7 Geologic mapping in the digital age: products, workflows, and methodologies (Posters)

This session will highlight geologic maps and their derivatives, showcasing products that leverage innovative digital methods and workflows, novel application of remote sensing data, and integration of advanced data processing techniques.

Sunday, 22 March 2026
8:00 AM - 12:00 PM
CCC, Ballroom C

Rhode Island Top of Rock: Refining Geospatial Modeling of Bedrock Altitude and Overburden Thickness

Paper number: 7-6
Program: Technical Sessions
Time: 8:00 AM – 8:00 AM

Authors

Abstract

The Rhode Island Top of Rock Project extends from the larger USGS Quaternary Geologic Mapping of the Glaciated Regions Project to examine the spatial distribution of bedrock altitude and overburden thickness across the state of Rhode Island. The project employs geospatial analysis and interpolation techniques guided by the methodologies outlined in the Massachusetts Depth to Bedrock Final Report. Following the conceptual framework developed for statewide subsurface mapping in Massachusetts, inverse distance weighting interpolation was applied. This approach generated a continuous bedrock altitude surface raster from discrete point observations derived from historical well records, seismographic data, and mapped bedrock outcrops. The ⅓ arc-second USGS digital elevation model was used to calculate overburden thickness as the difference between this surface elevation and the modeled bedrock altitude.

The resulting overburden map demonstrates substantial spatial variability in sediment thickness throughout Rhode Island, with strong correspondence to regions with shallow bedrock and thick till in preliminary statewide surficial materials mapping. Ongoing efforts are focused on digitizing additional historical well data to improve interpolation accuracy and refine overburden estimates. A reproducible Python-based workflow package is also in development to streamline the transformation of spatial point data into overburden thickness interpolation maps.

This project demonstrates the applicability of established depth-to-bedrock methodologies to Rhode Island and provides a reproducible framework to support future developments such as groundwater assessment, infrastructure planning, and geologic hazard evaluation.

Geological Society of America Abstracts with Programs. Vol. 58, No. 2

doi: 10.1130/abs/2026NE-411298

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