Preliminary Lithogeochemical Map Showing Near-Surface Rock Types in the Chesapeake Bay Watershed, Virginia and Maryland

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What does this data set describe?

Title:
Preliminary Lithogeochemical Map Showing Near-Surface Rock Types in the Chesapeake Bay Watershed, Virginia and Maryland
Abstract:
This preliminary experimental lithogeochemical map shows the distribution of rock types in the Virginia and Maryland parts of the Chesapeake Bay watershed. The map was produced digitally by classifying geologic-map units according to composition, mineralogy, and texture; rather than by age and stratigraphic relationships as shown on traditional geologic maps. This map differs from most lithologic maps in that the lithogeochemical unit classification distinguishes those rock units having key water-reactive minerals that may induce acid neutralization, or reduction, of hosted water at the weathering interface. The validity of these rock units, however, is independent of water chemistry, because the rock units are derived from geologic maps and rock descriptions. Areas of high soil carbon content, and sulfide metal deposits are also shown.
Water-reactive minerals and their weathering reactions yield five lithogeochemical unit classes: 1) carbonate rock and calcareous rocks and sediments, the most acid-neutralizing; 2)carbonaceous-sulfidic rocks and sediments, oxygen-depleting and reducing; 3) quartzofeldspathic rocks and siliciclastic sediments, relatively weakly reactive with water; 4) mafic silicate rocks/sediments, oxygen consuming and high solute-load delivering; and, 5) the rarer calcareous-sulfidic (carbonaceous) rocks, neutralizing and reducing. Earlier studies in some parts of the map area have related solute loads in ground and stream waters to some aspects of bedrock lithology. More recent preliminary tests of relationships between four of the classes of mapped lithogeochemical units and ground water chemistry, in the Mid-Atlantic area using this map, have focused on and verified the nitrate-reducing and acid-neutralizing properties of some bedrock and unconsolidated aquifer rock types. Sulfide mineral deposits and their mine-tailings effects on waters are beginning to be studied by others. Additional testing of relationships among the lithogeochemical units and aspects of ground and surface water chemistry could help to refine the lithogeochemical classification, and this map. The testing could also improve the usefulness of the map for assessing aquifer reactivity and the transport properties of reactive contaminants such as acid rain, and nitrate from agricultural sources, in the Chesapeake Bay watershed.
Supplemental_Information:
Data were originally collected in UTM coordinates, zone 18, NAD 1927, and projected to geographic coordinates (Lat/Long), NAD 1983. The data base is accompanied by a large format color map, a readme.txt file, and a explanatory PDF pamphlet.
  1. How might this data set be cited?
    Peper, John D., McCartan, Lucy B., J. Wright Horton, Jr., and Reddy, James E., 2001, Preliminary Lithogeochemical Map Showing Near-Surface Rock Types in the Chesapeake Bay Watershed, Virginia and Maryland: U.S. Geological Survey Open-File Report 01-187, U.S. Geological Survey, Reston, Virginia.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -80.75
    East_Bounding_Coordinate: -75.00
    North_Bounding_Coordinate: 39.75
    South_Bounding_Coordinate: 36.50
  3. What does it look like?
    http://pubs.usgs.gov/of/2001/of01-187/01187p1p.gif (GIF)
    Reduced-size image showing the general layout of map sheet. 864x597 pixels, 24-bit color.
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 1995
    Ending_Date: 2001
    Currentness_Reference:
    Publication date
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: Map
  6. How does the data set represent geographic features?
    1. How are geographic features stored in the data set?
      This is a Vector data set. It contains the following vector data types (SDTS terminology):
      • Entity point
      • Complete chain
      • GT-polygon composed of chains
    2. What coordinate system is used to represent geographic features?
      Horizontal positions are specified in geographic coordinates, that is, latitude and longitude. Latitudes are given to the nearest 0.001. Longitudes are given to the nearest 0.001. Latitude and longitude values are specified in Decimal degrees. The horizontal datum used is North American Datum of 1983.
      The ellipsoid used is Geodetic Reference System 80.
      The semi-major axis of the ellipsoid used is 6378137.
      The flattening of the ellipsoid used is 1/298.257.
  7. How does the data set describe geographic features?
    Entity_and_Attribute_Overview:
    The following is a brief description of the data layers, tables, and their associated attributes that are used in this report.
    
