United States
           Environmental Protection
           Agency
Air and Radiation
(6604J)
4O2-R-93-04S
September 1993
4>EPA    EPA's Map of Radon Zones

           NEW HAMPSHIRE

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       EPA'S MAP OF RADON ZONES
            NEW HAMPSHIRE
             RADON DIVISION
  OFFICE OF RADIATION AND INDOOR AIR
U.S. ENVIRONMENTAL PROTECTION AGENCY
             SEPTEMBER, 1993

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                             ACKNOWLEDGEMENTS
      This document was prepared by the U.S. Environmental Protection Agency's (EPA's)
Office of Radiation and Indoor Air (ORIA) in conjunction with the U.S. Geological Survey
(USGS).  Sharon W. White was the EPA project manager. Numerous other people in ORIA
were instrumental in the development of the Map of Radon Zones, including Lisa Ratcliff,
Kirk Maconaughey, R. Thomas Peake, Dave Rowson, and Steve Page.

      EPA would especially like to acknowledge the outstanding effort of the USGS
radon team — Linda Gundersen, Randy  Schumann, Jim Otton, Doug Owen, Russell
Dubiel, Kendell Dickinson, and Sandra Szarzi — in developing the technical base for the
Map of Radon Zones.

      ORIA  would also like to recognize  the efforts of all the EPA Regional Offices in
coordinating the reviews with the State programs  and the  Association of American State
Geologists (AASG) for  providing a liaison with the State  geological surveys.  In  addition,
appreciation is expressed to all of the State radon programs and geological surveys for their
technical  input and review of the Map of Radon Zones.

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           TABLE OF CONTENTS
              I. OVERVIEW
    II. THE USGS/EPA RADON POTENTIAL
        ASSESSMENTSiINTRODUCTION
  III. REGION 1 GEOLOGIC RADON POTENTIAL
                SUMMARY
V. PRELIMINARY GEOLOGIC RADON POTENTIAL
      ASSESSMENT OF NEW HAMPSHIRE
      V. EPA'S MAP OF RADON ZONES --
             NEW HAMPSHIRE

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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 years to produce  a series of maps and
documents which address-these directives. The EPA Map of Radon  Zones is a compilation of
that work  and fulfills the requirements of sections 307 and 309 of IRAA.  The Map of Radon
Zones identifies, on a county-by-county basis, areas of the  U.S. that  have the highest potential
for elevated indoor radon levels (greater than 4 pCi/L).
       The Map of Radon Zones is  designed to assist national, State and local governments
and organizations to target their radon program activities and resources. It is also intended to
help building code officials determine areas that are the highest priority for adopting radon-
resistant building practices. The Map of Radon Zones should not be used to  determine if
individual homes in any given area need to be  tested for radon.  EPA recommends that all
homes be tested for radon, regardless  of geographic location or the zone  designation of
the county in which they are located.
       This document provides background information concerning the development of the
Map of Radon Zones.  It explains the purposes of the map, the approach for developing the
map (including the respective roles of EPA and USGS), the data sources used, the conclusions
and confidence levels developed for the prediction of radon potential, and the review process
that was conducted to finalize this effort.

BACKGROUND

       Radon (Rn222) is a colorless,  odorless, radioactive gas.  It comes from  the natural
decay of uranium that is found in nearly all soils.  It typically moves through the ground to
the air above and into homes and other buildings through cracks  and openings in the
foundation.  Any home, school or workplace may have a radon problem, regardless of
whether it is new or old, well-sealed or drafty, or with or. without a  basement.  Nearly one out
of every 15 homes in the U.S. is estimated to have elevated annual average levels of indoor
radon.
       Radon first gained national attention in  early 1984, when  extremely high levels of
indoor radon were found in areas of Pennsylvania, New Jersey, and  New York, along the
Reading Prong-physiographic province.  EPA established a Radon Program in 1985 to assist
States and homeowners in reducing  their risk of lung cancer from indoor radon.
       Since 1985, EPA and USGS have been working together to continually increase our
understanding of radon sources and  the migration dynamics that cause elevated indoor radon
levels.  Early efforts resulted in the  1987 map  entitled "Areas with Potentially High Radon
Levels."  This map was based on  limited geologic information only  because few indoor radon
measurements were available at the  time.  The development of EPA's Map of Radon Zones
and  its  technical foundation, USGS1 National Geologic Radon Province Map, has been based
on additional information from six years of the State/EPA Residential  Radon Surveys,
independent  State residential  surveys, and continued expansion of geologic and geophysical
information, particularly the data from the National Uranium Resource Evaluation project.
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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 I 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
rssianTd to each contributing variable.  The approach used by USGS to estimate the radon
potential for  each province is described in Part II of this document.
       EPA subsequently developed the  Map of Radon Zones by extrapolating  from the
province level to the county  level so that all counties in the  U.S. were assigned to one of
three radon'zones.  EPA assigned each county to a given zone based on its provincial radon
potential. For example, if a  county is  located withm 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 g.ven 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 m  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 spec.f.c w.thm-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 "'"door radon
  data geology, aerial radioactivity, soils, and foundation type - are basm 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  > factors at the
  county level.  In order to validate the map in light of this  lack of statistical confidence, EPA
  conducted  a number of analyses.  These analyses have helped EPA to identify the best
  situations in which  to apply the map, and its limitations.
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Figure 3
                 Geologic  Radon Potential  Provinces  for  Nebraska
         Lincoln C o u.n t y
                    Uoicritr      Low
Figure 4
         NEBRASKA  -  EPA Map  of  Radon  Zones
        Lincoln County
         last I     Zoac 2    Zone 3
                                       1-6

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       One such analysis involved comparing county zone designations to indoor radon
measurements from the State/EPA Residential Radon Surveys (SRRS). Screening  averages
for counties with at least 100 measurements were compared to the counties' predicted radon
^ " -dfcated by the Map  of Radln Zone,  EPA found that 72% of the county
screening averages were correctly reflected by the appropriate zone delations on the Map.
In all other cases, they only differed by 1 zone.
       Another accuracy analysis used the annuaLaverage 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  participate,:I in the survey, their
radon measurements,  and the zone designations  for these  counties EPA found that
approximately 3.8 million homes of the 5.4 million homes with radon levels greater than or
equal to 4  pCi/L will be found in counties designated as Zone  1.  A random sampling of an
equal number of counties would have only found approximately  1.8 rmlhon homes greater
than 4 PCi/L  In other words, this analysis indicated that the map approach is three times
more efficient at identifying high radon areas than random selection of zone designations.
       Together, these analyses show that the approach EPA used to develop the Map of
Radon Zones is a reasonable one.  In addition, the Agency's confidence is enhanced by  results
of the extensive State review process - the map generally agrees with the States knowledge
of and experience in  their own jurisdictions.  However, the accuracy analyses highlight  two
 important  points:  the fact that elevated levels will be found in Zones 2 and 3  andI 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 he
 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 the,.- homes
  for radon, regardless of geographic location or the zone designation of the county m
  which  they live.  Similarly, the Map of Radon Zones should not to  be used in  heu of
  testing during real estate transactions.
  Review Process
         The Map of Radon Zones has undergone extensive review within EPA and outside the
  Agency  The Association of American State Geologists (AASG) played an integral role in
  this review process.  The AASG individual State geologists have reviewed their State-specific
  information, the USGS Geologic Radon Province Map, and other materials for their geologic
  content and consistency.
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       In addition to each State geologist providing technical comments, the State radon
offices were asked to comment on their respective States' radon potential evaluations.  In
particular, the States were asked to evaluate the data used to assign their counties to specific
zones.  EPA and USGS worked with the States to resolve any issues concerning county zone
designations.   In a few cases, States have requested  changes in county zone designations.  The
requests were based on additional data from the State on geology, indoor radon
measurements, population, etc.  Upon reviewing the data submitted by the  States, EPA did
make some changes in zone designations.  These changes, which do not strictly follow the
methodology outlined in this document, are discussed in the respective State chapters.
       EPA encourages the  States and counties to conduct further research and data collection
efforts to refine the Map of Radon Zones.   EPA would like to be kept informed of any
changes the States, counties, or others make to the maps.  Updates and revisions will be
handled in a similar fashion to the way the map was developed.  States should notify EPA of
any proposed changes by forwarding the changes  through the Regional EPA offices that are
listed in Part II.  Depending on the amount of new information  that is presented, EPA will
consider  updating this map periodically. The State radon programs should initiate proper
notification of the appropriate  State officials when the Map of Radon Zones is released and
when revisions or updates are made by the State or  EPA.
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    THE USGS/EPA RADON POTENTIAL ASSESSMENTS: AN INTRODUCTION
                                           by    ••
                     Linda C.S. Gundersen and R. Randall Schumann
                                  U.S. Geological Survey
                                           and
                                    Sharon W. White
                           U.S. Environmental Protection Agency

BACKGROUND

    The Indoor Radon Abatement Act of 1988 (15 U.S.C. 2661-2671) directed the U.S.
Environmental Protection Agency (EPA) to  identify  areas of the United States that have the
potential to produce harmful levels of indoor radon.  These characterizations were to be based
on both geological data and on indoor radon levels in homes and other structures.  The EPA
also was directed to develop model standards and techniques for new building construction
that would provide adequate prevention or mitigation of radon entry.  As part  of an
Interagency Agreement between the EPA and the U.S. Geological Survey (USGS), the USGS
has prepared  radon potential estimates for the United States. This report is one of ten
booklets that document this effort.  The purpose and intended use of these reports is to help
identify areas where states  can target  their radon program resources, to provide guidance in
selecting the  most appropriate building code options for areas, and to provide  general
information on radon and geology for each  state for federal, state, and municipal officials
dealing with  radon issues.  These reports are not intended to be used as a substitute for
indoor radon testing,  and they cannot and should not be used to  estimate or predict the
indoor radon concentrations of individual homes, building sites, or  housing tracts.  Elevated
levels of indoor radon have been found in every State, and EPA recommends that all homes
be  tested for indoor radon.
     Booklets detailing the radon  potential assessment for the U.S. have been developed for
each State.  USGS geologists  are the  authors of the geologic radon  potential booklets.  Each
booklet consists of several components, the  first being an overview to the mapping project
(Part I), this  introduction to the USGS assessment (Part II), including a general discussion of
radon (occurrence, transport, etc.), and details concerning the types of data used. The  third
component is a summary chapter outlining  the general geology and geologic radon potential
of  the EPA Region (Part III).  The fourth component is an individual chapter for each state
(Part IV).  Each state chapter discusses the  state's specific geographic setting,  soils, geologic
setting, geologic radon potential, indoor radon data, and a summary outlining  the radon
potential rankings of geologic areas in the state.  A variety  of maps are presented in each
chapter—geologic, geographic, population,  soils, aerial radioactivity, and indoor radon data by
county.  Finally, the  booklets contain EPA's map of radon zones for each state and an
accompanying description  (Part V).
     Because of constraints on the scales of maps presented in these reports and because  the
smallest units used to present the indoor radon data are counties, some generalizations have
 been  made  in order to estimate the radon potential of each area. Variations  in geol^>, soil
 characteristics, climatic factors, homeowner lifestyles, and other  factors that influence radon
 concentrations can be quite large within any particular geologic  area, so these reports  cannot
 be used to estimate or  predict the indoor radon  concentrations of individual homes or housing

                                           II-1     Reprinted from USGS Open-File Report 93-292

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 tracts.  Within any area of a given geologic radon potential ranking, there are likely to be
 areas where the radon potential is lower or higher than that assigned to the area as a whole,
 especially in larger areas such as the large counties  in some western states.
     In each state chapter, references to additional reports related to radon are listed for the
 state, and the reader is urged to consult these reports for more detailed information.  In  most
 cases the best sources of information oh 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 (238U) (fig. 1).  The half-life of :~Rn is 3.825 days. Other
 isotopes of radon occur naturally, but, with the exception of thoron (2-°Rn), which occurs in
 concentrations high enough to be of concern in a few localized areas, they are less important
 in'terms of indoor radon risk because of their extremely short half-lives and less common
 occurrence.  In general, the concentration and mobility of radon in soil are dependent on
 several  factors, the most important of which are the soil's radium content and distribution,
 porosity, permeability to gas movement, and moisture content.  These characteristics are, in
 turn, determined by the soil's parent-material composition, climate, and the soil's age or
 maturity.  If parent-material composition,  climate, vegetation, age of the soil, and topography
 are known, the physical and  chemical properties of a soil in a given area can be predicted.
     As soils form, they develop distinct layers, or horizons, that are cumulatively called the
 soil profile.  The A horizon is a surface or near-surface horizon containing a relative
 abundance of organic matter but dominated by mineral matter.  Some soils contain an E
 horizon, directly below the A horizon, that is generally characterized by loss of clays, iron, or
. aluminum, and has a characteristically lighter color than the A  horizon.  The B horizon
 underlies the A or E horizon. Important characteristics of B horizons include accumulation of
 clays, iron oxides, calcium carbonate or other soluble salts, and organic matter complexes.  In
 drier environments, a horizon may exist within or below the B horizon that is dominated by
 calcium carbonate, often called caliche or calcrete. This carbonate-cemented horizon is
 designated the K  horizon  in modern soil classification schemes.  The C horizon underlies the
 B (or K) and is a zone of weathered parent material that does not exhibit characteristics of A
 or B horizons; that is, it is generally not a zone of leaching or accumulation.  In soils formed
 in place from the underlying bedrock, the C  horizon is a zone of unconsolidated, weathered
 bedrock overlying the unweathered bedrock.
     The shape and orientation of soil  particles (soil structure) control permeability  and affect
 water movement in the soil.  Soils with blocky or granular structure have roughly equivalent
 permeabilities  in the horizontal and vertical directions, and air and  water can infiltrate the soil
 relatively easily.  However, in soils with platy structure, horizontal permeability is much
 greater than vertical permeability, and air  and moisture infiltration  is generally slow.  Soils
 with prismatic or columnar structure have dominantly  vertical permeability.  Platy  and
 prismatic structures form in soils with high clay contents.  In soils  with shrink-swell clays,  air


                                            II-2     Reprinted from USGS Open-File Report 93-292

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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 chrinkage 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 air moves through soil pores in response to differences  in pressure
within the soil or between the soil and the atmosphere, carrying the radon atoms along with it,
Diffusion is the dominant radon transport process in soils of  low permeability, whereas flow
tends to  dominate in highly permeable soils (Sextro and others, 1987).   In low-permeability
soils, much of the radon may decay before it is able to enter  a building because its transport
rate is reduced.  Conversely, highly permeable soils, even those that are relatively low in
radium, such as those derived from some types of glacial deposits, have been associated with
high indoor radon levels in Europe and in the northern United States (Akerblom  and others,
1984; Kunz and others, 1989; Sextro and others, 1987).  In areas of karst topography  formed
in carbonate rock (limestone or dolomite) environments, solution cavities and fissures  can
increase  soil permeability at depth by providing additional pathways for gas flow.
    Not  all radium  contained in soil  grains and grain coatings will result in mobile radon
when the radium decays. Depending on where the radium is  distributed in  the soil, many of
the radon atoms may remain imbedded in the soil grain containing the  parent radium atom, or
become imbedded in adjacent soil grains.  The portion of radium that releases radon into the
pores and fractures  of rocks and soils is called the emanating fraction.  When a radium atom
decays to radon, the energy  generated is strong enough to send the radon atom a distance of
about 40 nanometers (1 nm  = 10'9 meters), or about 2xlO'c> inches—this  is known  as alpha
recoil (Tanner, 1980).  Moisture in the soil lessens the chance of a recoiling radon atom
becoming imbedded in an adjacent grain.  Because water is more dense than air, a radon atom
will  travel a shorter distance in a water-filled pore than in an air-filled  pore, thus  increasing
the likelihood  that the radon atom will remain in the pore space. Intermediate moisture levels
enhance'radon emanation but do not significantly affect permeability.  However, high
moisture levels can significantly decrease the gas permeability of the soil and impede  radon
movement through  the soil.
    Concentrations  of radon in soils are generally many  times higher than those inside of
buildings, ranging from tens of pCi/L to more than  100,000 pCi/L, but typically in the range
of hundreds to low thousands of pCi/L.  Soil-gas radon concentrations can vary in response to
variations in climate and weather on hourly, daily, or seasonal time scales.  Schumann and
others (1992) and Rose and others (1988) recorded order-of-magnitude variations  in soil-gas •
radon concentrations between seasons in Colorado  and Pennsylvania. The most important
factors appear to be (1) soil moisture conditions, which are controlled in large part by
precipitation; (2) barometric pressure; and (3) temperature.  Washington and Rose (1990)
suggest that temperature-controlled partitioning of radon between water and gas in soil pores
also has  a significant influence on the amount of mobile radon in  soil  gas.
    Homes in  hilly  limestone regions of the southern Appalachians were found to have higher
indoor radon concentrations during the summer than in the winter.   A suggested cause for this
phenomenon involves temperature/pressure-driven flow of radon-laden air from subsurface


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solution cavities in the carbonate rock into houses.  As warm air enters solution cavities that
are higher on the hillslope than the homes, it cools  and settles, pushing radon-laden 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 driving force (reduced atmospheric pressure  in the house relative to the soil, producing
a pressure gradient) and entry points must exist for radon to enter a building from the soil.
The negative pressure caused by furnace combustion, ventilation devices, and  the stack effect
(the rising and escape of warm air from  the upper floors of the building, causing a
temperature and pressure gradient within the structure) during cold winter months are
common driving forces.  Cracks and other penetrations through building foundations, sump
holes  and slab-to-foundation wall joints are common entry  points.
    Radon levels in the basement are generally higher than  those on the main floor or 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
 soiUadioactivity were not  used except where such data  were available  in existing, published
 reports of local field studies.  Where applicable, such field studies are described in the
 individual state chapters.

 GEOLOGIC DATA

     The types and distribution  of lithologic  units and other geologic features in an
 assessment area are of primary importance in determining  radon potential.  Rock types that
 are most likely to cause indoor radon problems  include carbonaceous black shales, glaucomte-
 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 contact metamorphosed rocks.
 Rock types least likely  to cause radon problems include marine quartz sands, non-
 carbonaceous shales and siltstones, certain kinds of clays, silica-poor metamorphic and

                                            II-5     Reprinted from USGS Open-File Report 93-292

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 igneous rocks, and basalts.  Exceptions exist within these general lithologic groups because of
 the occurrence of localized uranium deposits, commonly of the hydrothermal type in
 crystalline rocks or the "roll-front"  type in sedimentary rocks.  Uranium and radium are
 commonly sited in heavy minerals,  iron-oxide coatings on rock and soil grains, and organic
 materials  in soils and'sediments.  Less common are uranium associated with phosphate and
 carbonate complexes in rocks and soils, and uranium minerals.
    Although many  cases of elevated indoor radon levels can be traced to high radium and
 (or) uranium concentrations in parent rocks, some structural  features, most notably  faults and
 shear zones, have been identified as sites of localized uranium concentrations (Deffeyes and
 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 (^Bi), with the assumption that uranium and
 its decay products are  in secular equilibrium. Equivalent uranium is expressed in units of
 parts per million (ppm).  Gamma radioactivity also may be expressed in terms of a radium
 activity; 3 ppm eU corresponds to approximately 1 picocurie per gram (pCi/g) of radium-226.
 Although  radon is highly mobile in  soil and its concentration is affected by meteorological
 conditions (Kovach,  1945; Klusman and Jaacks, 1987; Schery and others, 1984; Schumann
 and others, 1992), statistical correlations between average soil-gas radon concentrations and
 average eU values for  a wide variety of soils have been  documented (Gundersen and others,
 1988a, 1988b; Schumann and Owen, 1988). Aerial radiometric data can provide an estimate
of radon source strength over a region, but the amount of radon that is able to enter a home
 from the soil is dependent on several local factors, including soil structure, grain size
 distribution, moisture content, and permeability, as well as type of house construction and its
structural  condition.
    The aerial radiometric data used for these characterizations were collected as part 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-fay  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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                 FUCUT LINE  SPACING OF  NUKE  AERIAL  SURVEYS
                     2 k'U  (i  MILE]
                     5 l]i  (3  MILES]
                     2 fc 5  KM
                     10 KM  (6 UILES)
                     5 t 10  EH
                     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.

