171-7 Outcrop Affinity: Automated Detection of Accessible Geologic Outcrops Using LiDAR Data Across the Appalachians

Session: Advancing Geologic Analysis with Digital Outcrops and Close-Range Remote Sensing Data

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Abstract:

Locating geologic outcrops is fundamental to earth sciences research, yet no comprehensive online geospatial databases currently exist that document precise outcrop locations alongside formation names, and geologic ages. Many accessible outcrops remain unrecorded due to remote locations and inadequate field surveys. Recognizing this need, we developed Outcrop Affinity, a novel Python-based algorithm implemented in ArcGIS that systematically identifies exposed geologic formations using publicly available LiDAR data from the USGS National Map Viewer. This slope-based tool detects outcrops by identifying elevation changes exceeding calibrated thresholds, then extracts, filters, and labels outcrops with roadside accessibility. Identified outcrops are paired with Google Street View imagery for visual validation. We optimized detection thresholds for each state through iterative testing to maximize outcrop yield while minimizing false positives (e.g., vegetated slopes, retaining walls). To date, Outcrop Affinity has successfully extracted over 3.6 million potential outcrops across 13 Appalachian Mountain states from Maine to Alabama, with nearly 500,000 exhibiting roadside accessibility. The resulting geospatial database represents a powerful tool for geologists seeking to locate and study outcrops across the eastern United States. Geographic expansion to additional states is ongoing.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-8538

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