    GEOLOGIC DATA:
    CARBON - polygon data layer of carbon-rich soils:
      MUID - map unit identifier derived from STATSGO data base
      OC.M.G.M2 - value for soil organic carbon in square meters
    
    GEOLOGY - polygon data layer of the contacts of geologic map units:
      GEOL_CODE - geologic map unit code
    
    LITHOGEO - polygon data layer of the contacts of lithogeochemical map units:
      LITH_CODE - lithogeochemical map unit code
    
    SULFIDE - point data layer of sulfide deposits:
      STATE_CODE - state code
      SITE - deposit name
      LAT - latitude
      LONG - longitude
      COMMOD - commodities present
      MAJOR - major products
      MINOR - minor products
      TRACE - trace or occurrence commodity
      DEP_TYPE - deposit types
      MODEL - USGS model name
      DEP_SIZE - size of deposit
    
    GEOLLITH - data table that relates GEOL_CODE to LITH_CODE:
      GEOL_CODE - geologic map unit code
      LITH_CODE - lithogeochemical map unit code
    
    LITHTBL - data table that relates LITH_CODE to ROCK_TYPE_GROUP, SUB_GROUP, MAP_UNIT, ROCK_TYPE_CLASS, MINERALOGY, and WATER_CHEMISTRY:
      LITH_CODE - lithogeochemical map unit code
      ROCK_TYPE_GROUP - rock type; e.g., sedimentary rocks and their metamorphic equivalents
      SUB_GROUP - rock type sub group; e.g., carbonate-rich rock
      MAP_UNIT - map unit; e.g., limestone
      ROCK_TYPE_CLASS -  rock class; e.g., carbonate-bearing rock
      MINERALOGY - mineralogical properties; e.g., quartz-, and feldspar-rich rock
      WATER_CHEMISTRY - suggested water chemistry; e.g., low acid-neutralizing capacity
    
    BASE DATA:
    POLBND - polygon data layer of county boundaries:
      STATECTY - map unit identifier derived from the Chesapeake Bay Program data
      ST - state identifier
      CNTYNAME - county name
      POLYTYPE - feature identifier derived from the Chesapeake Bay Program data
    
    Entity_and_Attribute_Detail_Citation: http://pubs.usgs.gov/of/2001/of01-187/of01187.pdf

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • John D. Peper
    • Lucy B. McCartan
    • J. Wright Horton, Jr.
    • James E. Reddy
  2. Who also contributed to the data set?
  3. To whom should users address questions about the data?
    J. Wright Horton, Jr.
    U.S. Geological Survey
    National Center, MS926A
    Reston, Virginia
    USA

    703-648-6933 (voice)
    703-648-6953 (FAX)
    whorton@usgs.gov

Why was the data set created?

The purpose of this preliminary digital map is to provide a geographically referenced data base showing regional patterns in the distribution of rock types in the Virginia and Maryland parts of the Chesapeake Bay watershed. The map may be used to evaluate the hypothesis that lithology of rocks and sediments significantly influences the chemistry and quality of waters traveling over and through them on a regional scale.

How was the data set created?

  1. From what previous works were the data drawn?
    Cleaves (1968) (source 1 of 6)
    Cleaves and others, 1968, Geologic Map of Maryland.

    Online Links:

    Type_of_Source_Media: Paper map
    Source_Scale_Denominator: 250000
    Source_Contribution:
    Provided geology for Maryland. Used to produce digital polygon data of Maryland geology.
    Virginia Division of Mineral Resources (1993) (source 2 of 6)
    Virginia Division of Mineral Resources, 1993, Geologic Map of Virginia.

    Type_of_Source_Media: Paper map
    Source_Scale_Denominator: 500000
    Source_Contribution:
    Provided geology for Virginia. Used to produce digital polygon data of Virginia geology.
    STATSGO Maryland (1994) (source 3 of 6)
    U.S. Department of Agriculture, Soil Conservation Service, 1994, State Soil Geographic (STATSGO) data base for Maryland.