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    Figure 2 is an index map of NURE  1° x 2° quadrangles showing the flight-line spacing
for each quadrangle.  In general, the more closely spaced the flightlines are, the more area
was covered by the aerial gamma survey, and thus, more detail is available in the data set.
For an altitude of 400 ft above the ground surface and with primary flightline spacing
typically between 3 and 6 miles, less than 10 percent of the ground surface of the United
States was actually measured by the airborne gamma-ray detectors (Duval and others, 1989),
although some areas had better coverage than others due to the differences in flight-line
spacing between areas (fig.  2).  This suggests that some  localized uranium anomalies may not
have  been detected by the aerial surveys, but the good correlations of eU patterns with
geologic outcrop patterns indicate that, at relatively small scales (approximately 1:1,000,000
or smaller) the National eU map (Duval and others, 1989) gives reasonably good estimates of
average surface uranium concentrations and thus can assist in the  prediction of radon potential
of rocks and soils, especially when augmented with additional geologic and soil data.
    The shallow (20-30 cm) depth of investigation of gamma-ray spectrometers, either
ground-based or  airborne (Duval and others, 1971; Durrance, 1986), suggests that gamma-ray
data may  sometimes underestimate the radon-source strength in soils in which some of the
radionuclides in the near-surface soil  layers have been transported downward through the soil
profile.  In such cases the concentration of radioactive minerals in the A horizon would be
lower than in the B horizon, where such minerals are typically concentrated. The
concentration of radionuclides in the C horizon and below may be relatively unaffected by
surface  solution processes.   Under these conditions the surface gamma-ray signal may indicate
a lower radon source concentration than  actually exists in the deeper soil layers, which are
most  likely to affect radon levels in structures with basements.  The redistribution of
radionuclides in soil profiles is dependent on a combination of climatic, geologic,  and
geochemical  factors.  There is reason to believe that correlations of eU with  actual soil
radium  and uranium concentrations at  a depth relevant to radon entry into structures may be
regionally variable (Duval,  1989; Schumann  and Gundersen, 1991). Given sufficient
understanding of the factors cited  above, these  regional differences may be predictable.

SOIL  SURVEY DATA

    Soil surveys  prepared by the U.S.  Soil Conservation Service (SCS) provide  data on soil
characteristics,  including soil-cover thickness, grain-size  distribution, permeability, shrink-
swell  potential, vegetative cover, generalized groundwater characteristics, and land use. The
reports are available in county formats and State summaries.  The county reports typically
contain  both  generalized and detailed maps of soils in  the area.
    Because  of time and map-scale constraints, it was  impractical to examine county soil
reports for each county in the United States, so more generalized summaries at appropriate
scales were used where available.  For State or regional-scale radon characterizations, soil
maps  were compared to geologic maps of the area, and the soil descriptions, shrink-swell
potential,  drainage characteristics, depth to seasonal high water table, permeability, and other
relevant characteristics of each soil group noted. Technical soil terms used in soil surveys are
generally  complex; however, a good summary  of soil engineering terms and the national
distribution of technical soil types is the "Soils" sheet of the National Atlas (U.S. Department
of Agriculture, 1987).
                                           II-8      Reprinted from USGS Open-File Report 93-292

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    Soil permeability is commonly expressed in SCS soil surveys in terms of the speed, in
inches per hour (in/hr), at which water soaks into the soil, as measured in a soil percolation
test.  Although in/hr are not truly units of permeability, these units are in widespread use and
are referred to as "permeability"  in SCS  soil surveys.  The permeabilities listed in the SCS
surveys are for water, but they generally correlate well with gas permeability.  Because data
on gas permeability of soils is extremely limited, data on permeability to water is used as a
substitute except in cases in which excessive soil moisture is  known to  exist.  Water in soil
pores inhibits gas transport, so the amount of radon available to a home is effectively reduced
by a high water table.  Areas likely to have high water tables include  river valleys, coastal
areas, and some areas overlain by deposits of glacial origin (for example, loess).
    Soil permeabilities greater than 6.0 in/hr may be considered high, and permeabilities less
than 0.6 in/hr may  be considered low in terms of soil-gas transport. Soils with low
permeability may generally be considered to have a lower radon potential than more
permeable soils with similar radium concentrations.  Many well-developed soils contain a
clay-rich B horizon that may  impede vertical soil gas transport.  Radon  generated below this
horizon cannot readily escape to the surface, so it would  instead tend  to move laterally,
especially under the influence of a negative pressure exerted by.a building.
    Shrink-swell potential is an indicator of the abundance of smectitic  (swelling) clays in a
soil.  Soils  with a high shrink-swell potential may  cause building foundations to crack,
creating pathways  for radon entry into the structure.  During dry periods, desiccation cracks in
shrink-swell soils provide additional pathways  for soil-gas transport and effectively  increase
the gas permeability of the soil:   Soil permeability data and soil  profile  data thus provide
important information for regional radon assessments.

INDOOR RADON DATA

    Two major sources  of indoor radon data were  used.  The first and largest source of data is
 from the State/EPA Residential Radon  Survey (Ronca-Battista and others, 1988; Dziuban and
' others, 1990). Forty-two states completed EPA-sponsored indoor radon  surveys between 1986
 and 1992 (fig. 3).  The  State/EPA Residential  Radon Surveys were designed  to be
 comprehensive and statistically significant at the state level, and were subjected to high levels
 of quality assurance and control. The surveys collected screening indoor radon .measurements,
 defined as  2-7 day measurements using charcoal canister radon detectors placed  in the lowest
 livable area of the home.  The target population for the surveys included owner-occupied
 single  family, detached housing units (White and others, 1989),  although attached structures
 such as duplexes,  townhouses, or condominiums were included in some of the surveys if they
 met  the other criteria and had contact with the ground surface.  Participants were selected
 randomly from telephone-directory listings. In total, approximately 60,000 homes were tested
 in the  State/EPA surveys.
     The second source  of indoor radon data comes from residential surveys that have been
 conducted in a specific state or region of the country (e.g. independent  state  surveys or utility
 company surveys).  Several states, including Delaware, Florida, Illinois, New Hampshire, New
 Jersey, New York, Oregon, and Utah, have conducted their  own surveys of indoor  radon.  The
 quality and design of a state or other independent survey are discussed  and referenced where
 the data are used.
                                            II-9     Reprinted from USGS Open-File Report 93-292

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    Data for only those counties with five or more measurements are shown in the indoor
radon maps in the state chapters,  although data for all counties with a nonzero number of
measurements are listed in the indoor radon data tables in each state chapter.  In total, indoor
radon data from more than  100,000 homes nationwide were used in the compilation of these
assessments. Radon data from State or regional indoor radon surveys,  public health
organizations, or other sources are discussed in addition to the primary data sources where
they are available.  Nearly all of the data used in these evaluations represent short-term (2-7
day) screening measurements from the lowest livable space of the homes.   Specific details
concerning  the nature and use of indoor radon .data sets other than the  State/EPA Residential
Radon Survey are discussed in the individual State chapters. .

RADON INDEX AND CONFIDENCE INDEX

    Many of the geologic methods used to evaluate an area for radon potential  require
subjective opinions based on the professional judgment and experience of the individual
geologist.  The evaluations  are nevertheless based on established scientific principles that are
universally  applicable to  any geographic area or geologic setting. This section  describes the
.methods and conceptual  framework used by the U.S. Geological  Survey to evaluate areas  for
radon potential based  on  the five factors discussed in the previous sections.  The scheme is
divided into two basic parts, a Radon Index (RI),  used to rank the general radon potential of
the area, and the Confidence Index (CI), used to express the level of confidence in the
prediction based on the quantity and quality of the data used to make the determination. This
scheme works best if the areas to be evaluated are delineated by geologically-based
boundaries  (geologic provinces) rather than political ones (state/county boundaries) in which
the geology may vary across the area.
    Radon  Index.  Table 1  presents the Radon Index  (RI) matrix. The five factors—indoor
radon data, geology, aerial  radioactivity, soil  parameters, and house foundation  type—were
quantitatively ranked  (using a point value of 1, 2, or 3) for their respective contribution to
radon potential in a given area.  At least some data for the 5 factors are consistently available
for every geologic province.  Because each of these main factors encompass a wide variety of
complex and variable components, the geologists performing the evaluation relied heavily on
their professional judgment and experience in assigning point values to each category and in
determining the overall radon potential ranking.  Background information on these factors is
discussed in more detail  in  the preceding sections of this introduction.
    Indoor  radon was evaluated using unweighted arithmetic means of the indoor radon data
for each geologic area to be assessed.  Other expressions of indoor radon  levels in an area
also could have been  used,  such as weighted averages or annual  averages, but these types of
data'were not consistently available for the entire United States at the time of this writing, or
the schemes were not considered sufficient to provide a means of consistent comparison
across all areas.  For  this report, charcoal-canister  screening measurement data  from the
State/EPA Residential Radon Surveys and other carefully selected sources were used, as
described in the preceding  section.  To maintain consistency, other  indoor radon data sets
 (vendor, state, or other data) were not considered in scoring the  indoor radon factor of the
 Radon  Index if they were not randomly sampled or could not be statistically combined with
 the primary indoor radon data sets.  However, these additional radon data sets  can provide a
 means  to further refine correlations between  geologic factors and radon potential, so they are

                                            II-11     Reprinted from USGS Open-File Report 93-292

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TABLE 1. RADON INDEX MATRIX, "ppm eU" indicates parts per million of equivalent
uraaium, as indicted by NURE aerial radiometric data. See text discussion for details.
                                 INCREASING RADON POTENTIAL
AERIAL RADIOACTIVITY

GEOLOGY*	
 SOIL PERMEABILITY
 ARCHITECTURE TYPE
                                         POINT VALUE
INDOOR RADON (average)
                          negative
                                        1.5 - 2.5 ppm eU
                                            variable
                                                             positive
      1IC FIELD EVIDENCE (GFE) POINTS: GFE points are assigned in addition to points
  for the Sg/' Irtor for specific, relevant geologic field studies. See text for details.

                            HIGH radon        +2 points
                            MODERATE       +1 point
                            LOW             -2 points
                No relevant geologic field studies     0 points
    Geologic evidence supporting:
 SCORING:
                                        Point ranee
                                                   Probable average screening
                                                    indoor r^don for area
             LOW
             MODERATE/VARIABLE
             HIGH
                                      3-8 points
                                      9-11 points
                                     12-17 points
                                                         <2pCi/L
                                                         2 - 4 pCi/L
                                                         >4pCi/L
                      POSSIBLE RANGE OF POINTS = 3 to 17

 TABLE 2.  CONFIDENCE INDEX MATRIX
                                                 CONFIDENCE
                                          POINT VALUE
        FACTOR
                                                            ood coverage/quality
                                        fair coverage/quali
  INDOOR RADON DATA
                                                              no glacial cover
                       questionable/no data
                                                             iroven geol. model
                            questionable
                                                             reliable, abundant
                         questionable/no data
AERIAL RADIOACriVii

GEOLOGIC DATA
SOIL PERMEABILITY
  SCORING:
                 LOW CONFIDENCE
                 MODERATE CONFIDENCE
                 HIGH CONFIDENCE
                                               4-6 points
                                               7-9 points
                                               10 -12 points
                       POSSIBLE RANGE OF POINTS = 4 to 12
                                      n-12    Reprinted from USGS Open-File Report 93-292

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included as supplementary information and are discussed in the individual  State chapters.  If
the average screening indoor radon level for an area was less than 2 pCi/L, the indoor radon
factor was assigned 1 point, if it was between 2 and 4 pCi/L, it was scored 2 points, and if
the average screening indoor radon level for an area 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 (Duval 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 geochemical 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 our 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 Rl 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

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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 points 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 geologi'c 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

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to question the quality or validity of these data.  The other factors were scored on the basis of
the quality and quantity of the data used to complete the RI matrix.
    Indoor radon data were evaluated based on the distribution and number of data points and
on whether the data were collected by random sampling (State/EPA Residential Radon Survey
or other state survey data) or volunteered vendor data (likely to be nonrandom and biased
toward population centers and/or high indoor radon levels).  The categories listed in the CI
matrix for indoor radon data ("sparse or no data", "fair coverage or quality", and  "good
coverage/quality") indicate the sampling density and statistical robustness of an indoor radon
data set.   Data from the State/EPA Residential Radon Survey and statistically  valid state
surveys were typically assigned 3 Confidence Index points unless the data were poorly
distributed or absent in the area evaluated.
    Aerial radioactivity data are available for all but a few areas of the continental United
States and for part  of Alaska.  An evaluation  of the quality of the radioactivity data was based
on whether there appeared to be  a good correlation  between the radioactivity and the actual
amount of uranium or radium available to generate  mobile radon in the rocks  and soils of the
area evaluated.  In  general, the greatest problems with correlations among eU, geology, and
soil-gas or indoor radon  levels were associated with glacial deposits (see the discussion in a
previous section) and typically were assigned a 2-point Confidence Index score.  Correlations
among eU, geology, and radon were generally sound in  unglaciated areas and  were usually
assigned 3 CI points.  Again, however, radioactivity data in some unglaciated  areas may have
been  assigned fewer than 3 points, and in glaciated  areas may be assigned only one point, if
the data were  considered questionable or if coverage was poor.
    To assign Confidence Index scores for  the geologic  data factor, rock types and geologic
settings for which a physical-chemical, process-based  understanding of radon generation  and
mobility exists were regarded as having "proven geologic models" (3  points);  a high
confidence could be held for predictions in such areas.  Rocks for which the processes are
less .well  known or for which data are contradictory were regarded as "variable" (2 points),
and those about which little  is known or for which no apparent correlations have been found
were deemed "questionable"  (1 point).
    The soil permeability factor was also scored based on quality and amount of data. The
three categories for soil permeability in the Confidence  Index are similar in concept, and
scored similarly, to those for the geologic data factor. Soil permeability can be roughly
estimated from grain size and drainage class if data from  standard, accepted soil  percolation
tests  are unavailable; however, the reliability  of the data would be lower than  if percolation
test figures or  other measured permeability data are available, because an estimate of this type
does  not  encompass all the factors that affect soil permeability and thus may be inaccurate in
some instances. Most published soil permeability data are for water; although this is
generally closely related to the air permeability of the soil, there are some  instances when  it
may  provide an incorrect estimate.  Examples of areas in which water permeability data may
not accurately  reflect air permeability include areas with consistently high  levels  of soil
moisture, or clay-rich soils, which would have a low  water permeability but may have a

                                           11-15     Reprinted from USGS Open-File Report 93-292

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significantly higher air permeability when dry due to shrinkage cracks in the soil.  These
additional factors were applied to the soil permeability factor when assigning the RI score, but
may have less certainty in some cases and thus would be assigned a lower CI score.
    The Radon Index and Confidence Index give a general indication of the relative
contributions of the interrelated geologic factors influencing radon generation and transport in
rocks and soils,  and thus, of the potential for elevated indoor radon levels to occur in a
particular area.  However, because these reports are somewhat generalized to cover  relatively
large areas of States, it is highly recommended that more detailed studies be performed in
local  areas of interest,  using the methods and general information in these booklets as a guide.
                                         11-16     Reprinted from USGS Open-File Report 93-292 •

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                                REFERENCES CITED

Akerblom, G., Anderson, P., and 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 the application of geophysics to engineering and environmental problems
       (SAGEEP), Golden, Colorado, March 13-16,1989:  Society of Engineering and Mineral
       Exploration Geophysicists, p.  1-61.

Duval, J.S., Cook, E.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 Otton, J.K., 1990, Soil-gas
       radon compared to aerial and ground gamma-ray measurements at study sites near Greeley
       and Fort Collins, Colorado:  U.S. Geological Survey Open-File Report 90-648,42 p.

Dziuban, J.A., Clifford, M.A.', White, S.B., Bergstein, J.W.,  and Alexander, B.V., 1990,
       Residential radon survey of twenty-three States, in Proceedings of the 1990 International
       Symposium on Radon and Radon Reduction Technology, Vol. HI: Preprints: U.S.
       Environmental Protection Agency report EPA/600/9-90/005c, Paper IV-2,17 p.

Gammage, R.B., Wilson, D.L., Saultz, R.J., and Bauer, B.C., 1993, Subtereanean transport of
       radon and elevated indoor radon in hilly karst terranes:  Atmospheric Environment
       (in press).

Gundersen, L.C.S., Reimer, G.M., and Agard, S.S., 1988a, Correlation between geology, radon
       in soil gas, and indoor radon in the Reading Prong, in Marikos, M.A., and Hansman,
       R.H., eds., Geologic causes of natural radionuclide anomalies: Missouri Department of
       Natural Resources Special Publication 4, p. 91-102.

Gundersen, L.C.S, Reimer, G.M., Wiggs, C.R., and Rice, C.A., 1988b, Map showing radon
       potential of rocks and soils in Montgomery County, Maryland: U.S. Geological Survey
       Miscellaneous Field Studies Map MF-2043, scale  1:62,500.

Gundersen, Linda C.S., 1991, Radon in sheared metamorphic and igneous rocks, in Gundersen,
       Linda C.S., and  Richard B. Wanty, eds., Field studies of radon in rocks, soils, and water:
       U.S. Geol. Survey Bulletin no. 1971, p. 39-50.
                                         U-17     Reprinted from USGS Open-FUe 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/600/9-9l/026b, p. 6-23-6-36.
                                        H-18     Reprinted from USGS Open-File Report 93-292

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Schumann, R.R., Owen, D.E., and Asher-BoHnder, S., 1992, Effects of weather and soil
      characteristics on temporal variations in soil-gas radon concentrations, in Gates, A.E., and
      Gundersen, L.C.S., eds., Geologic controls on radon: Geological Society of America
      Special Paper 271, p. 65-72.

Sextro, R.G., Moed, B.A., Nazaroff, W.W., Revzan, K.L., and Nero, A.V., 1987,
      Investigations of soil as a source of indoor radon, in Hopke, P.K., ed., Radon and its
      decay products: American Chemical Society Symposium Series 331, p. 10-29.

