A PRELIMINARY SURFICIAL MATERIALS MAP OF RHODE ISLAND

The Preliminary Surficial Materials Map of Rhode Island is a 1:24,000-scale geologic map geodatabase. This compilation map defines the areas of exposed bedrock, glacial till and moraine deposits, glacial stratified deposits, and large areas of artificial fill as stacked polygons arranged in order according to stratigraphic superposition. The intent of this preliminary database is to provide high resolution vector data in Geologic Map Schema (GeMS) format for traditional uses such as ground water modeling and aggregate resource assessments, as well as bedrock surface modeling and 3D applications. The materials map will also function as a starting point for future state-scale and regional-scale Quaternary geologic maps. Map units and concepts are consistent with the Surficial Materials Map of Massachusetts (https://pubs.er.usgs.gov/publication/sim3402) and will edge-match seamlessly with a planned GeMS revision of the Surficial Materials Map of Connecticut.

The map is compiled from more than sixty published sources, however, it is updated and revised to fit a modern lidar base map and includes newly mapped areas of bedrock, glacial stratified deposits, end moraine deposits, and thick till. Although recent fieldwork has been limited, borehole databases and new passive seismic data have been utilized to confirm some interpretations. For this preliminary version of the map, the only postglacial deposits that are included in the geodatabase are large areas of artificial fill as they can potentially impact bedrock surface models. Creation of this database brings the New England Top of Rock effort another step closer to the long-term objective of developing regionwide 3D models depicting the bedrock surface and thickness of surficial deposits.