island, in the Atlantic Coastal Plain Province, is made up of glacial deposits and
marine sediments with little or no known uranium concentrations. Indoor radon measurements are
among the lowest in the State. Counties of the Atlantic Coastal Plain have indoor radon geometric
means less than 2 pCi/L and average concentrations of indoor radon less than 2 pCi/L.
Permeability is moderate to high with local areas of low permeability. Laymon and others (1990)
ranked the Atlantic Coastal Plain as low in radon potential because of the low radium content of the
soils; however, they did note that a number of boulders in the moraines have high levels of
radioactivity and coarse gravels and sands of the glacial outwash may also have isolated uranium
concentrations making them local sources of high radon.
SUMMARY
For the purpose of this assessment, New York has been divided into ten geologic radon
potential areas and each area assigned a Radon Index (RI) and a Confidence Index (CI) score
(Table 5). The RI is a relative measure of radon potential based on geology, soils, radioactivity,
architecture, and indoor radon. The CI is a measure of the relative 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 booklet for more information). The radon potential areas are
shown in figure 11.
Indoor radon data for New York, when compared with geology, indicate that certain
surficial deposits and rocks of the Allegheny Plateau, Hudson Highlands, Taconic Mountains and
Valley and Ridge Provinces have the potential to produce high levels of indoor radon (> 4 pCi/L).
Surficial deposits and rocks of the-Hudson-Mohawk Lowland, Erie-Ontario Lowlands, the
Champlain and St. Lawrence Lowlands, and the Northwest Lowlands of the Adirondacks are
generally more moderate in radon potential but may be locally high where glacial deposits are
highly permeable. Surficial deposits and rocks of the Adirondacks, the Triassic Lowlands,
Manhattan Prong, and the Atlantic Coastal Plain are relatively low in radon potential.
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 that assigned to the area as a whole. Any local decisions about radon should
not 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.
IV-38 Reprinted from USGS Open-File Report 93-292-B
-------
TABLE 5. RI and CI scores for geologic radon potential areas of New York.
St. Lawrence-Champlain
Lowland
FACTOR RI CI
INDOORRADON
RADIOACTIVITY
GEOLOGY
SOIL PERM.
ARCHITECTURE
. GFE POINTS
TOTAL
2
1
>2
1
3
o
9
2
2
3
3
10
Erie-Ontario ;; Hudson-Mohawk , Allegheny
Lowland Lowland/Northwest Lowlands Plateau
RI CI RI CI RI CI
2
1
2
1
• 3
0
9
2
2
3
3
10
2
2
2
2
3
0
11
2
2
3
^ 3
10
2
2
3
2
3
0
12
2
2
3
3
10
Mod High
Mod High
Mod High
Taconic Mts.-
.' ' New England Upland
FACTOR RI CI
INDOOR RADON
RADIOACTIVITY
GEOLOGY
SOIL PERM.
ARCHITECTURE
GFE POINTS
TOTAL
3
2
2
.2
3
0
12
2
2
2
3
9
Manhattan
Prong
RI CI
1
1
2
2
2
0
8
2
2
2
3
9
Hudson •'
Highlands
RI CI
2
2
2
2
3
, '2
13
2
2
3
. 3
10
Adirondack Mountains
• High Peaks
RI CI
1
1
1
2
3 ,
0
8 .
2
2
3
3
10
High Mod
Low Mod
High High
Low. High
FACTOR
INDOOR RADON
RADIOACTIVITY
GEOLOGY
SOIL PERM.
ARCHITECTURE
GFE POINTS
Valley
RT
3
2
2
2
3
0
and Ridge
CI
2
2
3
3
Triassic Lowland
RI a
i
i
i
2
. 3
0
2
2
:3
3 '
Atlantic Coastal Plain
-RI -CI
1
1
1
2
2
0
2
1
3
3
TOTAL
12
10
High High
Low
10
High
Low
Mod
RADON INDEX SCORING:
Radon potential category
Point range
Probable screening indoor
radon average for area
LOW 3-8 points <2pCi/L
MODERATE/VARIABLE 9-11 points 2 - 4 pCi/L
HIGH - >lipoints >4pCi/L
Possible range of points = 3 to 17
CONFIDENCE INDEX SCORING:
LOW CONFIDENCE
MODERATE CONFIDENCE
HIGH CONFIDENCE
4-6 points
7-9 points
10-12 points
Possible range of points = 4 to 12
IV-39 Reprinted from USGS Open-FUe Report 93-292-B
-------
> /• «*; '. f i ^<~'// i :^x—-v>~
5» • S;1/ ' ' S W-?-^
r-.'^V? " .X \/ =bgy
-------
Table 6. Geologic radon potential and screening indoor radon averages for counties in New
York. "Dominant Geologic Province" indicates the geologic province occupied by all or most of
the county. A * indicates counties located in 2 or more provinces with different geologic radon
potential. An # indicates counties in which the geologic radon potential ranking differs from the
rank based on screening indoor radon average. The variability of the geology in these counties
affects the indoor radon levels and more detailed information from state and local officials
should be used when assessing these areas. .