Sterling, R., Meixel, G., Shen, L., Labs, K., and Bligh, T., 1985, Assessment of the energy
      savings potential of building foundations research: Oak Ridge, Term., U.S. Department of
      Energy Report ORNL/SUB/84-0024/1.

Smith, R.C., U, 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, LI., 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 Atlas of the United States of America, sheet
       38077-BE-NA-07M-00, scale 1:7,500,000.

U.S. Department of Energy,  1976, National Uranium Resource Evaluation preliminary report,
       prepared by the U.S.  Energy Research and Development Administration, Grand Junction,
       Colo.: GJO-11(76).

Wanty, Richard B., and Schoen, Robert, 1991, A review of the chemical processes affecting the
       mobility of radionuclides in natural waters, with applications, in Gundersen, Linda C.S.,
       and Richard B. Wanty, eds., Field studies of radon in rocks, soils, and water: U.S.
       Geological Survey Bulletin no. 1971, p. 183-194.

Washington, J.W., and Rose, A.W., 1990, Regional and temporal relations of radon in soil gas to
       soil temperature and moisture: Geophysical Research Letters, v. 17, p. 829-832.

White, S.B., Bergsten, J.W., Alexander, B.V., and Ronca-Battista, M., 1989, Multi-State
       surveys of indoor 222Rn:  Health Physics, v. 57, p. 891-896.
                                          II-19     Reprinted from USGS Open-File Report 93-292

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                                            APPENDIX  A
                                    GEOLOGIC TIME SCALE
Subdivisions (and their symbols)
Eon or
Eonothem
Phsnerozoic2
Prottrozoic
(B)
Archean
(A)
Era or
Enthem
Cenozoic 2
(CD
Mesoroic2
(Md
Paleozoic1
(Pd

Miedi*
Etrty

MiodX
t»"Y
Period, System,
Subperiod. Subsystem
Quaternary2
(Q)
Neopene *
SuDperiod or
T^.-y Su&system IN)
m Paltogene2
11 Su&oeriod or
Subsystem (Pi)
Cretaceous

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                                    APPENDIX  B
                               GLOSSARY OF TERMS
TTn:"s 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  A low, widespread mass of loose rock and soil material, shaped like an open fan
 and deposited by a stream at the point where it flows from a narrow mountain valley out onto a
 plain or broader valley. May also form at the junction with larger streams or when the gradient of
 the stream abruptly decreases.

 alluvium, alluvial General terms referring to unconsolidated detrital material deposited by a
 stream or other body of running water.

 alpha-track detector A passive radon measurement device consisting of a plastic film that is
 sensitive to alpha particles. The film is etched with acid in a laboratory after it is exposed. The
 etching reveals scratches, or "tracks", left by the alpha particles resulting from radon decay, which
 can then be counted to calculate the radon concentration. Useful for long-term (1-12 months)
 radon tests.

 ampnibolite A mafic metamorphic rock consisting mainly of pyroxenes and(or) amphibole and
 plagioclase.
                                           H-21      Reprinted from USGS Open-File Report 93-292

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 argtllite, 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 small
. size and ability to absorb substantial amounts of water, causing them to swell.  The change in size
 that occurs as these clays change between dry and wet is referred to as their "shrink-swell"
 potential.

 concretion A hard, compact mass of mineral matter, normally subspherical but commonly
 irregular in shape; formed by precipitation from a water solution about a nucleus or center, such as
 a leaf, shell, bone, or fossil, within a sedimentary or fractured rock.

 conglomerate A coarse-grained, clastic sedimentary rock composed of rock and mineral
 fragments larger than 2 mm, set in a finer-grained matrix of clastic material.

 cuesta A hill or ridge with a gentle slope on one side and a steep slope on the other. The
 formation of a cuesta is controlled by the different weathering properties and the structural dip of
 the rocks forming the hill or ridge.

 daughter product A nuclide formed by the disintegration of a radioactive precursor or "parent"
 atom.
                                           11-22     Reprinted from USGS Open-File Report 93-292

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delta, deltaic  Referring to a low, 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 Said of igneous rocks that have been  erupted onto the surface of the Earth.
fault A fracture or zone of fractures in rock or sediment along which there has been movement.
fluvial, fluvial deposit  Pertaining to sediment that has been deposited by a river or stream.
foliation A linear feature in a rock defined by both mineralogic and structural characteristics.  It
may be formed during deformation or metamorphism.
formation A mappable body of rock having similar characteristics.
glacial deposit  Any sediment transported and deposited by a glacier or processes associated
with glaciers,  such as glaciofluvial sediments deposited by streams flowing from melting glaciers.
gneiss A rock formed by metamorphism in which bands and lenses of minerals of similar
composition alternate with bands and lenses of different composition, giving the rock a striped or
 "foliated" appearance.
 granite Broadly applied, any coarsely crystalline, quartz- and feldspar-bearing igneous plutonic
rock. Technically, granites have between 10 and 50% quartz, and alkali feldspar comprises at least
 65% of the total feldspar.
 gravel An unconsolidated, natural accumulation of rock fragments consisting predominantly of
 particles greater than 2 mm in size.
 heavy minerals Mineral grains in sediment or  sedimentary rock having higher than average
 specific gravity. May form layers and lenses because of wind or water sorting by weight and size
                                           n-23     Reprinted from USGS Open-FUe Report 93-292

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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 (CaCps).

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.
PhylMte, schist, amphibolite, 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.


                                           n-24     Reprinted ftom USGS Open-File Report 93-292

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physiographic province A region in which all parts are similar in geologic structure and
climateT which has had a uniform geomorphic history, and whose topography or landforms differ
significantly from adjacent regions.

placer deposit See heavy minerals

residual Formed by weathering of a material in place.

residuum  Deposit of residual material.

rhyolite An extrusive igneous rock of volcanic origin, compositionally equivalent to granite.

sandstone A clastic sedimentary rock composed of sand-sized rock and mineral material that is
more or less firmly cemented.  Sand particles range from 1/16 to 2 mm in size.

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.

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 (lithification) of clay or mud.

 shear zone Refers to a roughly linear zone of rock that has been faulted by ductile or non-ductile
 processes in which the rock is  sheared and both sides are displaced relative to one another.

 shrink-swell clay  See clay  mineral.

 siltstone A fine-grained clastic sedimentary rock composeid of silt-sized rock and mineral
 material and more or less firmly cemented. Silt particles range from 1/16 to 1/256 mm in size.

 sinkhole  A roughly circular depression in a karst area measuring meters to tens of meters in
 diameter.  It is funnel shaped and is formed by collapse of the surface material into an underlying
 void created by the dissolution of carbonate rock.

 slope An inclined part of the earth's surface.

 solution cavity A hole, channel or cave-like cavity formed by dissolution of rock.

 stratigraphy The study of rock strata; also refers to the succession of rocks of a particular area.

 surficial  materials Unconsolidated glacial, wind-, or waterborne deposits occurring on the
 earth's  surface.

 tablelands General term for  a broad, elevated region with a nearly level surface of considerable
 extent



                                            n-25     Reprinted fiom USGS Open-File Report 93-292

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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.

vendor data Used in this report to refer to indoor radon data collected and measured by
commercial vendors of radon measurement devices and/or services.

volcanic  Pertaining to the activities, structures, and extrusive rock types of a volcano.

water table The surface forming the boundary between the zone of saturation and the zone of
aeration; the top surface of a body of unconfined groundwater in rock or soil.

weathering The destructive process by which earth and rock materials, on exposure to
atmospheric elements, are changed in color, texture, composition, firmness, or form with little or
no transport of the material.
                                           n-26     Reprinted from USGS Open-File Report 93-292

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                                          APPENDIX C
                                  EPA REGIONAL OFFICES
F.PA  Regional  Offices
                                                                                  EPA  Region
EPA Region 1
JFK Federal Building
Boston, MA 02203
(617)  565-4502 •

EPA Region 2
(2A1R:RAD)
26 Federal Plaza
New York, NY 10278
(212)  264-4110

Region 3  (3AH14)
841 Chestnut Street
Philadelphia, PA 19107
(215)  597-8326

EPA Region 4
345 Courtland Street, N.E.
Atlanta, GA 30365
(404)  347-3907

EPA Region 5 (5AR26)
77 West Jackson Blvd.
Chicago,  IL 60604-3507
(312) 886-6175

EPA Region 6 (6T-AS)
1445 Ross Avenue
Dallas, TX 75202-2733
(214) 655-7224

EPA Region 7
726 Minnesota Avenue
Kansas City, KS 66101
(913) 551-7604

EPA Region 8
 (8HWM-RP)
999 18th Street
One Denver Place, Suite 1300
Denver,  CO 80202-2413
 (303) 293-1713

 EPA Region 9 (A-3)
 75 Hawthorne Street
 San Francisco, CA 94105
 (415) 744-1048

 EPA Region 10
 1200 Sixth Avenue
 Seattle, WA 98101
 (202) 442-7660
Alabama	4
Alaska	10
Arizona	9
Arkansas	6
California	9
Colorado	8
Connecticut	1
Delaware	3
District of  Columbia	3
Florida	4
Georgia	4
Hawaii	9
Idaho	10
Illinois	5
Indiana	5
Iowa	7
Kansas	;	7
Kentucky	-"4
Louisiana	6
Maine	:	1
Maryland	3
Massachusetts	1
Michigan	5
Minnesota	5
Mississippi	4
Missouri	7
Montana	8
Nebraska	7
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	»
Vermont...	1
 Virginia	3
Washington	•	10
 West Virginia	3
 Wisconsin	5
 Wyoming	8
                                                  H-27      Reprinted from USGS Open-File Report 93-292

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                                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       LeeGershner
               Division of Radiation Control
               Department of Health
               4815 Markham Street, Slot 30
               Little Rock, AR 72205-3867
               (501) 661-2301
California      J. David Quinton
               Department of Health Services
               714 P Street, Room 600
               Sacramento, CA 94234-7320
               (916) 324-2208
               1-800-745-7236 in state
Colorado       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 P ^gram
            Connecticut Department of Health
              Services
            150 Washington Street
            Hartford, CT 06106-4474
            (203)566-3122

   Delaware Marai G. Rejai
            Office of Radiation Control
            Division of Public Health
            P.O. Box 637
            Dover, DE 19903
            (302) 736-3028
            1-800-554-4636 In State

    District Robert Davis
of Columbia DC Department of Consumer and
              Regulatory Affairs
            614 H Street NW
            Room 1014
            Washington, DC 20001
            (202) 727-71068

     Florida N. Michael Gilley
            Office of Radiation Control
            Department of Health and
              Rehabilitative Services
            1317 Winewood Boulevard
            Tallahassee, FL 32399-0700
            (904)488-1525
            1-800-543-8279 in state
            Richard Schreiber
            Georgia Department of Human
              Resources
            878 Peachtree SL, 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) 586-4700
                                               IE-28      Reprinted from USGS Open-File Report 93-292

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Idaho
Illinois
Indiana
 Iowa
 Kansas
 Kentucky
Pat McGavam
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
l-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

 Jeana Phelps
 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  BobStilwell
              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 Hendershott
              Division of Radiological Health
              Bureau of Environmental and
                Occupational Health
              3423 North Logan Street
              P.O. Box 30195
              Lansing, MI 48909
              (517) 335-8194

   Minnesota LauraOatmann
              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

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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
                                                n-30      Reprinted from USGS Open-File Report 93-292

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               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 Island    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 MikePochop
             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) 536^250

    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)264^110
                                                n-3i
        Reprinted from USGS Open-File Report 93-292

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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)753^518
               1-800-323-9727 In State

West Virginia   BeanieL.DeBprd
               Industrial Hygiene Division
               West Virginia Department of Health
               151 llth Avenue
               South Charleston, WV 25303
               (304) 558-3526
               1-800-922-1255 In State

Wisconsin      Conrad Weiffenbach
               Radiation Protection Section
               Division of Health
               Department of Health and Social
                  Services
               P.O. Box 309
               Madison, WI53701-0309
               (608)267-4796
                1-800-798-9050 in state

Wyoming      Janet Hough
               Wyoming Department of Health and
                  Social Services
                Hathway Building, 4th Floor
                Cheyenne, WY 82002-0710
                (307) 777-6015
                1-800-458-5847 in state
                                                 11-32      Reprinted from USGS Open-File Report 93-292

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                            STATE  GEOLOGICAL  SURVEYS
                                            May, 1993
Alabama        Ernest A. Mancini
               Geological Survey of Alabama
               P.O. Box 0
               420 Hackbeny Lane
               Tuscaloosa, AL 35486-9780
            '   (205) 349-2852

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) 8824795
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 19716-7501
                (302)831-2833
Hawaii
                                                         Idaho
Florida Walter Schmidt
       Florida Geological Survey
       903 W. Tennessee St.
       Tallahassee, FL 32304-7700
       (904)4884191
William H. McLemore
Georgia Geologic Survey
Rm. 400
19 Martin Luther King Jr. Dr. SW
Atlanta, GA 30334
(404) 656-3214

Manabu Tagomori
Dept. of Land and Natural Resources
Division of Water & Land Mgt
P.O. Box 373
Honolulu, ffl 96809
(808) 548-7539

Earl H. 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  Lee C.Gerhard
        Kansas Geological Survey
        1930 Constant Ave., West Campus
        University of Kansas
        Lawrence, KS 66047
        (913)864-3965
                                               11-33      Reprinted from USGS Open-File Report 93-292

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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) 627^780
Mississippi     S. Cragin Knox
               Mississippi Office of Geology
               P.O. Box 20307
               Jackson, MS 39289-1307
               (601) 961-5500
      Missouri James H. Williams
               Missouri Division of Geology &
                 Land Survey
               111 Fairgrounds Road
               P.O. Box 250
               Rolla, MO 65401
               (314) 368-2100

      Montana Edward T. Ruppel
               Montana Bureau of Mines & Geology
               Montana College of Mineral Science
                 and Technology, Main Hall
               Butte, MT 59701
               (406)496^180

      Nebraska Perry B. Wigley
               Nebraska Conservation & Survey
                 Division
               113 Nebraska Hall
               University of Nebraska
               Lincoln, NE 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 from USGS Open-File Report 93-292

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North Carolina  Charles H. Gardner
               North Carolina Geological.Survey
               P.O. Box 27687
               Raleigh, NC 27611-7687
               (919) 733-3833

North Dakota    John P. Bluemle
               North Dakota Geological Survey
               600 East Blvd.
               Bismarck, ND  58505-0840
               (701)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

               Charles J. Mankin
               Oklahoma Geological Survey
               Room N-131, Energy Center
                100E.Boyd
               Norman, OK 73019-0628
                (405) 325-3031

 Oregon         Donald A. Hull
                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     Ram6n M. Alonso
                Puerto Rico Geological Survey
                  Division
                Box 5887
                Puerta de Tierra Station
                San Juan, P.R. 00906
                (809) 722-2526

  Rhode Island    J. Allan Cain
                 Department of Geology
                 University of Rhode Island
                 315 Green Hall
                 Kingston, RI 02881
                 (401) 792-2265
South Carolina Alan-Jon W. Zupan (Acting)
              South Carolina Geological Survey
              5 Geology Road
              Columbia, SC 29210-9998
              (803) 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
              Nashville, 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
                                                 E-35      Reprinted from USGS Open-File Report 93-292

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  West Virginia Larry D. Woodfork
               West Virginia Geological and
                 Economic Survey
               Mont Chateau Research Center
               P.O. Box 879
               Morgantown, WV 26507-0879
               (304)594-2331

Wisconsin      James Robertson
               Wisconsin Geological & Natural
                 History Survey
               3817 Mineral Point Road
               Madison, WI 53705-5100
               (608)263-7384

Wyoming       Gary B. Glass
               Geological Survey of Wyoming
               University of Wyoming
               Box 3008, University Station
               Laramie, WY 82071-3008
               (307)766-2286
                                              11-36      Reprinted from USGS Open-File Report 93-292

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               EPA REGION 1 GEOLOGIC RADON POTENTIAL SUMMARY
                                            by
              Linda C.S. Gundersen, R. Randall Schumann, and Sandra L. Szarzi
                                  U.S. Geolugical Survey

        EPA Region 1 includes the states of Connecticut, Maine, Massachusetts, New Hampshire,
 Rhode Island, and Vermont For each state, geologic radon potential areas were delineated and
 ranked on the basis of geology, soil, housing construction, indoor radon, and other factors. Areas
 in which the average screening indoor radon level of all homes within the area is estimated to be
 greater than 4 pCi/L were ranked high.  Areas in which the average screening indoor radon level
 of all homes within the area is estimated to be between 2 and 4 pCi/L were ranked
 moderate/variable, and areas in which the average screening indoor radon level of all homes within
 the area is estimated to be less than 2 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 1 is given in the individual
 state chapters. The individual chapters describing the geology and radon potential of the states in
 Region 1, though much more detailed than this summary, still are generalized assessments and
 there is no substitute for having a home tested.  Within any radon potential area homes with indoor
. radon levels both above and below the predicted average likely will be found.
        Figure 1 shows a generalized map of the physiographic/geologic provinces in Region  1.
 The following summary of radon potential in Region 1 is based on these provinces.  Figure 2
 shows average screening indoor radon levels by county, calculated from the State/EPA Residential
 Radon Survey data. Figure 3 shows the geologic radon potential of areas in Region 1, combined
 and summarized from the individual state cnapter.s

 CONNECTICUT

        The Western Uplands of western Connecticut comprise several terranes underlain by
 metamorphosed sedimentary and igneous rocks.  Soils developed on the Proterozoic massifs and
 overlying till in the Proto-North American Terrane (area 23, fig. 1) have moderate to high
 permeability. Equivalent uranium is generally low and indoor radon averaged 2.5 pCi/L over the
 massifs. The carbonate shelf rocks of the Proto-North American Terrane (23, fig. 1) are
 predominantly marble, schist, and quartzite, all overlain in places by glacial till. Indoor radon
  averaged 2.8 pCi/L for homes built on the carbonate shelf rocks. Some homes built on parts  of the
  Stockbridge  Marble have elevated indoor radon levels. The Taconic Allochthons (24,25, fig. 1)
  underlie several fault-bounded area^ in the northern part of the Western Uplands.  The dominant
  rock type is schist of varying composition. Equivalent uranium is generally moderate and
  permeability is low to moderate in this area. Indoor radon in the Taconic Allochthons averaged
  2.7 pCi/L. Overall, these terranes have moderate radon potential.
         Rocks of the Connecticut Valley Synclinorium (26, fig. 1) underlie most of the Western
  Uplands.  These rocks are schist, gneiss, granite, and phyllite, predominantly granitic or
  aluminous in composition. Equivalent uranium is moderate to high with areas of very high
  equivalent uranium over granitic gneisses in the southern portion. The Pinewood Adamellite has
  high radioactivity and generates locally elevated indoor radon levels. Other granites and granitic
  gneisses associated with elevated indoor radon include the Harrison Gneiss, an Ordovician granite
   gneiss, and the Shelton Member of the Trap Falls Formation. These rocks all occur mainly in the
                                             m-1     Reprinted from USGS Open-File Report 93-292-A

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         LAKE
     CHAMPLAIN
            23'
Figure 1. Geologic radon potential areas of EPA Region 1. 1.5-Melange; 2-Seboomook Formation;
3-Metasedimentary rocks, predominantly carbonates; 4-Granite and high-grade metamorphic rocks; 6,7, 8,11-Glacial
lake clay, marine clay; 9,10-Penobscot Formation, granites, and minor metamorphic rocks; 12-Boundary Mountains
Terrane; 13-Gander Terrane; 14-Avalonian Composite Terrane; 15-Northeastern Highlands; 16-Vermont Piedmont;
17-Green Mountains; 18-Champlain Lowland; 19-Vermont Valley; 20,21-Taconic Mountains-Stockbridge Valley;
22-Berkshire Mountains; 23-Proto-North American Terrane;  24,25-Taconic Allochthons; 26-Connecticut Valley
Synclinorium; 27-Western Connecticut Valley Belt; 28,29-Connecticut Valley (Mesozoic Basins); 30-Gneissic domes
of the Eastern Connecticut Valley Belt; 31-Bronson Hill Anticlinorium; 32,33-Merrimack Synclinorium; 34,35, 37  38
40-Avalonian Terrane (includes Hope Valley subterrane); 36-Nashoba and Rhode Island Terranes; 39,44,46-Esmond-
Dedham Terrane; 41-Newbury Basin volcanics; 42-Cape Ann and Peabody plutons; 43-Boston Basin;
45-Narrangansett Basin; 47-Coastal Plain.

