This dataset contains interpreted polygons describing different sediment texture distribution of the Long Island Sound mapping project Phase II area. This dataset is the result of manual interpretation based on surface grab grain size analysis combined with detailed bathymetry and backscatter data.

Time period of content: 2017-08-01 to 2022-10-13

Data Quality Considerations: Outline of polygons is based on manual interpretation using grain size data from sediment grab analysis and mostly following backscatter boundaries.

Attribute accuracy: We tried to be as accurate as possible. There were smaller areas with different backscatter signal, for which we did not had grab samples for ground verification. Changes in the backscatter values do not always correspond to the observed grain size results. In these cases, we used grain size results from grabs as the main guidance.

Completeness: The dataset is complete.

Positional accuracy: Polygon outlines are based on backscatter data that have 1 m pixel resolution, but interpretation could be several pixels (~ +/-10 m in each direction) of, since the exact boundary is not always clear. Small pockets of different environments might not have been distinguished.

Attributes:

texture: text field that describes the sediment texture class based on Schlee with additional classes added to distinguish coarser bottom types not included in the original Schlee classification:(outcrops with boulders and sand, boulder, boulder with gravel and sand, boulder with sand, gravel, gravelly sediment, sand, sand/silt/clay, silty sand, sandy silt, silty clay, no data)

Area_km2: area of a polygon in square kilometer