WELLSITE: Bedrock Data from Western Cape Cod, Massachusetts

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Frequently-anticipated questions:

What does this data set describe?

    Title: WELLSITE: Bedrock Data from Western Cape Cod, Massachusetts
    Cores collected from recent drilling in western Cape Cod, Massachusetts provide insight into the topography and petrology of the underlying bedrock. Cores from 64 drill sites spread over a ~140 km2 study area produced samples of granitoids (31), orthogneisses (20), basalts/diabases (4), amphibolites (3), felsic mylonites (2), and dolomitic rock (2).

    Granitoid composition ranges from granite to tonalite and quartz diorite, but it is dominated by two-feldspar granites. Hydrothermal alteration is common in nearly all cores as evidenced by the secondary growth of chlorite and epidote. Granitoids resemble rocks of the Dedham and Fall River plutons (Wones and Goldsmith, 1991). Gneisses generally contain the mineral assemblage K-feldspar+plagioclase+quartz±biotite± chlorite±muscovite±sphene±epidote+oxides. Amphibolites contain the assemblage hornblende+plagioclase+quartz+biotite+epidote±chlorite±sphene±K-feldspar±sericite+ oxides. Peak metamorphic grade based on mineral assemblages is estimated at lower amphibolite facies. X-ray powder diffraction of unmetamorphosed dolomitic cores shows presence of layered silicates (clays), plagioclase, and possible magnesite.

    Contours of the bedrock surface show locally irregular topography suggesting erosion by glacial scour. Lithologic distribution mapping suggests a possible continuation of the New Bedford gneissic terrane that outcrops 25 km to the west. Dolomitic rocks may represent a lithified fault gauge material at the eastern edge of the gneissic zone. Basalts/diabases are interpreted to be post-metamorphic dikes associated with Mesozoic rifting.

  1. How should this data set be cited?

    U.S. Geological Survey, 20030505, WELLSITE: Bedrock Data from Western Cape Cod, Massachusetts:, U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole, MA.

    Online Links:

    This is part of the following larger work.

    Hallett, B.W., Paskevich, V.F., Poppe, L.J., Brand, S.G., and Blackwood, D.S., 2003, A Pictorial Survey of the Bedrock Beneath Western Cape Cod, Massachusetts: Open File Report 03-221, U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole Field Center, Woods Hole, MA.

    Online Links:

    Data is released via CD-ROM media. This digital publication may also be available via the web at pubs.usgs.gov

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -70.615932
    East_Bounding_Coordinate: -70.501960
    North_Bounding_Coordinate: 41.667870
    South_Bounding_Coordinate: 41.611070

  3. What does it look like?

    wellsite (GIF)
    Image showing the distribution of the wellsite locations in Western Cape Cod, Massachusetts.

  4. Does the data set describe conditions during a particular time period?

    Calendar_Date: 2004
    Currentness_Reference: publication date

  5. What is the general form of this data set?

    Geospatial_Data_Presentation_Form: vector digital data

  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 (64)

    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 0.00001. Longitudes are given to the nearest 0.000001. Latitude and longitude values are specified in Decimal degrees.

      The horizontal datum used is North American Datum of 1927.
      The ellipsoid used is Clarke 1866.
      The semi-major axis of the ellipsoid used is 6378206.400000.
      The flattening of the ellipsoid used is 1/294.978698.

      Altitude_Datum_Name: National Geodetic Vertical Datum of 1929
      Altitude_Resolution: 0.01
      Altitude_Distance_Units: m
      Depth_Datum_Name: Mean sea level
      Depth_Resolution: 0.01
      Depth_Distance_Units: meters

  7. How does the data set describe geographic features?

    Shapefile Attribute Table (Source: ESRI)

    Internal feature number. (Source: ESRI)

    Sequential unique whole numbers that are automatically generated.

    Feature geometry. (Source: ESRI)

    Coordinates defining the features.