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                                                        Bsmt. & 1st Floor Rn
                                                     Average Concentration (pCi/L)

                                                              0.0 to 1.9
                                                              2.0 to 4.0
                                                              4.1 to 6.0
                                                              6.1 to 9.1
                                                          1 u Missing Data
                                                                 100 Miles
Figure 2. Average screening indoor radon levels, by county, for EPA Region 1. Data are from
2-7 day charcoal canister tests. Data from the EPA/State Residential Radon Survey, except for
New Hampshire data, which are from the New Hampshire Division of Public Health Services
radon survey. Histograms in map legend show the number of counties in each category.

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                                                            GEOLOGIC RADON POTENTIAL
                                                                LOW (<2 pCi/L)
                                                            ff.-j MODERATE/VARIABLE (2-4 pCi/L)
                                                                HIGH (>4 pCi/L)
Figure 3. Geologic radon potential areas of EPA Region 1. For more detail, refer to individual
state radon potential chapters.

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southern part of the Connecticut Valley Synelinorium and are associated with the high radioactivity
and with elevated indoor radon. The Nonewaug Granite and the Scranton Member of the Taine
Mountain Formation are also associated with high aeroradioactivity and elevated indoor radon
levels. Graphitic schist and phyllites may be the cause of elevated indoor radon levels associated
with the Wepawaug Schist. Soils are derived from the rocks and overlying tills and have low to
moderate permeability. Indoor radon averages 3.5 pCi/L in the Connecticut Valley Synelinorium.
Because many of the rocks of this terrane have the potential to generate elevated radon levels, this
area is assigned a high geologic radon potential.
       The Central Lowlands of Connecticut (29, fig. 1) are underlain by Triassic and Jurassic
sedimentary and volcanic rocks of the Newark Terrane.  The average indoor radon in the Central
Lowlands was 1.6 pCi/L. Radioactivity in the Hartford and Pomperaug basins is generally low
and the soils have generally low to moderate permeability or are poorly drained. Overall, the
Central Lowlands have a low radon potential.  However, localized uranium occurrences in the
upper New Haven Arkose, the middle Portland Formation, and possibly in the Shuttle Meadow,
East Berlin, and Portland Formations could generate locally elevated indoor radon levels, but they
are not expected to be common or widespread.                   .
        Rocks of the Bronson Hill Anticlinorium, in the Eastern Uplands of Connecticut (31,
fig. 1), include felsic and mafic  schists and gneisses, quartzite, and granite gneiss.  Radioactivity
in the Bronson HOI is moderate to locally high, and equivalent uranium anomalies in the central
part of the area appear to be associated with outcrops of granite gneiss. The soils have low to
moderate permeability with areas of locally high permeability. The Glastonbury granite gneiss and
graphitic schists in the Collins Hill Formation are likely to generate elevated indoor radon levels.
The Monson Gneiss, and schist and granofels of the Middletown Formation, also generate high
average indoor radon levels. Average indoor radon in the Bronson Hill Anticlinorium is
5.6 pCi/L, the highest among the geologic terranes of Connecticut. Overall, this area has  a high
radon potential.
        The Merrimack Synelinorium, in the central part of the Eastern Uplands (33, fig. 1), is
underlain by gneiss, schist, granofels, and quartzite that are intruded by granite gneiss, diorite, and
 gabbro. The area has moderate to high radioactivity. Soils have low to high permeability  but most
 are in the low to moderate range. Indoor radon in the Merrimack Synelinorium averaged 2.7
pCi/L. The Canterbury granite gneiss, which occurs in several broad outcrop bands in the
 northern and central parts of the  area, appears to be associated with elevated radioactivity and with
 moderate to high indoor radon levels.  This area has moderate radon potential overall.
        The Avalonian Terrane,  along the eastern and southeastern borders of Connecticut (34, 35,
 fig. 1), is underlain by granite, granite gneiss, mafic gneiss, and amphibolite.  Granitic rocks
 known to  generate elevated indoor radon levels include the Waterford and Branford Gneisses, and
 the Hope Valley Alaskite Gneiss, which also has a high aeroradioactivity signature, as well as
 locally-occurring graphitic schist and gneiss in the Plainfield Formation. The  overall radioactivity
 signature of the area is moderate to high. Soils of the Avalonian Terrane have low to high
 permeability, with granitic rocks producing sandy, more permeable soils, and mafic and volcanic
 rocks producing silty and sandy soils with slowly permeable, clayey substrata. The indoor radon
 average for this terrane is 3.3 pCi/L. Overall, this area has high radon potential.
                                             m-5    Reprinted from USGS Open-File Report 93-292-A

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MAINE

       The rocks, surficial deposits, and geologic structures of Maine that are most likely to cause
high (>4 pCi/L) indoor radon concentrations include: two-mica granite, alkaline and calc-alkalic
granite, and granodiorite; pegmatites, faults and shear zones; and carbonaceous schist, slate, and
phyllite.  Deposits and rocks likely to cause moderate (2-4 pCi/L) to high (>4 pCi/L) indoor radon
include soils developed on carbonate rocks, especially the interbedded slates and dolostones in
south-central and northeastern Maine; glacial gravels, especially outwash, kames, and eskers;
melange; granitic gneiss; high- to medium-grade metamorphic rocks, and contact metamorphosed
rocks in the vicinity of plutons. Rocks and deposits with moderate to variable radon potential
include felsic metavolcanic rocks, intermediate composition plutonic rocks, and glacial till.  Rocks
likely to cause low indoor radon (< 2 pCi/L) include metamorphosed coarse-grained clastic
sedimentary rocks, mafic metavolcanic rocks, marine clays, and mafic plutonic rocks.
       Most of Maine is underlain by Cambrian-Devonian  stratified metamorphic rocks of igneous
or sedimentary origin that we have ranked from low to high in radon potential. Uranium
concentration generally increases with metamorphic grade and local uranium concentrations may be
present in fractures and faults. Areas in northern Maine underlain by coarse-grained clastic
metasedimentary rocks and tills derived from these rocks generally have low equivalent uranium
and have soils  with low permeability.  Many of the rocks in this area belong to the Seboomook
Formation (area 2, fig.  1). In central and southern Maine, indoor radon is low to moderate  in areas
underlain by coarse-grained clastic metasedimentary rocks. Formations such as the Vasselboro,
which consists of interbedded carbonate rocks and clastic metasedimentary rocks and tends  to be
more calcareous in general, appears to have high indoor radon associated with it in southern
Penobscot County. Central Maine (area 5, fig. 1) is a highly variable area-radon potential varies
from moderate to locally high or low. Locally high areas may be associated with granites, kames,
eskers, carbonate rocks, graphitic or carbonaceous schist, phyllite, and slate. Locally low areas
may be associated with mafic plutonic rocks and clastic metasedimentary rocks. Indoor radon is
highly variable in this area and the type and character of the rocks are variable over short distances.
       Soils and glacial deposits derived from interbedded  carbonate metasedimentary rocks and
slates in the northeastern portion of the State (3, fig. 1) and in the south-central portion of the State
(5, fig. 1) are associated with moderate and high indoor radon. Equivalent uranium is variable
over these deposits but is higher than the dominantly clastic metasedimentary rocks. Soils, tills,
eskers, and kames derived from these rocks generally have  moderate to locally high permeability.
The area underlain by these rock units in the northeastern part of Maine (area 3) has high radon
potential, whereas the rocks in the'south-central part (area 5) are assigned a moderate geologic
radon potential.
       Most of the carbonaceous or graphitic rock units in Maine have moderate to high equivalent
uranium. Some high indoor radon may be associated with  carbonaceous rocks of the Penobscot
Formation in Knox County (area 10, fig. 1). Soils formed  on carbonaceous and graphitic rocks in
Maine have low to moderate permeability.  Areas underlain by these rock units have high geologic
radon potential.
       Plutonic rocks of intermediate to mafic composition generally have low or variable radon
potential. Diorite and mafic intrusives of the New Hampshire series have low equivalent uranium
and comprise two northeast-trending belts along the southern coast and from southern Oxford
County to central Picataquis County.  However, two-mica granites, calc-alkaline granites, and
alkalic plutonic rocks in Maine (in areas 4, 5, 9, fig. 1) have been ranked high in geologic radon
                                           m-6     Reprinted from USGS Open-File Report 93-292-A

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potential.  Uranium concentrations in these types of granites are commonly more than 3 ppm and
are as high as several hundred ppm in Mairie. Two-mica granites are most abundant in the
southwestern part of the State and include the rocks of the Sebago Pluton. Calc-alkaline to alkaline
granites are more abundant in the southern and central part of the State, particularly in the area
northeast of Penobscot Bay and in the Katadhin pluton in central Maine (the part of area 4 in central
Maine). Indoor radon averages are high in the southwestern counties of Maine, which may be due
to the abundance of igneous plutons and high-grade metamorphic rocks in this area. Most of the
areas underlain by igneous plutonic rocks and associated glacial deposits have moderate to locally
high permeability.
       Although there is no obvious anomalous radioactivity associated with major fault and shear
zones in Maine, evidence from other areas of the Appalachians suggests that shear zones can create
isolated occurrences of severe indoor radon, especially when they deform uranium-bearing rocks.
The radon potential of melange, most of which is found in the northwestern part of Maine (area 1
and a small part of area 5, fig. 1), is not well known, but gray to black phyllitic rocks and
deformed zones have the potential to produce at least moderate amounts of radon.  We have
tentatively ranked these rocks as moderate or variable in radon potential.
       The effect of glacial deposits is difficult to assess in Maine because most till is relatively
locally derived and is composed primarily of clasts of the surrounding bedrock.  The areas of
coarse-grained glacial deposits in southwestern Maine and the kame and esker deposits scattered
throughout the State enhance the geologic radon potential due to their very high permeability; these
units have moderate to high radon potential.  The coarser glacial deposits appear to be associated
with the igneous plutonic rocks and belts of calcareous and carbonate metasedimentary rocks.
Along the coast, areas of slowly permeable marine and glaciomarine clay (areas 7,8,11, fig. 1)
probably reduce the radon potential and they are assigned a low geologic radon potential. Glacial
lake sediments with low permeability in Penobscot County (6, fig. 1) appear to be associated with
low indoor radon.  Till with compact, slowly permeable substrata is dominant in much of central
and northern Maine and the rocks underlying these areas are metasedimentary and metavolcanic
rocks that are generally low in uranium.

MASSACHUSETTS

       The metamorphic rocks of the Taconic Mountains and carbonate sedimentary and
metasedimentary rocks of the Vermont-Stockbridge Valley, in westernmost Massachusetts
(area 21, fig. 1), have been ranked moderate in geologic radon potential. Graphitic phyllites and
schist of the Walloomsac Formation have moderate to high radioactivity associated with them and
may produce locally  elevated indoor radon levels. Elevated radon may also be associated with fault
and shear zones, especially in the Taconic Mountains.
        The Berkshire Mountains (area 22, fig. 1) have been ranked moderate overall in radon
potential. Granitic to dioritic gneiss and schist have generally low equivalent uranium associated
with them. Shear zones, pegmatites, and local accumulations of monazite in biotite schist and
gneiss may be sources of locally high indoor radon levels. Soil permeability is low to moderate.
        Metamorphic rocks of the Connecticut Valley Belt, flanking the Mesozoic basins of west-
central Massachusetts (27, 30, fig. 1),  have been ranked moderate in radon potential.
Metasedimentary and metavolcanic gneisses and schists have generally low to moderate
radioactivity associated with them. Soils have generally moderate permeability. The Pauchaug and
Glastonbury granite  gneisses, which form the cores of the Warwick and Glastonbury domes, as
                                            ffl-7    Reprinted from USGS Open-File Report 93-292-A

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well as other locally-occurring granitic rocks in area 30 (fig. 1), may generate locally high indoor
radon levels.  Locally high radon levels are likely to be associated with an area of anomalous
radioactivity at the south end of the Warwick dome and may be associated with faults and shears
throughout the area.
       Mesozoic sedimentary and igneous rocks of the Connecticut Valley (28, fig. 1) have been
ranked moderate or variable in radon potential. Most of the sedimentary rocks have low radon
potential but locally high indoor radon levels may be associated with Jurassic-age black shales and
localized uranium deposits in fluvial sandstone and conglomerates. Geologic radon potential is
low to moderate in glacial lake-bottom sediments, and moderate to high in glaciofluvial deposits
including outwash, lacustrine delta deposits, and alluvium.
       Granitic plutons of the Merrimack Belt, central Massachusetts (32, fig.  1), have been
ranked high in radon potential.  The metasedimentary rocks surrounding the plutons are
predominantly phyllites and carbonaceous slates and schists with moderate to high radon potential.
Mafic metamorphic rocks, which are less common in the Merrimack Belt, have generally low to
moderate radon potential.  Faults and shear zones may produce locally high radon concentrations.
       Granitic plutonic rocks and metamorphic rocks of the Nashoba terrane (36, fig. 1), the
northward extention of the Avalonian terrane (37, fig. 1), and granites of the Cape Ann and
Peabody plutons, in northeastern Massachusetts (42, fig. 1), are ranked high in radon potential.
They are associated with moderate to high radioactivity and the soils developed on these rocks have
moderate to high permeability.  Relationships between radon and underlying bedrock in eastern
Massachusetts, particularly in the Merrimack zone and in these areas, are less distinct, probably
due to the influence of glacial deposits that are made up of a mixture of the rock types underlying
eastern Massachusetts and areas to the north.  The glacial deposits generally have enhanced
permeability and may have enhanced radon emanation due to the redistribution of rock
components, mixing, and grain-size reduction effects of the glacial processes. Volcanic rocks and
soils of the Newbury basin (41,  fig. 1) are ranked moderate in radon potential.
       The Esmond-Dedham terrane, southeastern Massachusetts (44, 46, fig. 1), is ranked
moderate overall in  geologic radon potential.  This area includes a number of granite plutons and
fault zones that may generate high radon levels, as well as mafic metasedimentary and metavolcanic
rocks having low to moderate radon potential. Aeroradioactivity is generally low to moderate with
one anomaly associated with granite of the Rattlesnake Hill Pluton.  Soils in this area have low to
moderate permeability.
       Pennsylvanian sedimentary rocks of the Narragansett basin, southeastern Massachusetts
(45, fig.  1), are associated with low to moderate radioactivity and low to moderate soil
permeability, and have moderate geologic radon potential.  The Norfolk basin is similar to the
Narragansett basin and also has  moderate radon potential. Proterozoic to Pennsylvanian
sedimentary rocks of the Boston basin (43, fig. 1) have been ranked low in radon potential.
Information on soil  characteristics and radioactivity is unavailable for the Boston basin but
radioactivity is assumed to be generally low based on the radioactivity of similar rocks elsewhere in
the State. Soil characteristics are highly variable in urban areas due to human disturbance, and thus
are considered to be variable for this assessment. Black shales and conglomerates in the Boston
basin may have locally high radioactivity and may cause locally elevated indoor radon levels.
       Sediments of the Coastal Plain are found primarily on Nantucket Island and Martha's
Vineyard (47, fig. 1). Areas underlain by Cretaceous and Tertiary sediments have low radon
potential, but areas underlain by the Martha's Vineyard and Nantucket moraines have moderate to
locally high radon potential caused by their relatively higher permeability and better drainage
                                            ffl-8    Reprinted from USGS Open-File Report 93-292-A

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characteristics compared to surrounding areas, and the crystalline rock source component of the
moraines. This is also true of the Buzzard's Bay and Sandwich moraines on Cape Cod. Areas
underlain by highly permeable glacial outwash may also generate locally elevated indoor radon
levels if the soils are not too wet to preclude soil-gas transport.
                   j
NEWHAMPSfflRE

       The Avalonian Composite Terrarie, in southeastern New Hampshire (area 14, fig. 1), is
underlain by the Merrimack Group, Massabesic Gneiss, the Rye Formation and several bodies-of
two-mica granites, alkalic plutonic rocks, and mafic plutonic rocks. Soils in this area have
generally low permeability that is locally moderate to high. The Merrimack Group has low to
moderate equivalent uranium, whereas other rocks have generally moderate to high equivalent
uranium, particularly the Massabesic Gneiss, two-mica granites, and the extensive fault zones.
The Merrimack Group and Rye Formation have overall moderate radon potential, with locally low
radon potential. The Massabesic Gneiss, the granite intrusives, and the fault zones have high
radon potential. Average indoor radon for the townships underlain by Avalonian rocks is
predominantly moderate to high. Overall, the Avalonian Composite Terrane has been ranked
moderate to high in radon potential.
       About half of New Hampshire is underlain by Cambrian-Devonian stratified metamorphic
rocks of igneous or sedimentary origin of the Gander (area 13, fig. 1) and Boundary Mountains
(area 12) Terranes. These rocks have been ranked moderate in radon potential overall.  The
metasedimentary and metavolcanic rocks have variable uranium content, with increasing uranium
as metamorphic grade increases, and contain local uranium concentrations in fractures and faults.
Graphitic slates, phyllites, and schists are may also be possible sources of high indoor radon.
Where indoor radon data are available, the stratified metamorphic rocks appear to be associated
with low to moderate indoor radon in the western portion of the State and with higher indoor radon
in the eastern portion of the State and in the vicinity of plutonic rocks.  Intermediate to mafic
plutonic rocks generally have low or variable radon potential. The Lake Winnipesaukee Quartz
Diorite and the Kinsman Quartz Monzonite appear to have low equivalent uranium and low indoor
radon associated with them, and are ranked low in geologic radon potential.
       Several of the Oliverian domes have distinct radiometric highs associated with them except
for the northernmost and largest of the Oliverian rocks in the northern Gander Terrane, which have
low radioactivity. Indoor radon in the townships underlying this area is variable from low to  high.
The Oliverian rocks and intermediate composition plutonic rocks are ranked moderate or variable in
geologic radon potential.
       Two mica granites, calc-alkaline granites, and alkalic plutonic rocks in New Hampshire
have been ranked high in radon potential. Uranium content of these granites is commonly more
than 3 ppm and ranges to several hundreds of ppm. Two-mica granites occur throughout the
central and eastern portions of New Hampshire.  Calc-alkaline granites occur from east-central to
northwestern New Hampshire.  The largest body of calc-alkaline granite underlies the White
Mountains and has very high radioactivity associated with it Indoor radon levels in several
townships in this area are high.
        High radon concentrations in domestic water are associated with granites, pegmatites, and
faults in some parts of New Hampshire. The radon in these wells may be high enough to
contribute significantly to the radon content of the indoor air.
                                           ffl-9    Reprinted from USGS Open-File Repeat 93-292-A

