Bedrock Geologic Map of the Old Lyme Quadrangle, New London and Middlesex Counties, Connecticut

Metadata also available as - [Outline] - [XML]

Frequently anticipated questions:

What does this data set describe?

Title:

Bedrock Geologic Map of the Old Lyme Quadrangle, New London and Middlesex Counties, Connecticut

Abstract:

The bedrock geology of the Old Lyme quadrangle, New London and Middlesex Counties, Connecticut is described in this report. The database includes contacts of bedrock geologic units, faults, outcrops, and structural geologic information.

Supplemental_Information:

Data were originally collected in UTM coordinates, zone 18, NAD 1927, and reprojected to polyconic projection, NAD 1927, in meters. The database is accompanied by two large format color maps, an explanatory pamphlet, and a readme.txt file.

  1. How should this data set be cited?

Walsh, G.J., Scott, R.B., Aleinikoff, J.N., and Armstrong, T.R., 2009, Bedrock Geologic Map of the Old Lyme Quadrangle, New London and Middlesex Counties, Connecticut: U.S. Geological Survey Scientific Investigations Map 3052, U.S. Geological Survey, Reston, Virginia.

Online Links:

  1. What geographic area does the data set cover?

West_Bounding_Coordinate: -72.3750

East_Bounding_Coordinate: -72.2500

North_Bounding_Coordinate: 41.3750

South_Bounding_Coordinate: 41.2500

  1. What does it look like?
  2. Does the data set describe conditions during a particular time period?

Beginning_Date: 2001

Ending_Date: 2009

Currentness_Reference: publication date

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

Geospatial_Data_Presentation_Form: Map

  1. 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):

      • GT-polygon composed of chains (186)
    1. 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 .0001. Longitudes are given to the nearest .0001. 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.

  1. How does the data set describe geographic features?

Entity_and_Attribute_Overview:

The geologic data layers in the GIS database of this report include, 1) CONTX - Polygon data layer of bedrock geologic map units, including a lithology attribute table, 2) FAULTS - Line data layer of geologic faults, 3) OUTCROP - Unattributed polygon data layer of bedrock outcrops, and 4) STRUX - Point data layer of ductile and brittle structural geology.

Entity_and_Attribute_Detail_Citation: <https://pubs.usgs.gov/sim/3052/Downloads/readme.txt>

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

U.S. Geological Survey
c/o Gregory J. Walsh
geologist
P.O. Box 628
Montpelier, Vermont 05602
USA

802-828-4528 (voice)
802-828-4465 (FAX)
gwalsh@usgs.gov

Why was the data set created?

The map was published as part of a study of fractured bedrock aquifers. The digital data are intended for use by all government, academic, commercial, or other agencies in need of digital geologic map information.

How was the data set created?

  1. From what previous works were the data drawn?
  2. How were the data generated, processed, and modified?

Date: 2009 (process 1 of 1)

Geology mapped at a scale of 1:24,000. Location information was provided by general purpose hand-held GPS receivers or Rockwell PLGR+96 GPS receivers using the Federal precise positioning service. The line and polygon data were compiled on a Mylar greenline and scanned at 400 dpi. The raster files (TIF) were converted to vector files (DXF) using raster-to-vector conversion software. The vector files were imported to Arc/Info version 8.3. Point data were collected with GPS and hand-held 3COM Palm Pilot III PDA computers. Data from the PDAs and GPS receivers were combined in ArcView version 3.3, converted into shapefiles, and then imported into Arc/Info. Database files were edited as overages in Arc/Info and later converted to shapefiles.

Person who carried out this activity:

Gregory J. Walsh
U.S. Geological Survey
geologist
P.O. Box 628
Montpelier, Vermont 05602
USA

802-828-4528 (voice)
802-828-4465 (FAX)
gwalsh@usgs.gov

Hours_of_Service: 0900 to 1700 eastern standard time

Data sources produced in this process:

  1. 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?

All attributes digitized during the creation process were verified by displaying the lines and points in the database with respect to the USGS 7.5-minute topographic map, but no formal tests were performed.

  1. How accurate are the geographic locations?

The data were created on a USGS 7.5 minute topographic map at 1:24000 scale. Therefore, the horizontal accuracy is assumed to be within National Map Accuracy Standards, with a horizontal accuracy of 45.6 feet at the 95% confidence level. Locational information in the field was provided by general purpose hand-held GPS receivers using the code correlation method Rockwell PLGR+96 GPS receivers using the Federal precise positioning service. GPS positions were adjusted to match the existing topographic base. Raw GPS data are located in the STRUX point coverage.

  1. How accurate are the heights or depths?

The data were delineated on a USGS 7.5 minute topographic map at 1:24000 scale. Therefore, the vertical accuracy is assumed to be within National Map Accuracy Standards, with a vertical accuracy of 11.9 feet at the 95% confidence level.

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

The geologic contacts were delineated on a USGS 7.5-minute topographic map based on observations at the outcrops shown in the database. Not all outcrops within the area were identified or visited during mapping. The geologic contacts might change if additional outcrops are discovered or exposed as the natural land changes or as the result of development. The features in the database are not based on legal parcels or definitions.

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

These data are believed to be logically consistent, although no tests were performed. Line geometry is topologically clean.

How can someone get a copy of the data set?

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

Access_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.

Use_Constraints: none

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

U.S. Geological Survey - Information Services
Box 25286, Denver Federal Center
Denver, Colorado 80225
USA

1-888-ASK-USGS (voice)
ask@usgs.gov

Hours_of_Service: 0900 to 1700 mountain standard time

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

USGS Scientific Investigations Map 3052

  1. What legal disclaimers am I supposed to read?

These data were prepared by an agency of the United States Government. Neither the U.S. Government, the Department of the Interior, nor the U.S. Geological Survey, nor any of their employees, contractors, or subcontractors, make any warranty, express or implied, nor assume any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, nor represent that its use would not infringe on privately owned rights. Although these data have been processed successfully on a computer system at the U.S. Geological Survey, no warranty expressed or implied is made regarding the display or utility of the data on any other system, or for general or scientific purposes, nor shall the act of distribution constitute any such warranty. The U.S. Geological Survey shall not be held liable for improper or incorrect use of the data described and/or contained herein. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.

  1. How can I download or order the data?

Data format:

Geologic units and structural features in format Arc/Info export (version 9.x)

Network links:

<https://pubs.usgs.gov/sim/3052/downloads/SIM3052A.zip>

o 

Data format:

Geologic units and structural features in format Shapefile (version 1.0)

Network links:

<https://pubs.usgs.gov/sim/3052/downloads/SIM3052A.zip>

Who wrote the metadata?

Dates:

Last modified: 30-Oct-2009

Metadata author:

U.S. Geological Survey
c/o Gregory J. Walsh
Geologist
P.O. Box 628
Montpelier, Vermont 05602
USA

802-828-4528 (voice)
802-828-4465 (FAX)
gwalsh@usgs.gov

Hours_of_Service: 0900 to 1700 eastern standard time

Metadata standard:

Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)

Generated by mp version 2.9.8 on Thu Nov 05 08:45:40 2009