    Names assigned to designate the wellsite location. (Source: CH2M Hill Scientist)

    Name of wellsite location (characters and numerics)

    Latitude coordinate of well location (Source: CH2M Hill scientist)

    Range of values
    Units:decimal degrees

    Longitude coordinate of well location (Source: CH2M Hill Scientist)

    Range of values
    Units:decimal degrees

    Elevation of wellsite (ground level) above mean sea level (Source: CH2M Hill Scientist)

    Range of values

    Elevation (depth) of the upper bedrock surface below mean sea level (Source: CH2M Hill Scientist)

    Range of values

    Elevation of the top of casing above mean sea level. (Source: CH2M Hill Scientist)

    Range of values

    Total thickness of strata penetrated by the well (Source: CH2M Hill Scientist)

    Range of values

    Date well was completed (Source: CH2M Hill)

    Dates in yy/mm/dd notation

    Brief description of the rock type (Source: USGS Scientist)

    Quartz Diorite 
    Quartz Monzonite 
    Dolomitic Mudrock 
    Felsic Mylonite 
    Syenitic Mylonite 

    Name of the bedrock picture in .jpg format, and the path to that image on the CD-ROM (Source: Scientist)

    Character string: Photo names and paths

    Path to bedrock photo used as hotlink field in ArcView project file. (Source: User Defined)

    Character string: system environment label and photo name

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)

  2. Who also contributed to the data set?

    Jacobs Engineering for drilling the wells, S. Brand of CH2M Hill and the Air Force Center for Environmental Excellence for providing access to the well samples and logs, B. Hallett for the petrographic descriptions, and L. Poppe for creating the ArcView shapefile.

  3. To whom should users address questions about the data?

    Lawrence J. Poppe
    U.S. Geological Survey
    U.S. Geological Survey
    Woods Hole, MA 02543-1598

    (508) 548-8700 x2314 (voice)
    (508) 457-2310 (FAX)

Why was the data set created?

The purpose of this data layer is to provide those interested in the composition and character of the bedrock beneath western Cape Cod with the ability to examine the well logs and sample descriptions in a geographic context.

How was the data set created?

  1. From what previous works were the data drawn?

    (source 1 of 1)
    , Unpublished Material.

    Type_of_Source_Media: disc

  2. How were the data generated, processed, and modified?

    Date: 05-May-2003 (process 1 of 1)
    The well identifiers, navigation, and bedrock descriptions were compiled in Microsoft Excel and saved as an ASCII text file. The ASCII text file was imported to an ArcView table. The table was later converted to an Event Theme in ArcView and saved as the final shapefile.

    Person who carried out this activity:

    Lawrence J. Poppe
    U.S. Geological Survey
    U.S. Geological Survey
    Woods Hole, MA 02543-1543

    (508) 548-8700 x2314 (voice)
    (508) 457-2310 (FAX)

    Data sources used in this process:
    • wellsite.txt

    Data sources produced in this process:

    • wellsite.shp
    • wellsite.dbf
    • wellsite.shx

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

  1. How well have the observations been checked?

    All attributes were checked in a consistent manner.

  2. How accurate are the geographic locations?

    Each wellsite was surveyed; horizontal accuracy to less than 1 meter.

  3. How accurate are the heights or depths?

    Each wellsite was surveyed; vertical accuracy to less than 1 meter.

  4. Where are the gaps in the data? What is missing?

    This data set contains a subset of the wells drilled on the Massachusetts Military Reservation and a subset of the attributes available in the database from this drilling program maintained as part of the Installation Restoration Program there. This data set contains station locations, navigation, well information, and lithologies of the bedrock for 64 locations, 57 of which have associated images.

  5. How consistent are the relationships among the observations, including topology?

    No additional checks for topological consistency were performed on this data.

How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?

Access_Constraints: None
Public domain data from the U.S. government are freely redistributable with proper metadata and source attribution. The USGS must be referenced as the originator of this data set.

  1. Who distributes the data set? (Distributor 1 of 1)

    U.S. Geological Survey
    c/o Lawrence J. Poppe
    U.S. Geological Survey
    Woods Hole, MA 02543

    508-457-2314 (voice)
    508-457-2310 (FAX)

  2. What's the catalog number I need to order this data set?

    Logs and descriptions of the bedrock for wells completed on the Upper Cape, Massachusetts.

  3. What legal disclaimers am I supposed to read?

    Although this data set has been used by the U.S. Geological Survey, no warranty, expressed or implied, is made by the USGS as to the accuracy of the data and/or related materials. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the USGS in the use of these data or related materials.

  4. How can I download or order the data?

  5. What hardware or software do I need in order to use the data set?

    The data are available in ArcView format. The user must have ArcView 3.0 or greater to read and process the data file. In lieu of ArcView, the user may utilize another GIS application package capable of importing the data

Who wrote the metadata?

Last modified: 22-Jan-2004

Metadata author:
U.S. Geological Survey
c/o Lawrence J. Poppe
U.S. Geological Survey
Woods Hole, Massachusetts 02543-1598

(508) 548-8700 x2314 (voice)
(508) 457-2310 (FAX)

Generated by mp version 2.7.3 on Thu Jan 22 07:51:41 2004