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 RHODE ISLAND

       The radon potential of Rhode Island appears to be influenced most by the composition of
 the underlying bedrock and secondarily arT^ed by gla ~:o1 deposits. Th greatest percentage of
 homes with 4 pCi/L or more of radon are concentrated in the southern part of the State over the
 Scituate and Narragansett Pier Igneous Suites, and parts of the Esmond Igneous Suite (area 39,
 fig. 1), as well as with two 'areas also noted for high uranium: the northwestern and southwestern
 comers of the State, underlain by the Sterling Plutonic group (38,40, fig. 1), and in the East Bay
 Area, which is underlain by the granites of Southeastern Rhode Island. Igneous intrusive rocks of
 the Scituate Igneous Suite, rocks of the Hope Valley Group, granites of southeastern Rhode
 Island, the Narragansett Pier Granite, and alkalic granites of the Cumberland area have significant
 uranium concentrations and surface radioactivity.  Many of the areas underlain by these rocks also
 have locally derived tills, kames and glacial lake deposits that may contribute significantly to the
 overall high radon potential. The lowest radon potential appears to be associated with the less-
 metamorphosed sediments of the Rhode Island Formation, which is overlain by glacial outwash
 deposits in the northern portion of the Narragansett Lowlands (45, fig.  1).  Low to moderate radon
 appears to be associated with stratified metamorphic rocks of the Blackstone Group, the Harmony
 Group, the Plainfield Formation, parts  of the Esmond Igneous Suite, and scattered stratified
 metamorphic rocks in the Narragansett Lowlands. These areas are ranked moderate or variable in
 geologic radon potential, overall.
       The effect of glacial deposits is complex because most of the materials making up the
 glacial deposits are locally derived and primarily reflect a collection of the surrounding bedrock.
 The majority of soils and glacial deposits are moderate to high in permeability and probably
 enhance the geologic radon potential. In the southern half of the State, stratified glacial deposits
 appear to have lower radioactivity than areas of till over the same bedrock. Stratified glacial
 deposits are most common along valley floors and in the Narragansett Basin, and are thicker and
 generally coarser than the till. The thickness of the stratified deposits may damp the radioactivity
 of the bedrock or indicate an overall lower radioactivity for the glacial deposit Although the
 coarser stratified glacial sediments have higher permeability than some of the tills, their radon
 emanation coefficient tends not to be as high as for some tills.  Tills commonly have higher radon
 emanation because of the higher proportion of finer-grained  sediments.  This is also true of some
 glacial lake deposits.  Thick deposits of outwash sand and gravel blanket much of the northern
 Narragansett Lowlands and appear to have both low radioactivity and low indoor radon associated
 with them; this area is assigned a low geologic radon potential. The southern part of the
 Narragansett Lowlands and East Bay Area, however, have a significantly higher percentage of
 indoor radon readings exceeding 4 pCi/L. This may  be due to the fact that the southern part of the
 Narragansett Lowlands and East Bay Area are dominated by  thin glacial till containing components
 of uraniferous granite and phyllite; this area has a moderate or variable geologic radon potential.
 Another example of the influence of glacial deposits may be seen in the area of the Narragansett
Pier Granite, where high percentages of homes have indoor radon levels greater than 4 pCi/L.
The types of glacial deposits in this area include kames, glacial lake deposits, and till, which are
known to have enhanced radon exhalation. These glacial deposits may also have significant source
components in the adjacent Scituate Igneous Suite and Sterling Plutonic Group as well as the
Narragansett Pier granite, all of which have some elevated uranium concentrations.
                                          m-10    Reprinted from USGS Open-File Report 93-292-A

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VERMONT

       The geologic radon potential of the Champlain Lowlands (area 18, fig. 1) is low, with
°re?s of locally moderate to high radon potential possible. The Vermont Valley (1°. fig. 1) has
generally moderate geologic radon potential. Clay-rich soils with low permeability dominate the
lowlands and include glacial lake and marine clays, which probably reduce the radon potential
significantly. Radioactivity is generally low, with a few scattered high and moderate areas that
appear to be associated with the Clarendon Springs Formation and, possibly, with black shales and
slates in surrounding rock units. Indoor radon levels in the counties underlain by the Champlain
Lowlands are generally less than 4 pCi/L except in Addison County, where out of 26 readings, six
were greater than 4 pCi/L and of these, two were greater than 20 pCi/L.
       The Green Mountains (17, fig. 1) have been rated moderate in radon potential; however,
the radon potential is actually highly variable. Areas with locally high radon potential are those
underlain by metamorphic rocks of Proterozoic age, including quartzite; graphite- and pyrite-
bearing schists and slates; migmatitic schist and gneiss; biotite-rich zones in mica schist; and schist
and gneiss with high concentrations of the minerals monazite, allanite, and zircon; the Cheshire
Quartzite; and local deposits of uranium in vejns and fault zones. Mafic metamorphic rocks such
as amphibolite, hornblende gneiss, gabbro, and serpentinite, have low geologic radon potential.
Radioactivity is variable—low in the southern portion but containing local high radioactivity areas,
moderate to high radioactivity in the central portion, and low in the north.
       The Taconic Mountains (20, fig. 1) have moderate geologic radon potential. Radioactivity
is generally moderate to high, and several rock types appear to have elevated levels of uranium,
especially the carbonaceous sedimentary rocks of the Pawlet Formation. Elevated concentrations
of uranium in the black to gray phyllites and slates are probably the principal radon sources in this
area.
       The Vermont Piedmont (16, fig. 1) has moderate but variable geologic radon potential.
Much of the area is underlain by mafic rocks with low radon potential. Granites, granitic gneiss
and schist, and carbonaceous or graphitic slate and phyllite have the potential to generate moderate
to high indoor radon levels.
       The Northeastern Highlands (15, fig. 1) have moderate radon potential. Plutonic igneous
rocks are abundant in this area and in the northern half of the Vermont Piedmont, but only a few of
the plutons have distinct radiometric anomalies associated with them.  Indoor radon for counties
underlain by these rocks is moderate with the exception of Caledonia County, in which 11 of the
51 indoor radon measurements in the State/EPA Residential Radon Survey were greater than
4 pCi/L.
                                          ffl-11    Reprinted from USGS Open-File Report 93-292-A

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  PRELIMINARY GEOLOGIC RADON POTENTIAL ASSESSMENT OF NEW HAMPSHIRE
                                           by
                      Linda C.S. Gundersen andR. Randall Schumann
                                 U.S. Geological Survey

 INTRODUCTION

   V This chapter presents a discussion of the bedrock and glacial geology, soils, and
 radioactivity of New Hampshire in the context of indoor radon. The New Hampshire Division of
 Public Health Services conducted a survey of 1810 randomly selected homes throughout the state
 to assess the extent of the indoor radon problem in New Hampshire (Pirie and Hannington, 1989;
 and 1990 addendum). Testing began in February 1988 and continued through 1990.  Of the
 homes tested, 27.8 percent had screening indoor radon measurements greater than 4 pCi/L and the
 average indoor radon level was 4.8 pCi/L. Examination of these indoor radon data in the context
 of geology, soil parameters, and radioactivity suggest that the majority 'of townships with high
 (>4 pCi/L) indoor radon levels are underlain by granite and granitic gneiss, particularly in the
 north-central and eastern portions of the State (fig. 1).  Some of these rocks are particularly
 enriched with uranium or have uranium distributed in mineral phases which may be easily
 dissolved by ground water.  High indoor radon may also be associated with pegmatites, major
 fault zones, and high-grade metamorphic rocks. High concentrations of radon in domestic water
 are associated with granite, pegmatite, and faults in some parts of New Hampshire. The radon in
 these wells may be high enough to contribute significantly to the radon content of the indoor air.
      This is a generalized assessment of geologic radon potential of rocks, soils,  and surficial
 deposits of New Hampshire. The scale of this assessment is such that it is inappropriate for use in
 identifying the radon potential of small areas such as neighborhoods, individual building sites, or
 housing tracts. Any localized assessment of radon potential must be supplemented with additional -
 data and information from the locality.  Within any area of a given radon potential ranking, there
 are likely to be areas with higher or lower radon levels than characterized for the area as a whole.
 Indoor radon levels, both high and low, can be quite localized, and there is no substitute for testing
 individual homes. Elevated levels of indoor radon have been found in every state,  and EPA
 recommends that all homes be tested. For more information on radon, the reader is urged to
 consult the local or State radon program or EPA regional office.  More detailed information on state
 or local geology may be obtained from the state geological survey. Addresses and phone numbers
 for these agencies are listed in chapter 1 of this booklet

 PHYSIOGRAPHIC AND GEOGRAPHIC SETTING

      The physiography of New Hampshire is in part a reflection of the erodability of the
 underlying bedrock Ethology (fig. 1) and the effects of extensive glaciation. New Hampshire has
 four major physiographic regions: the Coastal Lowlands, the Eastern New England Upland, the
 Connecticut River Valley, and the White Mountains (fig. 2). Other physiographic regions include
 the Whitefield Lowlands, Winnipesaukee, Ossipee, and Conway Lowlands, Ossipee Mountains,
 Belknap Mountains, and Merrimack Valley. Elevation in the State ranges from sea level in the
 southeastern part of the State to 6,288 feet at ML Washington in the White Mountains.
      The Coastal Lowlands, in the southeastern corner of the State, have relatively flat to gently
rolling topography with elevations generally less than 200 ft above sea level. The area is covered
 by glaciomarine silts and clays that blanket bedrock knolls (Chapman, 1976). The Eastern New


                                         IV-l    Reprinted from USGS Open-File Report 93-292-A

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                  10     20     30 MIH»
Figure 1. Generalized bedrock geologic map of New Hampshire (redrawn from Boudette, 1990)

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 GENERALIZED GEOLOGIC MAP OF NEW HAMPSHIRE
                   EXPLANATION
Jurassic-Cretaceous rocks of the White Mountain and New
England-Quebec igneous succession
Devonian-Carboniferous two-mica granite
Silurian-Devonian intrusive rocks ranging from gabbro to granite in
composition
Late Cambrian-Early Devonian metamorphic rocks


Late Ordovician sheeted gabbro sequence
Middle to Late Ordovician intrusive rocks ranging from gabbro to
syenite in composition
Early Ordovician intrusive rocks ranging from gabbro to granodiorite
in composition
Cambrian-Early Ordovician metamorphic rocks


Late Precambrian metamorphic rocks

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                                 QUEBEC
            MASSACHUSETTS
Figure 2. Physiographic regions of New Hampshire (modified from Chapman, 1976):

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  England Upland covers much of the southern part of the State, and is underlain primarily by
  metasedimentary and metavolcanic rocks.  The eastern part, which is separated from the western
  part by the Merrimack Valley, consists of rolling hills with smooth, glacially-rounded summits
  separated by rounded glacial valleys, somewhat resembling a dissected plateau. Elevations range
  from about 200 to 1500 ft The western part of the Eastern New England Upland is more
  mountainous than the eastern part, averaging between 1500 and 2000 ft in elevation. This area is
  much more dissected than, the eastern part, and the area has distinctly rugged topography.  This
  area includes some higher mountains such as Mt. Monadonock and Mt Kearsarge. The
  Connecticut Valley runs along nearly the entire western border of the State.  It is a wide glacial
  valley carved from metasedimentary and metavolcanic rocks which was occupied by a glacial lake
  during the Pleistocene Epoch. The valley floor and terraces are covered by sandy alluvium and
  glaciolacustrine deposits, with lake-bottom clays underneath.
        The White Mountains occupy most of the northern part of the State.  They are underlain by
  metasedimentary, metavolcanic, and plutonic rocks of Mesozoic and Paleozoic age (Denny, 1982).
  Relief in the White Mountains everywhere exceeds 1000 ft and in places it exceeds 3000 ft.
•  Elevations range from about 2000 ft to more than 6000 ft. Evidence of glacial erosion can be seen
  on even the highest peaks, and alpine glacial features, such as cirques and tarns, are found in the
  central White Mountains, called the Presidential Range (Chapman, 1976). The White Mountains
  are separated from the New England Uplands by the Whitefield Lowlands on the west and by an
  area of "central lowlands", consisting of the Winnipesaukee, Ossipee, and Conway Lowlands, to
  the southeast These lowlands are interrupted by two  small mountain ranges, the Ossipee
  Mountains and the Belknap Mountains, which contain distinct evidence of volcanic activity in the
  form of ring dikes.
        In 1990, the population of New Hampshire was 1,109,252, including 52 percent urban
  population (fig. 3). The population density is approximately 117 per square mile.  The climate is
  highly variable due to its proximity to high mountains  and the Atlantic Ocean. The mean annual
  temperature is 40 °F and the annual precipitation is 40-44 inches (fig. 4).

  GEOLOGIC SETTING

        The geology  of New Hampshire is complex, and the names of rock formations and the way
  rocks are grouped have changed with time. All of the New Hampshire bedrock is  igneous or
  metamorphic and has been divided into lithic/age groups at a level sufficient to pertain to the radon
  problem. Descriptions in this report are derived from the following references: Billings (1955,
  1956); Lyons and others (1982,1986); Hatcher and others (1989); and Boudette (1990). A
  generalized geologic map is given in figure 1. It is suggested, however, that the reader refer to the
  most recent state geologic map (Lyons and others, 1986) as well as other detailed geologic maps
  available from the New Hampshire Department of Environmental Services (1989).  A new
  geologic map of New Hampshire compiled by  the State of New Hampshire and the U.S.
  Geological Survey is in press at the time of this writing. The geology of New Hampshire has been
  divided into three geologic provinces: the Avalonian Composite Terrane, the Gander Terrane, and
  the Boundary Mountains Terrane (fig. 5).  This terminology will be used throughout this report.
                                            IV-5    Reprinted from USGS Open-File Report 93-292-A

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   POPULATION (1990)
      0 to 10000
      10001 to 25000
      25001 to 50000
      50001 to 100000
      100001 to 336073
Figure 3. Population of counties in New Hampshire (1990 U.S. Census data).

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Figure 4.  Average annual precipitation in New Hampshire (modified from Facts on File, 1984,
and National Oceanic and Atmospheric Administration, 1974).

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                            BOUNDARY
                           MOUNTAINS
Figure 5.  Tectonic map of New Hampshire (after Lyons and others, 1982,1986). Dashed lines
indicate boundaries of geologic terranes. Abbreviations for faults:  AF, Ammonoosuc; CBF,
Connary Brook; DPF, Deer Pond; DRF, Deadwater Ridge; FHF, Flint HU1; GF, Grantham; GZF,
Gaza; MNF, Monroe; NF, Newbury; NRF, Nonesuch River, PF, Pinnacle; PPF, Pine Peak; SLF,
Silver Lake; TPF, Thrasher Peaks.

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Avalonian Composite Terrane
       The Avalonian Composite Terrane is underlain predominantly by Late Precambrian
metasedimentary and metavolcanic rocks that are intruded by younger igneous plutons of varying
composition and age. These Precambrian metamorphic rocks are the oldest rocks in the State and
comprise the Merrimack Group and Rye Formation. The Merrimack Group underlies most of the
terrane and consists of micaceous schist, phyllite, slate, and siltstone. In places, the Merrimack
Group is divided into the Kittery, Berwick, and Eliot Formations. The Rye Group, which crops.
out along the coast, consists of micaceous schist of sedimentary origin and amphibolite and biotite
gneiss of volcanic origin. The Late Precambrian Massabesic Gneiss lies just to the northwest of
the Merrimack Group between the Flint Hill Fault and Nonesuch River Fault The Massabesic
Gneiss consists predominantly of felsic metavolcanic rocks with variable amounts of amphibolite,
mica schist, calc-silicate rock, and quartzite.  The gneiss is migmatitic (partially melted) and cut by
younger gneiss of igneous origin. The Massabesic Gneiss was formerly referred to as the
Fitchburg Pluton (Billings, 1956). Two-mica granite of Devonian-Carboniferous age intrudes the
Precambrian metamorphic rocks of the Avalonian Terrane, especially near the Nonesuch River
Fault and in the southern portion  of the terrane. A large diorite body also intrudes the metamorphic
rocks in the eastern part of the terrane.