    Type_of_Source_Media: Digital general soil association map
    Source_Scale_Denominator: 250000
    Source_Contribution:
    Provided soil data for Maryland. Used to produce digital polygon data of Maryland carbon-rich soils.
    STATSGO Virginia (1994) (source 4 of 6)
    U.S. Department of Agriculture, Soil Conservation Service, 1994, State Soil Geographic (STATSGO) data base for Virginia.

    Type_of_Source_Media: Digital general soil association map
    Source_Scale_Denominator: 250000
    Source_Contribution:
    Provided soil data for Virginia. Used to produce digital polygon data of Virginia carbon-rich soils.
    MRDS (1998) (source 5 of 6)
    Lipin, B., Mason, Jr., George T., and McFaul, E.J., 1998, Mineral Resources Data System (MRDS) Release-2: U.S. Geological Survey Digital Data Series DDS-20 Release-2, U.S. Geological Survey, Reston, VA.

    Type_of_Source_Media: Digital records of metallic and nonmetallic mineral resources
    Source_Contribution:
    Provided sulfide data for Maryland and Virginia. Used to produce digital point data of Maryland and Virginia sulfide deposits.
    CBP (source 6 of 6)
    Program, Chesapeake Bay, 1998, Mid-Atlantic States County Boundaries.

    Type_of_Source_Media: Arc/Info coverage
    Source_Scale_Denominator: 100000
    Source_Contribution:
    Provided base map data. Used to produce polygon coverages of county boundaries for Maryland and Virginia
  2. How were the data generated, processed, and modified?
    Date: 2001 (process 1 of 6)
    Geology was mapped by Cleaves and others and published in 1968. The geologic map was scanned using an Anatech Eagle 4080T scanner. The raster files were then converted to Abicas map image format and the geologic information was digitized as 30' x 60' tiles. The Abicas files were converted to Arc/Info format. Arc/Info versions 7.2.1 and 8.0.2 were used to assemble the individual tiles into a statewide geologic coverage containing geologic and lithogeochemical attributes. The statewide coverage was clipped to the Chesapeake Bay Watershed boundary. Digital compilation was completed in 2001. The Arc/Info coverage was converted to Abicas, Arc/Info export-interchange, and ArcView shapefile formats. Person who carried out this activity:
    Maryland Geological Survey
    2300 St. Paul Street
    Baltimore, MD

    (410) 554-5500 (voice)
    Date: 2001 (process 2 of 6)
    Geology was mapped by the Virginia Division of Mineral Resources and published in 1993. The geologic map was scanned using an Anatech Eagle 4080T scanner. The raster files were then converted to Abicas map image format and the geologic information was digitized as 30' x 60' tiles. The Abicas files were converted to Arc/Info format. Arc/Info versions 7.2.1 and 8.0.2 were used to assemble the individual tiles into a statewide geologic coverage containing geologic and lithogeochemical attributes. The statewide coverage was clipped to the Chesapeake Bay Watershed boundary. Digital compilation was completed in 2001. The Arc/Info coverage was converted to Abicas, Arc/Info export-interchange, and ArcView shapefile formats. Person who carried out this activity:
    Virginia Department of Mines, Minerals and Energy; Division of Mineral Resources
    P.O. Box 3667
    Charlottesville, VA