COUNTY
Albany
Allegany
Broome
Cattaraugus
Cayuga
Chautauqua
Chemung
Cheriango
Clinton
Columbia
Cortland
Delaware
Dutchess
Erie
Essex
Franklin
Fulton
Genesee
Greene
Hamilton
Herkimer
Jefferson
Lewis
Livingston
Madison
Monroe
Montgomery
Nassau
Niagara
Qneida
Onondaga
Ontario
Orange
Orleans
Oswego
Otsego
Putnam
Rensselaer
Rockland
St. Lawrence
Saratoga
Schenectady
Schoharie
Schuyler
DOMINANT GEOLOGIC
PROVINCE
Hudson-Mohawk Lowland *
Allegheny Plateau
Allegheny Plateau
Allegheny Plateau
Allegheny Plateau *
Allegheny Plateau ,
Allegheny Plateau
Allegheny Plateau
St. Lawrence-Champlain Lowland *
New England Upland-Taconics
Allegheny Plateau
Allegheny Plateau
New England Upland-Taconics
Allegheny Plateau *
Adirondacks
St. Lawrence-Champlain Lowland *
Adirondacks *
Allegheny Plateau *
Allegheny Plateau *
Adirondacks
Adirondacks *
Erie-Ontario Lowland *
Tug Hill Plateau*
Allegheny Plateau *
Allegheny Plateau *
Erie-Ontario Lowland *
Hudson-Mohawk Lowland
Coastal Plain
Erie-Ontario Lowland
Erie-Ontario Lowland *
Allegheny Plateau *
Allegheny Plateau *
Valley and Ridge *
Erie-Ontario Lowland
Erie-Ontario Lowland *
Allegheny Plateau
Hudson Highlands *
New England Upland-Taconics
Triassic Lowland *
St. Lawrence-Champlain Lowland *
Hudson-Mohawk Lowland *
Hudson-Mohawk Lowland
Allegheny Plateau *
Allegheny Plateau
GEOL. RADON
POTENTIAL
MODERATE
HIGH
HIGH
HIGH
HIGH
HIGH
fflGHJ
HIGH
MODERATE
HIGH
HIGH
HIGH
HIGH
HIGH
LOW
LOW
LOW* •
HIGH
HIGH
LOW .
LOW*
MODERATE
MODERATE*
HIGH
HIGH
MODERATE
MODERATE
LOW
MODERATE*
MODERATE*
HIGH
HIGH
HIGH
MODERATE ,
MODERATE
HIGH .
HIGH* .
HIGH -
LOW*
MODERATE
MODERATE
MODERATE
HIGH
HIGH*
INDOOR Rn
RANK (EPA)
MODERATE
HIGH
HIGH
HIGH
HIGH
HIGH
HIGH
HIGH
MODERATE
HIGH
HIGH
HIGH
HIGH
HIGH
LOW
LOW
MODERATE
HIGH
HIGH
LOW
HIGH
MODERATE
HIGH
HIGH
HIGH -
MODERATE
MODERATE
LOW ,
LOW
•- HIGH
HIGH
HIGH
HIGH
MODERATE
MODERATE
HIGH
MODERATE
HIGH
MODERATE
MODERATE
MODERATE
MODERATE
HIGH
MODERATE
INDOOR Rn
AVERAGE
3.7
10.2
5.7
6.5
' 4.4
5.3 t
12.4
8.5
2.2
,7.0
14.2 ,
, 7.0
6.3 ,
4.4
115
1.3
2.1
7.7
• 4.4
1.6
4.6
3:0
4.4
6.2
4.8
2.8
3.6
1.2
1.7
5.1
8.5
. 5.3
4.5
3.2
2.0
8.0
; 4.0
6.4
2.2
2.3
3.2 .
3.0
, 5.4
4.0
-------
Table 6 (continued).
COUNTY
Seneca
Steuben
Suffolk
Sullivan
Tioga
Tompkins
Ulster
Warren
Washington
Wayne
Westchester
Wyoming
Yates
New York City
DOMINANT GEOLOGIC
PROVINCE
Allegheny Plateau *
Allegheny Plateau
Coastal Plain
Allegheny Plateau
Allegheny Plateau
Allegheny Plateau
Allegheny Plateau *
Adirondacks *
New England Upland-Taconics *
Erie-Ontario Lowland
Manhattan Prong *
Allegheny Plateau
Allegheny Plateau
Coastal Plain
GEOL. RADON
POTENTIAL
fflGH#
HIGH
LOW
fflGH#
HIGH
HIGH
HIGH*
LOW#
HIGH
MODERATE
LOW#
HIGH
HIGH
LOW
INDOOR Rn
RANK (EPA)
MODERATE
HIGH
LOW
MODERATE
HIGH
HIGH
MODERATE
MODERATE
HIGH
MODERATE
MODERATE
HIGH
HIGH
LOW
INDOOR Rn
AVERAGE
2.5
11.2
1.6
3.1
8.3
4.4
4.0
2.1
> 4.7
3.8
2.4 ..
8.9
5.8
1.4
-------
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Weiner, R.W., McLelland, J.M., Isachsen, Y.W., and Hall, L.M., 1984, Stratigraphy and
structural geology of the Adirondack Mountains, New York: Review and synthesis, in
Bartholomew, M.J., The Grenville Event in the Appalachians and related topics:
Geological Society of America Special Paper, 194, p. 1-56.
IV-48 Reprinted from USGS Open-File Report 93-292-B
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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 pf its area lies. (See Part I for more
details!) , . . - ,
NEW YORK MAP OF RADON ZONES
The New York Map of Radon Zones and its supporting documentation (Part IV of this-
report); have received extensive review by New York geologists and radon program experts.
The map for New York 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.
Although the information provided in Part IV of this report ~ the State chapter entitled
"Preliminary Geologic Radon Potential Assessment of New York" -- 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 2 EPA office or the
New York radon program for information on testing and fixing homes. Telephone numbers
and addresses can be found in Part II of this report.
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