Gander Terrane
       The Gander Terrane is underlain in part by Qrdovician-Devonian metasedimentary and
metavolcanic rocks and by abundant igneous plutons of variable composition and age that form
north-trending belts or large sheet-like batholiths.  The composition and character of both the
metamorphic and igneous rocks changes from west to east across the terrane, as does the
metamorphic grade of the rocks.  In the west, along the Connecticut River, a broad band of low-
grade metasedimentary and metavolcanic rocks of Ordovician-Devonian age extends the length of
the terrane. On Lyons and others' (1986) map the rock units that comprise this area are the
Ordovician Partridge Formation,  Ammonoosuc Volcanics, and Quimby Formation; the Silurian
Clough Quartzite, Greenville Cove, Rangely, Perry, Small Falls, Madrid, and Fitch Formations;
and the Devonian Littleton and Gile Mountain Formations. Most of these units occur
discontinuously along the Connecticut River Valley on the west side of the Bronson Hill
Anticlinorium. The Littleton Formation and Ammonoosuc Volcanics are the most extensive units
and are found throughout the anticlinorium on the western side. The Ammonoosuc Volcanics are
predominantly mafic and felsic metavolcanic and volcaniclastic metasedimentary rocks, and the
Littleton Formation consists of metapelite, metagraywacke, and metavolcanic rocks. Graphitic and
sulfidic schist and slate make up much of the Partridge and Quimby Formations; however,  the
Quimby also contains metagraywacke. For the most part, the Silurian-age units occur in two
complexly folded and faulted areas in the northern and southern parts of the anticlinorium along the
Connecticut Valley. These include the laminated quartzite and metapelite of the Greenville Cove
Formation; the metamorphosed clastic sediments, metavolcanic rocks, graphitic-sulfidic schists,
calc-silicate rock, iron formation, and metamorphosed volcaniclastic rocks of the Rangely
Formation; quartzite and metapelite of the Perry Mountain Formation; sulfidic-graphitic schist and
calc-silicate rock of the Small Falls Formation; biotite-feldspar granofels, calc-silicate rock, and
sulfidic schist of the of the Madrid Formation; and limestone, calcareous clastic metasedimentary
rocks, and pelitic schist of the Fitch Formation.  The Gile Mountain Formation is exposed in the
Gander Terrane in northwestern Sullivan County and is comprised generally of graywacke,
                                          IV-9    Reprinted from USGS Open-File Report 93-292-A

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phyllite, schist, and slate of variable composition, with amphibolite or greenstone, and felsic
volcaniclastic rocks.
       East of the Bronson Hill Anticlinorium and throughout the rest of the Gander Terrane,
Silurian-Devonian metasedimentary and metavolcanic rocks dominate the metamorphic rocks.
Metamorphic grade increases from west to east The most extensive units include the metapelite,
quartzite, and metaturbidite of the Devonian Littleton Formation; the pelitic schist, metasandstone
and minor calc-siHcate rock of Silurian Rangely Formation; and the quartzites, metapelites, and
metaturbidites of the Silurian Perry Mountain Formations. Sulfidic graphitic schist, calc-silicate
rock, and biotite-feldspar granofels of the Small Falls and Madrid Formations occur to a lesser
extent, especially in the tightly folded areas just west of the Kinsman Quartz Diorite Plutonic Series
(described below).
       Gabbroic to granitic plutons of Ordovician age, referred to as the Oliverian Plutonic Series,
are emplaced as small domes throughout the Bronson Hill Anticlinorium. A very large body of
Oliverian granite and syenite also underlies the northern portion of the terrane at the border between
the Gander and Boundary Mountains Terranes. Many of these domes lie along the axis of the
Bronson Hill Anticlinorium.  On the western side of the anticlinorium is a north-northeast-trending
belt of Devonian-age biotite-muscovite granodiorite, tonalite, and granite called the Bethlehem
Gneiss Intrusive Suite. A parallel belt of granite, granodiorite, tonalite and quartz diorite called the
Kinsman Quartz Monzonite Intrusive Suite lies to the west of the.Bethlehem.  The Spaulding
Quartz Diorite Intrusive Suite is composed of diorite, tonalite, granodiorite, and granite, and lies
south and west of the Kinsman. Jurassic and Cretaceous rocks of the White Mountain and New
England-Quebec Plutonic Suites form several bodies in the eastern half of the Gander Terrane.
The most prominent of these are the calc-alkaline Jurassic Conway Granite and related Jurassic
Osceola Granite, granites, syenite, diorite, and moat volcanics that comprise the White Mountains.
Cretaceous biotite granite and volcanic rocks also underlie the area of Ossipee and the south end of
Lake Winnipesaukee.  Quartz-diorite, tonalite, granodiorite, and granite of the Winnipesaukee
Quartz Diorite underlie most of the area around the lake.  Bodies of Devonian-Carboniferous two-
mica granite occur throughout the Gander Terrane west of the Bethlehem Gneiss Intrusive Suite
and in parts of the Avalonian and Boundary Mountains Terranes.
       The Ordovician-Devonian igneous rocks of the northern Gander Terrane are continuous
into the Boundary Mountains Terrane. The Gander Terrane is separated from the Boundary
Mountain Terrane by an indistinct boundary, marked in part by the Ammonoosuc Fault.

Boundary Mountains Terrane
       The Boundary Mountains Terrane of New Hampshire comprises folded and faulted, north-
trending belts of Cambrian-Devonian metasedimentary and metavolcanic rocks in the northern half
of the terrane, which are complexly deformed and intruded by igneous plutons in the southern half
of the terrane. The Gile Mountain, Frontenac, Perry Mountain, Littleton, and Dead River
Formations are the major belts of rock from west to east.  The Rangely, Dixville, Ammonoosuc,
Fitch, Clough, and Waits River Formations underlie smaller areas in  the southern half of the
terrane.  The Waits River Formation crops out in the southern portion of the belt of Gile Mountain
Formation. The Waits River consists of calcareous schist and granofels, with interbedded
metapelite and metagraywacke and minor mafic metavolcanic rocks.  The eastern portion of the
Gile Mountain Formation is composed of the Meetinghouse Slate Member, consisting of gray
slate, phyllite, and graywacke and bounded on the east by the Monroe Fault. The Silurian-
Ordovician Frontenac Formation lies east of the Monroe fault and comprises feldspathic sandstone,
                                          IV-10    Reprinted from USGS Open-File Report 93-292-A

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gray slate, phyllite, and quartz-mica schist with layers of greenstone, green slate, and felsic
metavolcanic rocks. The main body of greenstone in the Frontenac is fault-bounded by the
Deadwater Ridge fault to the west and the Connary Brook fault to the east Felsic and minor mafic
metavolcanic rocks of the Perry Formation and chlorite schist, amphibolite, and minor felsic
metavolcanic rocks and sulfidic phyllites of the Rangeley Formation lie to the east of the Connary
Brook fault These rocks are bounded to the east by the Deer Pond fault and the Devonian Littleton
Formation. The Thrasher Peaks fault bounds the northeastern edge of the Littleton and separates it
from the Dead River Formation to the east Part of the southern portion of the belt of Littleton
Formation is bounded on the east by the Ordovician, rusty-weathering  sulfidic to graphitic schist
and quartzite of the Dixville Formation.  The Cambrian-early Qrd.ovician Dead River Formation
consists of thinly laminated metapelite and quartzite described as "pin-striped." The belts of rock
just described extend southward to just below the Mohawk River in the southern portion of the
terrane. South of the main body of Dead River Formation is an area underlain by the
Ammonoosuc Volcanics. The Dead River, Rangely, Gile Mountain, Dixville, and Waits River
Formations also underlie small areas in the central and southern portions of this terrane. The
southwestern extension of the terrane in northern Grafton County is underlain by the Rangely and
Littleton Formations, the Ammonoosuc Volcanics, the Clough Quartzite, and the Fitch Formation.
Devonian two-mica granite, Jurassic alkalic and calc-alkalic granites, and Ordovician gabbro to
diorite intrude the metasedimentary  and metavolcanic rocks in the southern and eastern portions of
the terrane.           .                               ,

GLACIAL GEOLOGY

       Stratigraphic evidence from New England and the Gulf of Maine indicates that there were at
least four, and as many as six, glacial advances in this region during the Pleistocene epoch.  Two
Wisconsinan (Late Pleistocene) till units have  been identified in New Hampshire from surface and
subsurface data (Stone and Borns, 1986). The "lower till" is probably  early Wisconsinan in age, it
is typically relatively fine grained (silt loam to silty clay loam) and compact, and it has a weathered
zone or paleosol at the top (Stone and Borns, 1986).  jn some areas, the "lower till" may consist of
more than one till unit, representing deposits of more than one glacial advance. In Northern New
Hampshire, the Nash Stream Till (Koteff and Pessl, 1985) correlates with the "lower till" in most
of New England (Stone and Borns,  1986). The "upper till" is late middle Wisconsinan to late
Wisconsinan and it is a single surface till with  a dominantly silty to sandy matrix. Variations in
dominant grain size, color, and stoniness of the tills are closely related to bedrock lithology (Stone
and Borns,  1986). Glaciers moved in a generally north-south or northwest-southeast direction
across New Hampshire, terminating on Long Island, New York; Martha's Vineyard,
Massachusetts; and George's Bank,  off Cape Cod, at their maximum extent (Stone and Borns,
1986). Glacial lakes occupied several valleys during  the interstades and following the final retreat
of glaciers from New Hampshire, which occurred about 12,500 years ago (Stone and Borns,
1986). Glacial Lake Hitchcock occupied the Connecticut Valley from about 16,000 to 13,500
years ago, and marine sand, silt, and clay was  deposited in the coastal zone of southeastern New   .
Hampshire when sea level rose due to melting  of glacial ice. The sea occupied the area from about
13,800 years BP to about 11,500 years BP, when post-glacial rebound caused the land surface to
re-emerge above sea level (Stone and Borns, 1986).
       Till is the most common and widespread type of glacial deposit in New Hampshire
(fig. 6). It is an unsorted deposit of gravel, sand, silt, and clay, with some cobbles and boulders.
                                          IV-I1    Reprinted from USGS Open-File Report 93-292-A

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                   EXPLANATION

            I TILL—unstratified mix of gravel, sand, silt, and
            I clay

             ICE-CONTACT STRATIFIED DRIFT—mainly
             sand and gravel deposits of kames, kame terraces,
             andeskeis

            j OUTWASH AND ALLUVIUM—mainly sand
            i and gravel deposited by glacial meltwater streams
             and modem rivers

            ! GLACIOLACUSTRINE SEDIMENTS—
            ! stratified silt and clay deposited by glacial lakes;
             may be varved
      t:'-:f| MARINE SEDIMENTS—stratified silt and clay
      r'i  •'•' deposited by postglacial marine inclusions •
                10      20 Mllas
Figure 6.- Generalized glacial map of New Hampshire (modified from Flint and others, .1959).

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 Thickness of the till ranges from a thin, discontinuous veneer of less than one meter to locally more
 than 100 m, but it is generally in the range of 4-6 m thick (Goldthwait and others, 1951). There
 are two distinctly different types of till in New Hampshire. One is a dense, compact till containing
 rounded, striated boulders and a relatively high amount of erratics (cobbles and boulders from
 distant bedrock sources), called basal till.  Although its compactness suggests a relatively high clay
 content, the clay content of basal till is generally less than 30 percent; however, basal till contains
 more clay than ablation till and it usually contains a significant amount of silt, which together with
 the"clay is responsible for the compactness of the basal till. The other type of till is a loosely
 packed, very sandy till containing angular boulders of local bedrock and little or no clay. This type
 of till is called ablation till. Ablation till overlies either basal till or bedrock. These two types of till
 are found throughout most of New England and are more commonly referred to simply as the
 "upper till" and "lower till" (Goldthwait and others, 1951; Stone and Borns, 1986; Richmond and
 Fullerton, 1987, 1991,1992). The two types of till are not differentiated on the surficial geologic
 map of New Hampshire (Goldthwait and others, 1950), of which figure 6 is a generalized version.
 Glacial landf orms typically associated with till include drumlins, kettles, and moraines. Moraines,
 accumulations of till deposited at the margins of retreating ice, are not common features in New
 Hampshire, due in large part to the State's rugged topography.  Drumlins, however, are very
 common in the southern part of the State (Goldthwait and others,  1951).
        Glaciofluvial deposits are stratified sediments deposited by glacial meltwater adjacent to or
 in front of the ice margin. These ice-marginal or ice-contact deposits include kames, kame
 terraces, kame moraines, eskers, and outwash deposits. Except for outwash, all of these features
 exhibit sedimentary structures indicative of slumping that occurred when the ice against which they
 were deposited melted away. Characteristic of all types of glaciofluvial deposits is their coarse
 texture, being composed primarily of sand and gravel. Kame terraces formed between the edge of
 a glacier and a valley wall. Kame moraines are deposits of gravel  that formed in front of the glacier
 and they have topography similar to that of a till moraine. Like moraines composed of finer-
 grained till, kame moraines mark the position of a former glacial border. Eskers are sinuous ridges
 composed of outwash sand and gravel deposited by rivers that flowed in tunnels underneath an ice
 sheet or valley glacier.  Eskers in New Hampshire range from highly discontinuous to long,
 sinuous ridges that can be traced for many kilometers, such as the  esker chain that stretches 23 km
.from Lyme to  West Lebanon (Goldthwait and others, 1951).  Kames, terraces, and eskers
 constitute a significant source of sand and gravel. Outwash sand and gravel was deposited in some
 valleys by rivers that drained the melting glaciers. In  New Hampshire the outwash commonly
 covers the floors of valleys in a broad, flat sheet called an outwash plain. One such outwash plain
 north of Dover measures 14 km long by 3 km wide. Outwash deposits east of Concord are more
 than 20 m thick (Goldthwait and others, 1951). Sand plains are most common in southeastern
 New Hampshire, where they occur with kames and kame terraces  in parallel, northwest-trending
 belts several km apart (Goldthwait and others, 1951).
       Lacustrine (lake) and marine sediments are layered silts and clays deposited by large
 postglacial lakes and in marine (ocean) environments, respectively. Because the valleys and
 lowlands were the sites of final melting of stagnant ice masses, drainage was blocked and many
 small lakes developed. Glacial lakes occupied the Connecticut, Merrimack, and Ashuelot valleys
 (Goldthwait and others, 1951).  Lake bottom sediments are composed of silt and clay; shallow-
 water sediments are composed primarily of sand, and beach and delta deposits contain primarily
 sand and gravel. Marine sediments have characteristics similar to lacustrine sediments, in that they
 also are classified into fine-grained bottom deposits, sandy shallow-water deposits, and sand and
                                          IV-13    Reprinted from USGS Open-File Report 93-292-A

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gravel beach and deltaic deposits. Marine sediments were deposited in the coastal lowland of
southeastern New Hampshire when sea level rose due to glacial melting. Marine sediments are
distinguished from lake deposits by the presence of fossil shells and by the absence of varves
(alternating layers of finer and coarser sediment or lighter and darker-colored sediment related to
storms or seasonal deposition in lakes).

SOILS

       Soils in New Hampshire include Inceptisols, mineral soils with weakly expressed horizons
of alteration or accumulation of metal oxides such as iron, aluminum, or manganese; Spodosols,
mineral soils with subsurface accumulations of organic matter and compounds of aluminum and
iron that have been leached from the surface and transported downward through the soil; Entisols,
mineral soils with no discernible horizons because their parent material is inert (such as quartz
sand) or because the soils are very young; and Histosols, wet, organic-rich soils (peat and muck)
in swamp and marsh environments (U.S. Soil Conservation Service, 1987). Figure 7 is a
generalized soil map of New Hampshire. The following discussion is condensed from Pilgrim and
Peterson (1979). This report and other State- and county-scale soil survey reports should be
consulted for more detailed descriptions and information.

Soils in Valleys and Lowlands
       Soils of the valleys (fig. 7) are characterized by nearly level floodplains of river valleys in
New Hampshire.  The soils are deep, well drained to excessively drained, silty, sandy, and
gravelly soils formed on floodplains and alluvial terraces. These soils are moderately to highly
permeable and the water table is more than three feet, and usually more than five feet, below the
ground surface. Soils on coastal lowlands are restricted to the southeastern part of the State
(fig. 7). The soils are deep, poorly drained to excessively drained, clays and clayey and silty
loams. About 10 percent of this map unit is formed on sand and gravel. The soils have low to
moderate permeability except where they are formed on gravelly terraces or delta deposits, which
have high permeability. Many of the soils in this map unit are wet for extended periods.  Areas
underlain by tidal marsh soils include Seabrook, Hampton, North Hampton, and part of Rye
(Pilgrim and Peterson,  1979), along the coastline in southeastern New Hampshire (fig. 7). The
map area also includes some beaches and sand dunes. Tidal marsh soils are mostly deep and very
poorly drained. They are  subject to inundation by tidal waters twice daily. The surface two or
three feet of these soils is  organic matter (peat and muck), typically underlain by sand, silt, or clay.
In some areas, the organic materials overlie bedrock. These soils have moderate to high
permeability to water but their gas permeability is low due to constant wet conditions.

Soils on Hills and Uplands
       Soils on hills and low mountains in southeastern and south-central New Hampshire are
deep, moderately well drained to excessively drained, clayey, silty, and sandy loams with compact
substrata.  Gas and water movement through the soil is restricted by the hardpan layer, giving
these soils generally low to locally moderate permeability. Soils on hills and low mountains in
central and southwestern New Hampshire are deep, moderately well to well drained, loams, sandy
loams, and gravelly loams with a distinct hardpan layer about two feet below the ground surface.
Air and water movement through the soil is restricted by the hardpan layer, giving these soils low
                                          IV-14    Reprinted from USGS Open-File Report 93-292-A

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                                                                  45°
                                                                      44°
Figure 7. Generalized soil map of New Hampshire (after Pilgrim and Peterson, 1979).

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           GENERALIZED SOIL MAP OF NEW HAMPSHIRE
                               LEGEND
      SOILS OF VALLEYS (Spodosols, Entisols, and Inceptisols)—deep, well and
      excessively drained, silty, sandy, and gravelly soils; moderate to high permeability


      SOILS ON COASTAL LOWLANDS (Inceptisols)—deep, poorly to excessively
      drained, clays, clay loams, and silty loams; low to moderate permeability, about
      10% of map unit is gravelly soils of terraces with high permeability


      SOILS ON HILLS AND LOW MOUNTAINS IN SOUTHEASTERN AND SOUTH-
      CENTRAL NEW HAMPSHIRE (Inceptisols)— deep, moderately to excessively
      drained, clayey, silty, and sandy loams with compact substrata; low permeability
      SOILS ON HILLS AND LOW MOUNTAINS IN CENTRAL AND SOUTHWESTERN
      NEW HAMPSHIRE (Spodosols)—deep, moderately well to well drained, loams,
      sandy loams, and gravelly loams with a subsurface hardpan layer; low to locally
      moderate permeability

pTvl SOILS ON HILLY UPLANDS BORDERING THE CONNECTICUT RIVER VALLEY
'"•I (Inceptisols)— shallow to deep, well drained, loams, silt loams, and silts formed on tills;
      low to moderate permeability
      SOILS ON HILLS AND LOW MOUNTAINS IN NORTHERN NEW HAMPSHIRE
      (Spodosols)— shallow to deep, moderately well to well drained, silty and sandy
      loams with a hardpan substrata; low permeability, locally moderate to high
      permeability where soils are sandy
     SOILS OF THE WHITE MOUNTAINS AND ASSOCIATED FOOTHILLS
   iJ (Spodosols)—shallow to deep, well drained, loams; mostly moderate permeability,
     soils with compact substrata have low permeability
     SOILS DEVELOPED ON CONWAY GRANITE {Spodosols)— shallow to deep,
     well drained, sandy and gravelly loams; high permeability
     SOILS ON ALPINE AND SUBALPINE AREAS OF THE WHITE MOUNTAINS
     (Spodosols)— moderately deep to deep, silty and sandy soils; moderate to
     locally high permeability
     SOILS OF TIDAL MARSHES (Histosols)—deep, poorly drained, organic
     soils; moderate to high permeability, typically wet

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 to locally moderate permeability. Some soils of this map unit have perched water tables of short
 duration during the wet season.  Soils on hilly uplands bordering the Connecticut River Valley
 occur from Chesterfield in Cheshire County north to Piermont in Grafton County (fig. 7). These
 soils are shallow to deep, well drained, loams, silt loams, and silts formed on compact nil and silty
 till. Soils formed on compact till have low permeability and those formed on silty till have
 moderate permeability.  Soils on hills and low mountains in northern New Hampshire are shallow
 to deep, moderately well drained to somewhat excessively drained, silty and sandy loams. Soils of
 this map unit formed on compact tills have low permeability due to the hardpan layer about two feet
 below the ground surface. The fabric of the hardpan typically consists of alternating layers of
 compact sand and loam. Soils with hardpans commonly have perched water tables for short
 duration during the wet season.  Soils of this map unit formed on sandy tills have moderate to high
 permeability.
        Soils of the White Mountains and associated foothills are shallow to deep, well drained,
 loamy soils. About 20 percent of the soils in this map unit have a compact substratum and,
 consequently, low permeability.  The remainder of the soils in this map unit have moderate
 permeability. Soils formed on the Conway Granite in and around the town of Conway are shallow
 to deep, well drained, sandy and gravelly loams with high permeability.  Soils on alpine and
 subalpine areas of the White Mountains occupy areas with elevations greater than 2500 feet.  These
 soils are moderately deep to deep, silty and sandy soils formed in bedrock and glacial till. They
 have well-developed organic surface horizons and subsurface accumulations of aluminum, iron,
 and organic matter. Although not discussed by Pilgrim and Peterson (1979), these soils probably
 have moderate to locally high permeability.

