Data Catalog

Document Type

Data Set

Publication Date



WGOM, Continental Shelf, Surficial Geology Maps, Sediment, Geoforms


Center for Coastal and Ocean Mapping, Data Catalog


Geology | Geomorphology | Oceanography | Sedimentology

Description or Abstract

The “New Hampshire Continental Shelf Geospatial Database: Surficial Geology Maps and Sediment Grain Size Data” consists of high-resolution surficial geology maps of the continental shelf off New Hampshire to Jeffreys Ledge in the Western Guff of Maine (WGOM) and supporting sediment grain size information. The surficial geology maps cover ~3,250 km2 (Figure 1). The maps depict three different classifications based on the Coastal and Marine Ecological Classification Standards (CMECS; FGDC, 2012): Geoforms (major morphologic or physiographic features; Figure 2; Table 1), Geologic Substrate Subclass (Figure 3; Table 2), and Geologic Substrate Group (Figure 4; Table 2). The maps are presented in a fully downloadable ArcMap 10.8.1 project with the supporting geodatabase.

The surficial geology maps were developed from high-resolution multibeam echosounder (MBES) bathymetry and backscatter surveys along with ground truth (Figure 5) consisting of seismic reflection profiles, bottom sediment grain size data, vibracores, and seafloor videography (originally published in Ward et al., 2021i). Differences in the observed bathymetric derivatives such as hillshade, roughness, BPI, and backscatter served as traceable outlines of different seafloor environments. Grain size data from sediment samples collected on the NH shelf were used to verify and improve interpretations. Polygons were manually drawn using the Create Polygon Feature tool within an editing session, resulting in ~4,900 individual polygon features.


Grant/Award Number and Agency

National Oceanic and Atmospheric Administration Joint Hydrographic Center Award Number NA15NOS4000200 and the Bureau of Ocean Energy Management Award Number M14AC00010.


Public (open access)