Anthropogenic wastes, toxic chemicals, and changes in land-use patterns resulting from residential, commercial, and recreational development have stressed the environment of the Sound, causing degradation and potential loss of benthic habitats (Koppelman and others, 1976; Long Island Sound Study, 1994). Detailed maps of the sea floor are needed to help evaluate the extent of adverse impacts and to help manage resources wisely in the future. Therefore, in a continuing effort to better understand Long Island Sound, we have constructed and interpreted sidescan sonar mosaics (complete-coverage acoustic images of the sea floor) within specific areas of special interest (Poppe and Polloni, 1998; fig. 1). The mosaic presented herein covers a 190.3 km square area of the sea floor in west-central Long Island Sound off Bridgeport, Connecticut.
The mosaics and their interpretations serve many purposes, including: (1) defining the geological variability of the sea floor, which is one of the primary controls of benthic habitat diversity; (2) improving our understanding of the processes that control the distribution and transport of bottom sediments and the distribution of benthic habitats and associated infaunal community structures; and (3) providing a detailed framework for future research, monitoring, and management activities. The sidescan sonar mosaics also serve as base maps for subsequent sedimentological, geochemical, and biological observations, because precise information on environmental setting is important for selection of sampling sites and for accurate interpretation of point measurements.
Beaulieu, Elizabeth, 2005, Sedenviron: Interpretation of the Distribution of Sedimentary Environments of the Sidescan sonar Mosaic of NOAA survey H11045 off Bridgeport, CT: Open File Report 2005-1162, U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole Science Center, Woods Hole, MA.This is part of the following larger work.Online Links:
Beaulieu, E., Poppe, L.J., Paskevich, V.F., Doran, E.F., Chauveau, B.E., Crocker, J.M., Beaver, A.L, and Schattgen, P.T., 2005, Sidescan Sonar Imagery and Surficial Geologic Interpretation of the Sea Floor off Bridgeport, Connecticut: Open-File Report 2005-1162, U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole Science Center, Woods Hole, MA.Online Links:
This is a Vector data set. It contains the following vector data types (SDTS terminology):
Horizontal positions are specified in geographic coordinates, that is, latitude and longitude. Latitudes are given to the nearest 0.000000. Longitudes are given to the nearest 0.000000. Latitude and longitude values are specified in Decimal degrees.
The horizontal datum used is D_WGS_1984.
The ellipsoid used is WGS_1984.
The semi-major axis of the ellipsoid used is 6378137.000000.
The flattening of the ellipsoid used is 1/298.257224.
Sequential unique whole numbers that are automatically generated.
Coordinates defining the features.
Range of values | |
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Minimum: | 0 |
Maximum: | 0 |
Value | Definition |
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Erosion or Nondeposition | High energy environment not permitting the accumulation of recent sediments |
Coarse Bedload Transport | High energy envronment characterized by sand ribbons and sand waves |
Sorting or Reworking | Moderate energy environment that separates fine-grained sediments from coarser ones, by winnowing |
Fine Grained Deposition | Lower energy environemtn alling the accumulation of modern sediments |
Please credit Elizabeth Beaulieu, U.S. Geological Survey, for completing the interpretation.
(508) 548-8700 x2314 (voice)
(508) 457-2310 (FAX)
lpoppe@usgs.gov
This GIS overlay is a component of the Bridgeport Survey, Long Island Sound, GIS database and shows the distribution of sedimentary environments within the study area.
Person who carried out this activity:
(508) 548-8700 x2277 (voice)
(508) 457-2310 (FAX)
ebeaulieu@usgs.gov
Data sources produced in this process:
(ediror), V.F. Paskevich , and Poppe, L.J., 2000, Georeferenced Mapping and Bottom Photography in Long Island Sound.Online Links:
- <http://pubs.usgs.gov/openfile> /of00-304/
Poppe, L.J., Paskevich, V.F., Moser, M.S., DiGiacomo-Cohdn, M.L., and Christman, E.B., 2004, Sidescan Sonar Imagery and Surficial Geologic Intrpretation of the Sea Floor off Branford, Connecticut: Open-File Reporter 2004-1003, U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole Science Center, Woods Hole, MA.Online Links:
McMullen, K.Y., Poppe, L.J., Paskevich, V.F., Doran, E.F., Moser, M.S., Christman, E.B., and Beaver, A.L., 2005, Surficial Geologic Interpretation and Sidescan Sonar Imagery of the Sea Floor off West-Central Long Island Sound: Open-File Report 2005-1018, U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole Science Center, Woods Hole, MA.
Interpretations are based on tonal changes on a sidescan sonar mosaic that was navigated with differential GPS; positional accuracy to less than 10 m.
Interpretations of the sedimentary environments across the sidescan sonar mosaic were completed using tonal changes and all available textural data.
All polygons were constructed in a consistent manner. No additional checks for topological consistency were performed on this data.
Are there legal restrictions on access or use of the data?
- Access_Constraints: None
- Use_Constraints:
- Public domain data are freely redistributable with proper metadata and source attribution. Please recognize the U.S. Geological Survey (USGS) as the originator of this dataset.
(508) 548-8700 x2314 (voice)
(508) 457-2310 (FAX)
lpoppe@usgs.gov
Downloadable Data
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.
Data format: | Five files: sedenviron.shp, sedenviron.shx, sedenviron.dbf, sedenviron.avl, sedenviron,prj in format ArcView shapefile (version 3.3) ESRI golygon shapefile Size: 41.5 KB |
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Media you can order: | DVD (Density 650 Mbytes) (format ISO9660) |
The data are available in the ESRI shapefile format. The user must have Environmental Systems Research Institute's (ESRI) ArcView 3.0 or greater or ArcGIS software to read and process the data file. In lieu of Arcview, the user may utilize another GIS application package capable of importing the data. A free GIS data viewer, ArcExplorer, is available from the ESRI website at www.esri.com/software/arcexplorer/download4.html
(508) 548-8700 x2314 (voice)
(508) 457-2310 (FAX)
lpoppe@usgs.gov