 RADIOACTIVITY

       An aeroradiometric map of New Hampshire (fig. 8) compiled from the National Uranium
 Resource Evaluation (NURE) flightiine data (Duval and others, 1989) shows several areas of high
 equivalent uranium (eU) in the State, most of which are associated with uranium-bearing igneous
 plutons. Low eU (

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Figure 8. Aerial radiometric map of New Hampshire (after Duval and others, 1989). Contour
   lines at 1.5 and 2.5 ppm equivalent uranium (eU). Pixels shaded at 0.5 ppm eU increments;
   darker pixels have lower eU values; white indicates no data.

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of 3.4 ppm for the Bethlehem Gneiss. He also noted that much of the uranium in these rocks was
concentrated on grain boundaries and in initerstitial spaces, not necessarily within accessory
minerals. Wathen (1987) also found that uranium in two-mica granite was found as grain
coatings.
       As part of the NURE program, Chiasma Consultants, Inc. (1982) analyzed a number of
rock types in New Hampshire. The alkalic, biotite-rich Conway Granite had the highest
concentrations of uranium, with typical concentrations of 4-31 ppm UaOg- They also indicated
that concentrations average between 20-40 ppm UaOg in red granite and aplitic dikes. Jaupart and
others (1982) report average uranium concentrations of 12.6-15.9 ppm in the White Mountain
granites, based upon more than 1000 gamma-ray spectrometer measurements in New Hampshire.
The more amphibole-rich Mount Osceola Granite of this series has consistently lower values of
UsOg (less than 19  ppm UsOg reported by Chiasma Consultants, Lie, 1982) and Bothner (1978)
reports lower surface radiation values (1.6 times background versus 2-5 times background for the
Conway Granite). The two-mica granites of the New Hampshire series have eU of 2.5 to greater
than 5.5 ppm on the aeroradiometric map (fig. 8). These also have elevated uranium
concentrations—for example, Chiasma Consultants, Inc. (1982) reported a range of 10-800 ppm
UsOg, Bothner (1978) reported an average of 15 ppm U, and Jaupart and others (1982) reported
an average of 7.6 ppm, based on 145 gamma-ray spectrometer measurements.  Two-mica granites
that have exceptionally high uranium concentrations occur northeast of Lake Winnipesaukee, on
the eastern margin of the White Mountains, and north of Sunapee Lake. Additional occurrences of
high uranium concentrations in two-mica granites include the areas around Concord and Rochester,
north of Newfound Lake, north of the White Mountains, southeastern Cheshire County, and
central Coos County. The Bethlehem Gneiss Intrusive Suite (granitic gneiss) in western New
Hampshire defines  a northeast-trending radiometric high with eU of 2.5 to less than 4.5 ppm
(fig. 8). Lyons (1964) indicates an average uranium concentration of 3.4 ppm based on 28
measurements. The Kinsman tonalite and quartz monzonite, which forms a parallel belt east of the
Bethlehem gneiss, defines an area of moderate eU values (2-2.5 ppm) on the aeroradiometric map,
except where it is adjacent to White Mountain series intrusives which have values of 3.0-4.5 ppm.
The Winnipesaukee quartz diorite in the vicinity of Lake Winnipesaukee and in southeastern
Cheshire County has distinctly low radioactivity on the aeroradiometric map (1.0-2.5 ppm), and
Jaupart and others (1982) report U concentrations of 0.5-1.9 ppm. Diorite and granodiorite of the
Exeter pluton west of Portsmouth have moderate to high radioactivity on the aeroradiometric map
(2.0 to greater than 3.5 ppm) and have an average uranium concentration of 2.8 ppm (Roy and
others,  1968).
       The Precambrian Massabesic gneiss is a migmatitic biotite gneiss or quartz monzonite that
forms a northeast-trending belt in southeastern New Hampshire with eU  values of 2.5 to 4.5 ppm
on the aeroradiometric map. Jaupart and others (1982) reported uranium concentrations in the
Massabesic of 0.7-6.7 ppm.  Ordovician granite and quartz monzonite of the Oliverian plutonic
series produce moderate to high aeroradiometric patterns (less than 2.5 to greater than 3 ppm eU)
along the western border of New Hampshire and in a northeast-trending belt, mostly in southern
Coos County.  Bendix Field Engineering (1982) reports UsOg values of 5-10 ppm and Jaupart and
others (1982) provide one analysis of 1.9 ppm U.
       Most of the metasedimentary and metavolcanic rocks exhibit low  to moderate eU (0-2.5
ppm) on the aeroradiometric map and some units have moderate to high eU where they are in
contact with the Conway granite or New Hampshire Series two-mica granites.  The higher
concentrations are in part due to pegmatite dikes  of granite incorporated into the surrounding rocks
                                          IV-19    Reprinted from USGS Open-File Report 93-292-A

-------
 and in part due to higher metamorphic grades of the surrounding rocks. The Ordovician-Devonian
 stratified metamorphic rocks have elJ values greater than 2 ppm adjacent to the White Mountain
 batholith.  Other areas of the metamorphic rocks are mostly between 1 and 2 ppm eU. The highest
 values are associated with the sillimanite-grade metamorphism. A similar relationship is indicated
 by Jaupart and others (1982), who reported uranium concentrations in the range of 0.8 to 16.9
 ppm, with the highest values associated with rocks in proximity to uranium-rich granites. Jaupart
 and others (1982) indicate U concentrations of 1.0-3.1 ppm for schist in the Bronson Hill
 Anticlinormm, 1.8-3.6 ppm for the Berwick, and a single measurement of 2.6 ppm for the Rye.
 The Ordovician Ammonoosuc Volcanics also have consistently moderate to high eU on the
 aeroradioactivity map Gess than 2 to less than 3). Jaupart and others (1982) report a single
 measurement of 4.4 ppm U in a sample adjacent to an Oliverian granite.
       It is difficult to associate specific geologic units with uniformly low eU values (0-1.5
 ppm). In the Merrimack Group, the amphibolite-rich metavolcanics of the Rye Formation and the
 Kittery Quartzite both appear to have low eU. Along the western edge of the State, Ordovician
 chloritic schistose quartzite is associated with low equivalent uranium. Jaupart and others (1982)
 report a single measurement of 0.4 ppm U from Ordovician schistose quartzite.  The Ordovician
 Gile Mountain and Waits River Formations in the northern part of the State have low eU, although
 Jaupert and others (1982) report a single uranium measurement of 1.9 ppm in the Gile Mountain
 from that area.  Cambro-Ordovician gabbros and serpentinites with low radioactivity underlie small
 areas around White Mountain intrusives in the central part of the State.

 INDOOR RADON

       The New Hampshire Division of Public Health Services initiated a survey of randomly-
 selected homes throughout the State to  assess the extent of the indoor radon problem in New
 Hampshire. Testing began in February 1988 and continued through 1990.  The majority of
 townships with high indoor radon are underlain by uranium-bearing granites, particularly in the
 northern and western portions of the State.
       Indoor radon data from 1810 homes sampled in the Department of Public Health
 Services/Governor's Energy Office survey conducted in New Hampshire during the winter heating
 seasons from 1988-1990 are shown by  township in figure  9 and in Table 1. A map of counties is
 included for reference (fig. 10). The data represent short-term (2-7 day) charcoal canister tests.
 The maximum value recorded in the survey was 478.9 pCi/L. Townships with indoor radon
 averages exceeding 4 pCi/L are clustered in central and eastern Hillsborough County; most of
 Rockingham and Strafford Counties, particularly in the upland parts of these counties, and in the
 southern Coastal Lowland; eastern Carroll County; southern Coos County;.western and central
 Grafton County; and locally in other areas of the State.
       Radon contributed from domestic well water may also constitute a significant indoor air
 radon problem in New Hampshire. Several studies indicate that degassing of radon from water
 can cause spikes in indoor air concentrations, especially during peak water-use periods (Hess and
 others, 1986; Nazaroff and Nero,  1988). Several studies of radon in ground water and geology
 for New Hampshire were compiled by Paulsen (1991) and are shown in Table 2. These studies
found that the distribution of radon in ground water is primarily controlled by bedrock geology.
The distribution of uranium within the rock is also an important control (Wathen, 1987). On the
average, the felsic igneous plutonic rocks are sources of the highest radon in ground waters. Two-
mica granites are especially good radon  sources, because the uranium in them is in relatively high
                                         IV-20   Reprinted from USGS Open-File Report 93-292-A

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       Average indoor radon
              (pCi/L)

             0-1.9
s!£!~ ^C'A ^Vf raSei?
-------
Table 1. New Hampshire 1987-1990 Winter Indoor Radon Survey data by Town. Data are from
short-term charcoal canister measurements.
Town
Acworth
Albany
Alexandria
Allenstown
Alstead
Alton
Amherst
Andover
Antrim
Ashland
Atkinson
Auburn
Bamstead
Barrington
Bartlett
Bath
Bedford
Bennington
Benton
Berlin
Bethlehem
Boscawen
Bow
Bradford
Brentwood
Bridgewater
Bristol
Brookfield
Brookline
Campion
Canaan
Candia
Canterbury
Carroll
Center Harbor
Charlestown
Chatham
Chester
Chesterfield
Chichester .
Claremont
Clarksville
Colebrodft
Columbia
Concord
No. of Meas.
6
2
4
8
5
5
16
7
7
7
15
14
3
11
3
7
19
6
5
26
6
2
17
2
6
4
6
4
6
5
8
13
6
5
2
7
2
10
6
2
8
2
8
4
21
Mean v " Town
2.2 x\~ Conway
7.7 ^Cornish
1.6 "'i__ Croydon
6.7 , -* Dafton
1.8 ~v;Danbury
2.2 %fc*i. Danville
8.6 - - Deerfield
4.5 *-r>*Deering
0.7 ^ - \Deny
3.4 , Dixville
8.6 ',;?: " Dorchester
3.9 ;-\ ^- Dover
4.7 , -A Dublin
3.1 i;f Dummer
7.7 ' s-s Dunbarton
2.5 Durham
7.6- ;; East Kingston
0.8 "^SrlEaston
3.0 <•""*" -.Eaton
5.4 .rT^Effingham
3.8 -^.Ellsworth
0.8 ,H, .Enfield
3.6 - Epping
7.7 ^'lEpsom
3.1 '" Errol
2.8 ^4"«. Franklin
4.9 Freedom
2.4 , Fremont
7.4 ;„ ^Gilford
0.9 " " Gilmanton
2.2 "' Gilsum
6.8 Goffstown
4.5 Gorham
3.3 •• Goshen
3.0 ,/ Grantham
1.7 , ", Greenfield
35.5 Greenland
5.6 ..< .Greenville
19.9 ,-, Groton
2.5 - Hampstead
No. of Meas.
8
6
5
5
2
5
16
7
21
2
4
10
5
3
8
11
6
4
5
5
1
5
11
4
3
8
6
6
3
3
14
3
4
10
7
6
14
15
6
5
6
7
6
3
17
Mean
9.6
2.0
5.2
3.1
6.8
11:4
4.4
1..2
4.9
1.8
2.0
3.0
1.2
3.5
9.7
2.8
5.4
2.4
25.4
3.8
1.8
2.6
3.6
3.0
4.5
2.4
4.4
2.3
1.3
3.0
2.6
33.4
11.1
3.7
2.1
3.0
3.2 -
14.7
2.0
4.5
7.4
3.0
4.1
1.1
. 5.0.

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Table 1 (continued).
Town
Hampton
Hampton Falls
Hancock
Hanover
Harrisville
Hart's Location
Haverhill
Hebron
Henniker
Hill
Hillsboro
Hinsdale
Holderness
Hollis
Hooksett
Hopkinton
Hudson
Jackson
Jaffrey
Jefferson
Keene
Kensington
Kingston
Laconia
Lancaster
Landaff
Lebanon
Lee
Lempster
Lincoln
Lisbon
Litchfield
Littleton
Londonderry
Loudon
Lyman
Lyme
Lyndeborough
Madbury
Madison
Manchester
Marlborough
Marlow
Mason
Meredith
No. of Meas.
7
4
4
13
5
2
17
4
. 9
4
13
11
4
21
14
5
18
3
14
5
23
5
12
12
13-
2
27
3
5
1
5
18
13
15
5
4
3
8
5
5
38
7
2
6
12
Mean '-• Town
8;9 ^.Merrimack
4.8 - - Middleton
0.8 , v Milan
1.4 _ Milford
1.3 l\ Milton
266.6 >;r;« Monroe
4.3 " .V Mont Vernon
2.0 < < Moultonboro
1.6 ,%* Nashua
2.1 "' .Nelson
0.8 V" New Boston
2.0 < t New Castle
2.2 "^ \£ New Durham
7.3 ^ x , New Hampton
6.9 "; ' New Ipswich
0.9 - 'New London
5.5 t^Newbury
11.8 - ^£"Newington
2.6 ' " , Newmarket
1.8 -- ; Newport
1.7 V Newton
5.8 " / North Hampton
3.9 o Northfield
1 .8 " .- -, ;• -. Northumberland
2.9 / Northwood
1.0 " Nottingham
4.5 Orange
7.5 Orford
2.7 - Ossipee
1.3 -., Pelham
5.3 \ Pembroke
2.6 ""Peterborough .
2.2 ^ Piermont
7.8 v ^ Pittsburg
1.4 < Pittsfield
5.8 Plainsfield
2.5 "^-voPlaistow
4.8 ' V^- Plymouth
1 .9 Portsmouth
17.3 ' Randolph
5.1 / , Raymond
2.7 Richmond
2.5 Rindge
4.5 Rochester
1.7 Rollinsford
No. of Meas.
28
4
5
10
6
4
6
3
37
6
6
6
7
2
9
7
4
5
5
5
10
13
8
3
10
8
4
1
7
15
9
12
3
3
5
7
10
15
36
4
8
6
7
42
8
Mean
3.1
4.3
3.7
4.9
3.0
1.3
3.9
0.8
7.0
1.1
3.8
3.7
13.3
3.4
3.0
2.8
5.6
2.6
4.0
3.0
7.0
6.4
1.1
14.1 .
4.4
4.1
2.6
1.3
7.5
3.9
4.1
1.2
1.3
2.0
0.8
0.9
4.1
3.9
3.5
7.1
3.4
2.4
2.8
4.9
2.8

-------
Table 1 (continued).
Town
Roxbury
Rumney
Rye
Salem
Salisbury
Sanbornton
Sandown
Sandwich
Seabrook
Sharon
Shelburne
Somersworth
South Hampton
Springfield
Staric
Stewartstown
Stoddard
Strafford
Stratford
Stratham
Sugar Hill
Sullivan
Sunapee
Surry
Sutton
Swanzey
Tamworth
Temple
Thornton
Tilton
Troy
Tuftonboro •
Unity
Wakefield
Walpoie
Warner
Warren
Washington
Weare ,
Webster
Wentworth
Westmoreland
Whitefield
Wilmot
Wilton
No. of Meas.
2
7
13
19
4
. 4
7
2
7
7
7
8
5
4
4
3
5
7
4
10
4
3
5
7
5-
11
10
7
3
10
6
3
4
3
8
6
5
2
7
7
4
6
7
4
5
Mean ,,~ Town
1.6 -,,-< Winchester
6.8 Windham
7.0 " ^ , Windsor
2.6 , Wolfeboro
1.0 - ^Woodstock
0.8 •*,:*,
. 2.5 ^ '.
3.8 \J',
1.9 . .
6.3 :„ *
17.6 / I
4.5 - sS *;
6,1 ts* J'
1.5 _
17.1 ~*\V
2.9 \~;
0.7 """ ' *'
20.3 % ^^«
54.2 f.^s
6.2 •> \
1 q ^, ' '
'•« ,„. ^
1.4 ^:-;
1.5 ?"~
2.8 "+.--^
1.0 " ^
0.9 ^;^v
9.9 , ff
2.9 ^ -.:'
4.0 ,^^'
1.5 '' -
1.6 :f-r
2.2 s ,*-
1.0 ;v>
4.8 :;;,;-
2.4 • "•;;>
2.0
2.2 ^y;
1.1 ;-/'
1.9
1.0 ; :'
2.6 s^ ,r
1 .6
' •** -J: , vv
2.3
2.5 '"
3.2 % ,
No. of Meas.
5
16
1
9
4








































Mean
19.2
4.2
0.4
1.2
15.2









































-------
       10     20      30
             1      "*  miles
Figure 10. New Hampshire Counties (from Facts on File, 1984).

-------
 concentrations and is labile (Boudette, 1977). A sampling of 5,457 public and private water
 supplies by the New Hampshire Department of Environmental Services indicate that 20 percent of
 the water supplies tested had radon concentrations of 10,000 pCi/L or more (E. Boudette, pers.
 cornm., 1990). The amount of radon that is contributed to indoor air from water varies
 substantially and is related to the volume of air in the house and the volume of water used over a
 given period of time.

 TABLE 2. Radon-222 concentrations in ground water, by geologic formation (from Paulsen,
       1991, who derived the data from Hall and others, 1985; Hess and others,  1980; and Smith
       and others, 1961).
FORMATION
Kittery
Eliot
Berwick
Littleton
Exeter Diorite
Quartz diorite
Quartz monzonite
two-mica granite
Conway granite
Fitchburg Granite
# OF SAMPLES
10
12
20
11
10
3
14
11
15
2
AVERAGE (pO/L)
1,900
2,250
11,900
10,600
1,800
3,570
34,000
45,1000
22,370
284,000
GEOLOGIC RADON POTENTIAL

       The following discussion examines the above data in terms of geologic radon potential for
the land in New Hampshire. A numeric ranking is given in Table 3 and illustrated in figure 11.
Olszewsld and Boudette (1986) have compiled a generalized geologic map of New England with
emphasis on uranium endowment and radon production. Our analysis here corresponds very well
with their.uranium endowment map. We have adopted Olszewsld and Boudette's (1986)
geologic/geochemical divisions for figure 11.

A valoni an Terrane
     •  The Avalonian Composite Terrane has been ranked moderate to high in geologic radon
potential.  The Avalonian Composite Terrane is underlain by the Merrimack Group, Massabesic
Gneiss, the Rye Formation and several bodies of two-mica granites, alkalic plutonic rocks, and
mafic plutonic rocks.  Soils in this area have generally low permeability that is locally moderate to
high. The Merrimack Group has low to moderate equivalent uranium, whereas other rocks have
generally moderate to high equivalent uranium, particularly the Massabesic Gneiss and associated
faults.  Abundant faults and small granitic intrusions contribute to the overall high radon potential
of the Massabesic Gneiss and granitic rocks. Faults and fractures are often mineralized with
uranium in crystalline terranes and may cause locally anomalously high indoor radon (Gundersen,
1991) The Merrimack Group and Rye'Formation have overall moderate radon potential, with
locally low radon potential.  Average indoor radon for the townships underlain by Avalonian rocks
is predominantly moderate .(2-4 pCi/L) to high (> 4 pCi/L). Olszewsld and Boudette (1986)
                                         IV-26   Reprinted from USGS Open-FUe Report 93-292-A

-------
        RADON POTENTIAL
           HIGH
           MODERATE/VARIABLE
          LOW
Figure 11. Geologic radon potential areas of New Hampshire.

