Sediments off the eastern United States vary markedly in texture - the size, shape, and arrangement of their grains. However, for descriptive purposes, it is typically most useful to classify these sediments according to their grain-size distributions. Starting in 1962, the U.S. Geological Survey (USGS) and the Woods Hole Oceanographic Institution (WHOI) began a joint program to study the marine geology of the continental margin off the Atlantic coast of the United States. As part of this program and numerous subsequent projects, thousands of sediment samples were collected and analyzed for particle size. The sediment map of the Continental Margin Mapping Program (CONMAP) series is a compilation of grain-size data produced in the sedimentation laboratory of the Woods Hole Science Center (WHSC) of the Coastal and Marine Geology Program (CMGP) of the U.S. Geological Survey (USGS) and from both published and unpublished studies. Sediment was classified using the Wentworth (1929) grain-size scale and the Shepard (1954) scheme of sediment classification. Certain grain-size categories are combined because of the paucity of some sediment textures; blank parts of the maps indicate areas where data are insufficient to infer sediment type. Bathymetry is used as a guide in placing some of the contacts between different sediment types. However, because the true boundaries between sediment types are probably highly irregular or gradational, because the extreme textural variability that characterizes some areas does not appear at this scale, and because the accuracy of the navigational systems used during the earlier studies is limited, all contacts should be considered to be inferred. The sediment classification for any given polygon (i.e. area) reflects the dominant surficial sediment type for that polygon. It does not mean that other sediment types are not present within the polygon, only that the dominant sediment type is the one that is most common.
The purpose of the CONMAPSG sediment layer is to show the sediment grain size distributions. The maps depicted in this series are old and do not accurately depict small-scale sediment distributions or sea-floor variability. This data layer is supplied primarily as a gross overview and to show general textural trends.
ground condition
Public domain data from the U.S. Government are freely redistributable with proper metadata and source attribution. Please recognize the U.S. Geological Survey (USGS) as the source of this information.
384 Woods Hole Road
The assigned sediment attributes in this data set are believed to be accurate. The sediment classification for any given polygon (i.e. area) reflects the dominant surficial sediment type for that polygon. It does not mean that other sediment types are not present within the polygon, only that the dominant sediment type is the one that is most common.
These data are believed to be logically consistent, although not tested. Geometry appears to be topologically clean.
This dataset covers the GLORIA project area for the United States East Coast Atlantic Ocean Exclusive Economic Zone (EEZ) area.
The accuracy of this dataset is based on source data that is assumed to have met National Map Accuracy Standards
Map was used as source during process of digitizing sediment polygons.
Map was used as source during process of digitizing sediment polygons.
was used as source during process of digitizing sediment polygons.
Map was used as source during process of digitizing sediment polygons.
Source maps from the Gulf of Maine and Georges Bank and the mid-Atlantic, Cape Cod to Albemarle Sound were digitized in PC Arc Info to create a vector line data set of sediment polygon boundaries, registered to the NOAA medium-resolution shoreline, and processed to create a polygon dataset.
1084 Shennecossett Road
Source maps from the remaining two areas (Carolina Trough, Albemarle Sound to Charleston and South Atlantic and Blake Plateau) were digitized to create a vector line data set of sediment polygon boundaries.
384 Woods Hole Road
The "line" data generated from digitizing the sediment boundaries of the Carolina Trough, Albemarle Sound to Charleston and the South Atlantic and Blake Plateau areas were registered to the NOAA medium-resolution shoreline, combined with the data from the Gulf of Maine and Georges Bank and the mid-Atlantic, Cape Cod to Albemarle Sound, and processed in ArcInfo to create the a polygon dataset of the entire U.S. east coast.
Mill Wharf Plaza, suite 208
Removed the "land" and "no data" polygons and the ArcInfo fields from the shapefile.
384 Woods Hole Road
Merged some polygons that had previously been divided by old Continental Margin Mapping Program boundaries. The split polygons showed unnecessary boundaries. Combining the polygons provides a better representation of the East Coast dataset.
384 Woods Hole Road
Internal feature number.
ESRI
Feature geometry.
ESRI
Area of polygon in native units
Software Computed
Length of polygon perimeter in native units
Software Computed
Assigned code describing sediment.
U.S. Geological Survey
bedrock
U.S. Geological Survey
gravel
U.S. Geological Survey
gravel-sand
U.S. Geological Survey
sand
U.S. Geological Survey
clay-silt/sand
U.S. Geological Survey
sand/silt/clay
U.S. Geological Survey
sand-clay/silt
U.S. Geological Survey
sand-silt/clay
U.S. Geological Survey
clay
U.S. Geological Survey
Assigned code describing sediment
U.S. Geological Survey
bedrock
USGS
gravel
USGS
gravel-sand
USGS
sand
USGS
clay-silt/sand
USGS
sand-clay/silt
USGS
clay
USGS
sand-silt/clay
USGS
sand/silt/clay
USGS
384 Woods Hole Road
Although this derived data set and its lineage dataset have been used by the USGS, 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. Trade, firm, or product names and other references to non-USGS products and services are provided for information only and do not constitute endorsement or warranty, express or implied, by the USGS, USDOI, or U.S. Government, as to their suitability, content, usefulness, functioning, completeness, or accuracy.
ESRI Shapefile
The SHP file contains the geospatial data. The SHX file contains the index of the geospatial data. The DBF file contains the attribute data in dBASE format. The PRJ file contains the coordinate system information (optional). The AVL file contains the legend information (optional). The SBN and SBX files contain the spatial index of the geospatial data (optional). The XML file contains the metadata describing the data set <data set name>.shp.xml. An ASCII version of the metadata file. A browse graphic showing the data layer coverage and extent (optional).
384 Woods Hole Road