    (804) 951-6340 (voice)
    Date: 1998 (process 3 of 6)
    STATSGO data base was compiled by the U.S. Department of Agriculture, Soil Conservation Service and published in 1994. Arc/Info version 7.1.2 was used to create an INFO table named OC13MAPUNIT from the data base. The table OC13MAPUNIT contains, for each soil map unit (MUID) in Maryland, a value of the soil organic carbon in the total soil profile. This value is stored in an item named OC.M.G.M2 (for organic carbon, mapunit, grams, meters squared). The Arc/Info command JOINITEM was used to add the item OC.M.G.M2 to the .pat table for the CARBON coverage. The Arc/Info coverage was converted to Abicas, Arc/Info export-interchange, and ArcView shapefile formats.
    Date: 1998 (process 4 of 6)
    STATSGO data base was compiled by the U.S. Department of Agriculture, Soil Conservation Service and published in 1994. Arc/Info version 7.1.2 was used to create an INFO table named OC13MAPUNIT from the data base. The table OC13MAPUNIT contains, for each soil map unit (MUID) in Virginia, a value of the soil organic carbon in the total soil profile. This value is stored in an item named OC.M.G.M2 (for organic carbon, mapunit, grams, meters squared). The Arc/Info command JOINITEM was used to add the item OC.M.G.M2 to the .pat table for the CARBON coverage. The Arc/Info coverage was converted to Abicas, Arc/Info export-interchange, and ArcView shapefile formats.
    Date: 1998 (process 5 of 6)
    MRDS data base was compiled by the U.S. Geological Survey between 1972 and 1998 and published in 1998. Arc/Info version 7.1.2 was used to create Maryland and Virginia statewide point coverages from the MRDS data base. The statewide coverages were clipped to the Chesapeake Bay Watershed boundary to create the SULFIDE coverages. The Arc/Info coverages were converted to Abicas, Arc/Info export-interchange, and ArcView shapefile formats.
    Date: 1998 (process 6 of 6)
    Digital Line Graph (DLG) files of county boundaries at 1:100,000-scale were created by the U.S. Geological Survey as 15' x 15' tiles. The Chesapeake Bay Program used the USGS DLG files to create a Mid-Atlantic States County Boundaries data layer in Arc/Info coverage format. The Mid-Atlantic regional coverage was obtained from http://www.chesapeakebay.net/data/index.htm and clipped to the Chesapeake Bay Watershed boundary to create the POLBND coverages for Maryland and Virginia. The Arc/Info coverages were converted to Abicas, Arc/Info export-interchange, and ArcView shapefile formats.
  3. What similar or related data should the user be aware of?

How reliable are the data; what problems remain in the data set?

  1. How well have the observations been checked?
  2. How accurate are the geographic locations?
  3. How accurate are the heights or depths?
  4. Where are the gaps in the data? What is missing?
    All lithogeochemical polygons in this report were derived from digitized Maryland and Virginia state geologic maps. Digital compilation of the Virginia geologic data was completed in 1998. Subsequent to the beginning of this study, the Virginia Division of Mineral Resources completed a revision of the data set. However, the Virginia geologic data used to prepare this report was taken from the earlier data set.
  5. How consistent are the relationships among the observations, including topology?
    Polygon and chain-node topology present

How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?
Access_Constraints: None
Use_Constraints:
Although all data released in this report have been used by the USGS, no warranty, expressed or implied, is made by the USGS as to the accuracy of the data and related materials and (or) the functioning of the software. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government
  1. Who distributes the data set? (Distributor 1 of 1)
    U.S. Geological Survey
    J. Wright Horton, Jr.
    National Center, MS926A
    Reston, Virginia
    USA

    703-648-6933 (voice)
    703-648-6953 (FAX)
    whorton@usgs.gov
    Hours_of_Service: Monday - Friday 9:00 - 5:00 EST
  2. What's the catalog number I need to order this data set? USGS Open-File Report 01-187
  3. What legal disclaimers am I supposed to read?
    These data were prepared by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, make any warranty, expressed or implied, or assume any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product or process disclosed in this report, and represents that its use would not infringe privately owned rights. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the USGS in the use of this data or related materials. Reference therein to any specific commercial product, process, or related service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof.
  4. How can I download or order the data?
    • Availability in digital form:
      Data format: Geologic and lithogeochemical contacts, carbon-rich soils, sulfide deposits, and county boundaries in format ARCE (version 8.0.2) Size: 7.0
      Network links: http://pubs.usgs.gov/of/2001/of01-187/of01187.zip
    • Cost to order the data: none


Who wrote the metadata?

Dates:
Last modified: 13-Jun-2016
Metadata author:
U.S. Geological Survey
James E. Reddy
30 Brown Road
Ithaca, New York
USA

607-266-0217, x3014 (voice)
607-266-0521 (FAX)
jreddy@usgs.gov
Hours_of_Service: Monday - Friday 9:00 - 5:00 EST
Metadata standard:
Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)
Metadata extensions used:

This page is <https://geo-nsdi.er.usgs.gov/metadata/open-file/01-187/metadata.faq.html>
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