-------
 classified the Precambrian metasedimentary and metavolcanic rocks of the Merrimack group and
 the granitic gneiss of the Massabesic as having variable (low to high) uranium endowment They
 classified the two-mica granites as having high uranium endowment.

 The Gander and Boundary Mountains Terranes
       About half of New Hampshire is underlain by Cambrian-Devonian stratified metamorphic
 rocks of igneous or sedimentary origin that have been ranked moderate in radon potential.
 Olszewski and Boudette (1986) classified these Paleozoic metasedimentary and metavolcanic rocks
 as having variable uranium endowment, with increasing uranium as metamorphic grade increases,
 and with local uranium concentrations in fractures and faults. Uranium analyses for the
 metasedimentary and metavolcanic rocks (previously cited in the radioactivity section of this report)
 indicate uranium concentrations of less than 3 ppm in general. Graphitic slates, phyllites, and
 schists are known to be uranium sources in several areas of the Appalachians (Ratte and Vanacek,
 1980; Gundersen  and others, 1988) and this may be the case in New Hampshire. Where indoor
 radon data are available, the stratified metamorphic rocks appear to be associated with low to
 moderate indoor radon in the western portion of the State and with higher indoor radon in the
 eastern portion of the State and in the vicinity of plutonic rocks.  Soils developed on these rocks in
 low mountains and lowlands have generally low to moderate permeability. Intermediate to mafic
 plutonic rocks generally have low or variable radon potential. The Lake Winnipesaukee Quartz
 Diorite and the Kinsman Quartz Monzonite appear to have low equivalent uranium and low indoor
 radon associated with them. The Spaulding Quartz Diorite, from geologic arguments, might be
 considered low to moderate in radon potential, although the township indoor radon data appears
 moderate to high.  Several of the Oliverian domes have distinct radiometric highs associated with
 them (fig. 8) except for the northernmost and largest of the Oliverian rocks in the northern Gander
 Terrane, which have low radioactivity. Indoor radon in the townships underlying this area is
 variable from low to high.
       Two mica granites, calc-alkaline granites, and alkalic plutonic rocks in New Hampshire
 have been ranked  high in radon potential. Olszewski and Boudette (1986) classified these rocks as
 moderate to high in uranium endowment Uranium in these granites is commonly more than 3
 ppm and up to several hundred ppm.  Uranium occurs as primary uranium oxides such as uraninite
 or in abu,ndant accessory minerals. Two-mica granites occur throughout the central and eastern
 portions of New Hampshire. Calc-alkaline granites occur from east-central to northwestern New
 Hampshire. The largest body of calc-alkaline granite underlies the White Mountains and has very
 high radioactivity associated with it (fig. 8). Indoor radon in several townships in this area is high
 (fig. 9) and the soils usually have moderate permeability.

 SUMMARY

       For the purpose of this assessment, New Hampshire has been divided into 6 geologic
 radon potential areas and each area assigned a Radon Index (RI) and a Confidence Index (CI) score
 (Table 3). The RI is a semi-quantitative 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 book for more information). The geologic radon
potential areas are shown on a map of New Hampshire in figure  11.
                                          IV-28    Reprinted from USGS Open-File Report 93-292-A

-------
       This is a generalized assessment of the State's geologic radon potential and there is no
substitute for having a home tested. The cqnclusions about radon potential presented in this report
cannot be applied to individual homes or building sites.  Indoor radon levels, both high and low,
can be quite localized, and within any radon potential area there will likely be areas with higher or
lower radon potential than assigned to the area as a whole. Any local decisions about radon should
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-29   Reprinted from USGS Open-File Report 93-292-A

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 TABLE 3. RI and CI scores for geologic radon potential areas of New Hampshire.
FACTOR
INDOOR RADON
RADIOACTIVITY
GEOLOGY
SOIL PERM.
ARCHITECTURE
GFE POINTS
TOTAL
Massabesic
Gneiss
RI CI
3
3
2
2
3
0
13
3
2
3
3
-
-
11
Two Mica, calc-alkaline
and alkalic granites
RI CI
2
3
3
. 2
3
0
13
3
2
3
3
-
-
11
Oliverian and intermediate
composition plutonic
RI CI
2-
1
2
2
3
0
10
2
2
3
3
_
_
10
                    High  High
High   High
Mod   High
                LakeWinnepesaukee,      Stratified metamorphic        Merrimack Group
                Kinsman, and other       rocks, Gander and Boundary Mts. Rye Formation
              intermediate to mafic plutons
     FACTOR        RI    CI            RI     CI           RI     CI
INDOOR RADON
RADIOACTIVITY
GEOLOGY
SOIL PERM.
ARCHITECTURE
GFE POINTS
TOTAL
2
1
1
1
3
0
8
2
2
3
3
-
-
10
2
2
' 2
1
3
0
10
2
2
3
3
-
-
10
2
2
2
2
3 .
0
11
3
2
3
3
_
_
11
                    Low '  High
Mod   High
Mod   High
RADON INDEX SCORING:
Radon potential category
LOW
MODERATE/VARIABLE
HIGH
Point range
3-8 points '
9- 11 points
> 11 points
Probable screening indoor
radon average for area
<2pCi/L
2-4pCi/L
>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-30   Reprinted from USGS Open-File Report 93-292-A

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                        REFERENCES CITED IN THIS REPORT
      AND GENERAL REFERENCES RELEVANT TO RADON IN NEW HAMPSHIRE

 Bendix Field Engineering, 1982, National Uranium Resource Evaluation, Glen Falls Quadrangle,
       New York, Vermont, and New Hampshire: Prepared for the U.S. Department of Energy,
       Report PGJ/F-025(82), 31 p.

 Billings, M.P., 1955, Geologic map of New Hampshire: New Hampshire State Planning and
       Development Commission and the U.S. Geological Survey, scale 1:250,000.

 Billings, M.P., 1956, The geology of New Hampshire, part two, bedrock geology: New
       Hampshire State Planning and Development Commission, 1 plate, 203 p.

 Bothner, W.A., 1978, Selected uranium and thorium occurrences in New Hampshire: U.S.
       Geological Survey Open-File Report 78-482,43 p.

 Boudette, E.L., 1977, Two-mica granite and uranium potential in the northern Appalachian orogen
       of New England, in Cambell, J.A., ed., Short papers of the U.S. Geological Survey
       uranium-thorium symposium: U.S. Geological Survey Circular 753.

 Boudette, E.L.,  1990, The Geology of New Hampshire: Rocks and Minerals,v. 65, p. 306-312:

 Butler, A.P., Jr., 1975, Uranium and thorium in samples of rocks of the White Mountain plutonic
       series, New Hampshire, and whole-rock chemical and spectrographic analyses of selected
       samples: U.S. Geological Survey Open-File Report 75-59,17 p.

 Campisano, C.D. and Hall, F.R., 1986, Controls on radon occurrence in ground water; a small
       scale study in southeastern New Hampshire, in Aller, L., and Butcher, K., eds.,
       Proceedings of The Third Annual Eastern Regional Ground Water Conference,
       Springfield, MA, United States July 28-30, 1986, p. 638-649.

 Campisano, C.D.,  1988, Geochemical and hydrologic controls on radon-222 and radium-226 in
       ground water, in Proceedings of Ground water Geochemistry Conference,  Denver CO
       Feb. 16-18, 1988, p. 23-52.

 Chapman, D.H., 1976, Physical divisions of New Hampshire, in Randall, P. E., ed., New
       Hampshire's Land: Hanover, N.H., Profiles Publishing Corp., p. 28-29.

 Chiasma Consultants, Inc., 1982, National Uranium Resource Evaluation, Portland Quadrangle,
       Maine and  New Hampshire: Prepared for the U.S. Department of Energy Report
       PGJ/F-028(82), 28 p.

Denny, C.S., 1982, Geomorphology of New England:  U.S. Geological Survey Professional
      Paper 1208, 18 p.

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.

Facts on File, 1984, State Maps on File, New England.
                                        IV-31   Reprinted from USGS Open-File Report 93-292-A

-------
Flint, R.F, Colton, R.B., Goldthwait, R.P., and Willman, H.B. (compilers), 1959, Glacial map
       of the United States east of the Rocky Mountians:  Geological Society of America Map and
       Chart Series MC-1, scale 1:750,000.

Goldthwait, J.W., Goldthwait, L., and Goldthwait, R.P., 1950, Surficial geology of New
       Hampshire:  New Hampshire State Planning and Development Commission, scale
       1:250,000.

Goldthwait, J.W., Goldthwait, L., and Goldthwait, R.P., 1951, The geology of New Hampshire,
       Part I—surficial geology: Concord, N.H., New Hampshire State Planning and
       Development Commission, 84 p.

Gundersen, L.C.S., Reimer, G.M., Wiggs, C.R., and Rice, C.A., 1988, Radon Potential of
       Rocks and Soils in Montgomery County Maryland; U.S. Geological Survey
       Miscellaneous Field Studies Map 88-2043, scale 1:62,500.

Gundersen, L.C.S., 1991, Radon in sheared metamorphic and igneous rocks: in Gundersen,
       L.C.S., and Wanty R.B., eds., Geologic and Geochemical Field  Studies of Radon in
       Rocks, Soils, and Water;  U.S. Geological Survey Bulletin 1971, p. 38-49.

Hall, F.R., Boudette, E.L. and OlszewsM, W.J., Jr., 1987, Geologic controls and radon
       occurrence in New England, in Graves, B., ed., Radon, radium, and other radioactivity in
       ground water: Chelsea, Mich., Lewis Publishers, p. 15-30.

Hall, F.R., Boudette, E.L., and Olszewski, W.J., Jr., 1987, Geologic controls and radon in New
       England, in Graves, B., ed., Radon in ground water:  Chelsea, Mich., Lewis Publishers,
       p. 227-240.

Hall, F.R., Donahue, P.M., and Eldridge, A.L., 1985, 222Rn gas in ground water of New
       Hampshire, in Proceedings of the Association of Ground Water Scientists and Engineers,
       Second Annual Eastern Regional Ground Water Conference: Dublin, Ohio, National Water
       Well Association, p. 86-101.

Hatcher,'R.D., Jr., Thomas, W.A., and Viele, G.W., eds.,. 1989, The Appalachian-Ouachita
       Orogen in the United States: Geological Society of America, Geology of North America,
       v.F-2,  767 p.

Hess, C.T., Korsah, J.K., and Einloth, C.J.,  1986, 222Rn in homes  due  to 222Rn in potable
       water, in Hopke, P.K., ed., Radon and its decay products—Occurrence, properties, and
       health effects: American Chemical Society Symposium 331, p. 30-41.

Hess, C.T., Norton, S.A., Brutseart, W.F.,  Casparius, R.E., Coombs,  J., E. and Hess, A.L.,
       1980, Radon-222 in potable water supplies of New England: Journal of the New England
       Water Works Association, v. 94, p. 113-128.

Hoisington, W.D., 1977, Uranium and thorium distribution in the Conway Granite of the White
       Mountain Batholith:  Hanover, N.H., Dartmouth College, unpublished M.S. thesis, 120 p.

Jaupert, C, Mann, J.R., and Simmons, G., 1982, A detailed study of heat flow and radioactivity
       in New Hampshire (U.S.A.):  Earth and-Planetary Science Letters, v. 59, p. 267-287.
                                         IV-32   Reprinted from USGS Open-File Report 93-292-A

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Koch, T.J., Gust, D.A. and Lyons, W.B., 1988, Geochemistry of radon-rich waters from two-
       mica granites, in FOCUS: Proceedings of Conference on Eastern regional ground water
       issues Stamford, CT, Sept. 27-29, 1988, p. ;587-601.

Koteff, C, and Pessl, R, Jr., 1985, Till stratigraphy in New Hampshire:  Correlations with
       adjacent New England and Quebec, in Borns, H.W., Jr., Lasalle, P., and Thompson,
       W.B., eds, Late Pleistocene history of northeastern New England and adjacent Quebec:
       Geological Society of America Special Paper 197, p. 1-12.

Lyons, J.B., 1964, Distribution of thorium and uranium in three early Paleozoic plutonic series of
       New Hampshire: U.S. Geological Survey Bulletin 144-F, 43 p.

Lyons, J.B., Boudette, E.L., and Aleinikoff, J.N., 1982, The Avolonian and Gander zones in
       Central eastern new England, in StJulien, P. and Beland, J., eds., Major structural zones
       and faults of the northern Appalachians: Geological Association of Canada Special Paper
       24, p. 43-66.

Lyons, J.B., Bothner, W.A., Moench, R.H., and Thompson, J.B., eds., 1986, Interim geologic
       map of New Hampshire: New Hampshire Geological Survey Open-File map 86-1, scale
       1:250,000.

Lyons, W.B. and Gust, D.A., 1988, The generation of Cl - in ground waters from granite in New
       Hampshire and its role in the mobilization of naturally occurring radionuclides, in Fiscal
       year  1987 program report:  U. S. Geological Survey, p. 14-15.

National Oceanic and Atmospheric Administration, 1974, Climates of the states, volume I-Eastern
       states:  U.S. Department of Commerce, published by Water Research Information Center,
       Inc.,  Port Washington, NY.

Nazaroff, W.W., and Nero, A.V., Jr., 1988, Radon and its decay products in indoor air: New
       York, John Wiley and Sons, 518 p.

New Hampshire Department of Environmental Services,  1989, State of New Hampshire
       Geological Publications, 10 p.

Olszewski, W.J., Jr., and Boudette, E.L,, 1986, Generalized bedrock geologic map of New
      England with emphasis on uranium endowment and radon production:  U.S.
      Environmental Protection Agency Open-File Map.

Paulsen, R.T., 1988, Radionuclides in ground waters of the northeastern United States and
      southern Canada; a literature review and summary: Northeastern' Environmental Science,
      v. 7,  p. 8.

Paulsen, R.T., 1991, Radionuclides in ground water, rock and soil, and indoor air of the
      northeastern United States and southeastern Canada—A literature review and summary of
      data, in Gundersen, L.C.S., and Wanty, R.B., eds., Field studies of radon in rocks, soils,
      and water: U.S. Geological Survey Bulletin 1971, p. 195-225.

Pilgrim, S.A.L., and Peterson, N.K.,  1979, Soils of New Hampshire:  University of New
      Hampshire Agricultural Experiment Station Research Report 79,79 p.
                                         IV-33    Reprinted from USGS Open-File Report 93-292-A

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Pirie, J.C., and Hannington, I.E., 1989, New Hampshire radon survey 1987-1988 (with
       Addendum: New Hampshire radon survey 1987-1990): New Hampshire Division of
       Public Health Services, Report 89-015.

Ratte", C., and Vanacek, D., 1980, Radioactivity Map of Vermont: Vermont Geological Survey,
       File No., 1980-1, rev. 3,3 plates with text.

Richmond, G.M., and Fullerton, D.S., eds, 1987, Quaternary geologic map of the Quebec 4° x 6°
       quadrangle, United States and Canada: U.S. Geological Survey Miscellaneous
       Investigations Map 1-1420, sheet NL-19, scale 1:1,000,000.                   '    .

Richmond, G.M., and Fullerton, D.S., eds, 1991, Quaternary geologic map of the Boston 4° x 6°
       quadrangle, United States and Canada: U.S. Geological Survey Miscellaneous
       Investigations Map 1-1420, sheet NK-19, scale 1:1,000,000.

Richmond, G.M., and Fullerton, D.S., eds, 1992, Quaternary geologic map of the Hudson River
       4° x 6° quadrangle, United States and Canada: U.S. Geological Survey Miscellaneous
       Investigations Map 1-1420, sheet NK-18, scale 1:1,000,000.

Roy, R.F., Blackwell, D.D., and Birch, F., 1968, Heat generation of plutonic rocks and
       continental heat flow provinces: Earth and Planetary Science Letters, v. 5, p. 1-12.

Smith, B.M., Grune, W.N., Higgins, F.B., and Terrill, J.G., Jr., 1961, Natural radioactivity in
       ground water supplies in Maine and New Hampshire: Journal of the American Water
       Works Association, v. 53, p. 75-88.

Stone, B.D., and Borns, H.W., Jr., 1986, Pleistocene glacial and interglacial stratigraphy of New
       England, Long Island, and adjacent Georges Bank and Gulf of Maine, in Sibrava, V.,
       Bowen, D.Q., and Richmond, G.M., eds., Quaternary Glaciations in the Northern
       Hemisphere:  Quaternary Science Reviews, v. 5, p. 39-52.

U.S. Soil Conservation  Service, 1987, Soils: U.S. Geological Survey National Atlas sheet
       38077-BE-NA-07M-00, scale 1:7,500,000.

Wathen, J.B., and Hall, F.R., 1986, Factors affecting levels of Rn-222 in wells drilled into two-
       mica granites in Maine and New Hampshire, in Aller, L., and Butcher, K., eds.,
       Proceedings of The Third Annual Eastern Regional Ground Water Conference,
       Springfield, MA, July 28-30, 1986, p. 650-681.

Wathen, J.B., 1987, The effect of uranium siting in two-mica granites on uranium concentrations
       and radon activity in ground water, in Graves, B., ed., Radon, radium, and other
       radioactivity in ground water: Chelsea, Mich., Lewis Publishers, p. 31-46.
                                         IV-34    Reprinted from USGS Open-File Report 93-292-A

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                           EPA's Map of Radon Zones
       The USGS1 Geologic Radon Province Map' is the technical foundation for EPA's Map
of Radon Zones.  The Geologic Radon Province Map defines the radon potential for
approximately 360 geologic provinces. EPA has adapted this information to fit a county
boundary map in order to produce the Map of Radon Zones.
       The Map of Radon Zones is based on the same range of predicted screening levels of
indoor radon  as USGS' Geologic Radon Province  Map.  EPA defines the three zones as
follows:  Zone One areas, have an average predicted indoor radon screening potential greater
than 4 pCi/L.  Zone Two areas are predicted to  have an  average indoor radon screening
potential between  2 pCi/L and 4 pCi/L.  Zone Three areas are predicted to have an average
indoor radon  screening potential less than 2 pCi/L.
       Since  the geologic province boundaries cross state and  county boundaries,  a strict
translation of counties from the Geologic Radon Province Map to the Map of Radon  Zones
was not possible.  For counties that have variable  radon  potential (i.e.,  are located in  two or
more provinces of different rankings), the counties were assigned to  a zone based on  the
predicted radon potential of the province in which most  of its  area lies. (See Part I for more
details.)
NEW HAMPSHIRE MAP OF RADON ZONES

       The New Hampshire Map of Radon Zones and its supporting documentation (Part IV
of this report) have received extensive review by New Hampshire geologists and radon
program experts.  The map for New Hampshire 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 Hampshire" — 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 1 EPA office or the
New Hampshire radon program for information on testing and fixing homes.  Telephone
numbers and addresses can be found in Part II of this report.
                                         V-l

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