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| Value | Definition |
|---|---|
| S99 | The nearly total texture (~99 %) Sand (S) is given the upper case letter and a 99 to indicate that the sediment texture is nearly 99 percent sand and indicative of sand ridge material |
| M | The end-member texture (> 90%) Mud (M) is the primary texture. |
| Ms | The dominant texture (> 50%) Mud (M) is given the upper case letter and the subordinate texture (< 50%) sand (s) is given a lower case letter. |
| S | The end-member texture (> 92%) Sand (S) is the primary texture. |
| Sg | The dominant texture (> 50%) Sand (S) is given the upper case letter and the subordinate texture (< 50%) gravel (g) is given a lower case letter. |
| Sm | The dominant texture (> 50%) Sand (S) is given the upper case letter and the subordinate texture (< 50%) mud (m) is given a lower case letter. |
| Gs | The dominant texture (> 50%) Gravel (G) is given the upper case letter and the subordinate texture (< 50%) sand (s) is given a lower case letter. |
| Value | Definition |
|---|---|
| 3 | Sediment texture regions that were defined based on sidescan sonar-mosaics, bathymetric derivatives, and bottom photos and sediment samples, were given the highest data interpretation confidence value of 3 (highest confidence). |
| 2 | Areas where sediment texture was defined based on sidescan sonar-mosaics and bathymetric derivatives, but no bottom photos or sediment samples were available with in the polygon, were given a confidence value of 2 (moderate confidence). |
| 1 | Sediment texture regions that were defined based on bathymetric derivatives, but no sidescan-sonar data (with or without sample information), were given the lowest data interpretation confidence value of 1 (lowest confidence). |
| Range of values | |
|---|---|
| Minimum: | 0 |
| Maximum: | 29 |
| Units: | count |
| Resolution: | 1.0 |
| Range of values | |
|---|---|
| Minimum: | 0 |
| Maximum: | 76.39 |
| Units: | percent |
| Resolution: | 0.1 |
| Range of values | |
|---|---|
| Minimum: | 8.85 |
| Maximum: | 99.96 |
| Units: | percent |
| Resolution: | 0.01 |
| Range of values | |
|---|---|
| Minimum: | 0.04 |
| Maximum: | 91.06 |
| Units: | percent |
| Resolution: | 0.1 |
| Range of values | |
|---|---|
| Minimum: | 0.18 |
| Maximum: | 92.91 |
| Units: | percent |
| Resolution: | 0.1 |
| Value | Definition |
|---|---|
| trace | The weight percent of the coarse fraction (sand + gravel) that is carbonate is less than 2 percent |
| present | The weight percent of the coarse fraction (sand + gravel) that is carbonate is more than 2 percent but less than 10 percent |
| abundant | The weight percent of the coarse fraction (sand + gravel) that is carbonate is more than 10 percent but less than 50 percent |
| dominant | The weight percent of the coarse fraction (sand + gravel) that is carbonate is more than 50 percent |
| Value | Definition |
|---|---|
| sand ridge or bedform | the seafloor geomorphology (as characterized from hillshaded relief, slope, and rugosity imagery) can be described as a series or part of a bedform or sand ridge. Mean slope values for sand ridges can vay greatly, but are typically high, especially along slipfaces and flanks. The mean slope of all polygons classified as 'sand ridge or bedform' is 0.6 degrees. |
| pits | the seafloor geomorphology (as characterized from hillshaded relief, slope, rugosity, and backscatter imagery) can be characterized as scour pits filled with mud. The mean slope of all polygons classified as 'pits' is 0.3 degrees. |
| gently-sloping shelf | the seafloor geomorphology (as characterized from hillshaded relief, slope, and rugosity imagery) can be described as a seaward-sloping relatively-smooth surface with a low slope (on average less than 0.20 degrees for all polygons identified as 'gently-sloping shelf) and not associated with a sand ridge or bedform. Polygons classified as 'gently-sloping shelf' are mostly located in the 2015 survey area where there are fewer sand ridges and thus larger extents of relatively smooth and featureless inner continental shelf. |
| moderately-sloping shelf | the seafloor geomorphology (as characterized from hillshaded relief, slope, and rugosity imagery) can be described as a seaward-sloping relatively-smooth surface with a moderate slope (on average about 0.45 degrees for all polygons identified as 'moderately-sloping shelf') and not associated with a sand ridge or bedform. Polygons classified as 'moderately-sloping shelf' are typically narrow and located mostly in the 2014 survey area between features identified as 'sand ridges or bedform' |
| Range of values | |
|---|---|
| Minimum: | 0.068267 |
| Maximum: | 2.175318 |
| Units: | degrees |
| Resolution: | 0.0001 |
These sea-floor data were created from geophysical and sample data collected along the Delmarva Peninsula from Fenwick Island, Maryland to Fisherman's Island, Virginia. These data are an interpretation of the seafloor sediment type, distribution, and geomorphology, and are classified according to a modified Barnhardt bottom-type classification system in order to capture meaningful changes in seafloor texture along the inner continental shelf of this region. Seafloor interpretations are important data layers for marine resource managers charged with protecting fish habitat, delineating marine boundaries, and assessing environmental change due to natural or human impacts.
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Are there legal restrictions on access or use of the data?Access_Constraints: None
Use_Constraints:Not to be used for navigation. 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. Additionally, there are limitations associated with qualitative sediment mapping interpretations. Because of the scale of the source geophysical data and the spacing of samples, not all changes in sea floor texture are captured. The data were mapped between 1:8,000 and 1:25,000, but the recommended scale for application of these data is 1:25,000.
Neither the U.S. Government, the Department of the Interior, nor the USGS, 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. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the U.S. Geological Survey in the use of these data or related materials. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
| Data format: | This dataset contains the shapefile of qualitatively derived polygons that define sea floor texture and distribution along Fenwick and Assateague Island and parts of Virginia and the associated metadata. in format Shapefile (version ArcGIS 10.2.2) Esri Polygon Shapefile |
|---|---|
| Network links: |
https://www.sciencebase.gov/catalog/file/get/58de56a5e4b02ff32c699fcf https://doi.org/10.5066/F78K779J |
| Data format: | This dataset contains the shapefile of qualitatively derived polygons that define sea floor texture and distribution along Fenwick and Assateague Island and parts of Virginia. in format WMS (version 1.3.0) |
|---|---|
| Network links: |
https://www.sciencebase.gov/catalogMaps/mapping/ows/58de56a5e4b02ff32c699fcf?service=wms&request=getcapabilities&version=1.3.0 https://doi.org/10.5066/F78K779J |
| Data format: | This dataset contains the shapefile of qualitatively derived polygons that define sea floor texture and distribution along Fenwick and Assateague Island and parts of Virginia. in format WFS (version 1.0.0) |
|---|---|
| Network links: |
https://www.sciencebase.gov/catalogMaps/mapping/ows/58de56a5e4b02ff32c699fcf?service=wfs&request=getcapabilities&version=1.0.0 https://doi.org/10.5066/F78K779J |
These data are available in Esri shapefile format. The user must have software capable of importing and processing this data type.
