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| Value | Definition |
|---|---|
| 1 | Physiographic zones that were defined on the basis of the highest resolution bathymetry (10m) and backscatter (1m), bottom photos, sediment samples, and seismic interpretations were given the highest data interpretation confidence value of 1. |
| 2 | Physiographic zones that were defined on the basis of the highest resolution bathymetry (10m) and/or lidar bathymetry, possibly bottom photos, possibly sediment samples, but no acoustic backscatter or seismic interpretations were given the data interpretation confidence value of 2. |
| Value | Definition |
|---|---|
| Rocky Zone | Rocky zones are rugged areas of high bathymetric relief, characterized by fields of mounded boulders and cobble near the terminal moraines, to relatively flat, gravel-covered, and isolated till highs. Although boulders and coarse-grained sediment are found within most physiographic zones defined here, they dominate the sea floor in rocky zones. |
| Shelf Valleys | Shelf valleys are elongate depressions that extend offshore, often perpendicular to the trend of the coastline, and slope gently seaward. |
| Nearshore Ramp | Nearshore ramps are areas of gently sloping sea floor with generally shore-parallel bathymetric contours. This zone is covered by primarily sandy sediment, though patches of cobbles and boulders crop out on the sea floor in places. Nearshore ramps are typically adjacent to arcuate shoreline areas and grade into deeper-water. |
| Ebb Tidal Delta | Ebb-tidal deltas are lobate sandy shoals found on the side of inlets that form through the interaction of waves and ebbing tidal currents. Ebb-tidal delta zones in the study area are located near Muskeget Channel |
| Hard-Bottom Plains | Hard-bottom plains are mostly low-relief but rough zones of sea floor composed primarily of coarse sands and gravels that are situated adjacent and between the shoal/sand wave zones in the sounds. |
| Coastal Embayment | Coastal embayments include small bays and harbors in the vicinity of Nantucket. |
| Shell Zones | Shell zones are areas that are nearly completely covered by carbonate shells. Portions of sea floor north of Nantucket Sound were mapped where high densities of slipper shells (Crepidula fornicata) cover the sea floor. Despite high acoustic backscatter in sidescan-sonar data, sediment samples recovered primarily muddy sediments beneath the shells. |
| Shoal - Sand Waves | Shoal/sand wave areas are sea-floor zones dominated by linear to sinuous, high relief bedforms primarily composed of sandy sediments that have been reworked from adjacent glacial deposits by energetic waves and tidal currents. The largest shoal extends between Aquinnah and Nomans. |
These sea floor physiographic zones were created from geophysical and sample data collected from south of Martha's Vineyard and north of Nantucket, and are used to characterize the sea floor in the area. Physiographic zone maps 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: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: | shapefile (version ArcGIS v. 10.5.1 shapefile) Size: 0.269 |
|---|---|
| Network links: |
https://www.sciencebase.gov/catalog/item/5bfd6055e4b0815414ca39d9 https://www.sciencebase.gov/catalog/file/get/5bfd6055e4b0815414ca39d9 https://doi.org/10.5066/P9E9EFNE |
| Data format: | ArcGIS v. 10.5.1 shapefile provided through a WMS (web mapping service). in format WMS |
|---|---|
| Network links: |
https://www.sciencebase.gov/catalogMaps/mapping/ows/5aff06aae4b0da30c1bfcde2?service=wms&request=getcapabilities&version=1.3.0 https://www.sciencebase.gov/catalog/item/5aff06aae4b0da30c1bfcde2 https://doi.org/10.5066/P9E9EFNE |
| Data format: | ArcGIS v. 10.5.1 shapefile provided through a WFS (web feature service). in format WFS |
|---|---|
| Network links: |
https://www.sciencebase.gov/catalogMaps/mapping/ows/5aff06aae4b0da30c1bfcde2?service=wfs&request=getcapabilities&version=1.0.0 https://www.sciencebase.gov/catalog/item/5aff06aae4b0da30c1bfcde2 https://doi.org/10.5066/P9E9EFNE |
These data are available in Environmental Systems Research Institute (Esri) shapefile format. The user must have software capable of importing and processing this data type.
