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

Utilizing Red Relief Imagery in Geologic Mapping

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

Authors

Abstract

Lidar imagery is a valuable resource used to identify geologic contacts. Often, a simple grayscale hillshade or multidirectional hill shade is sufficient for identifying contacts. However, in areas with subtle features or steep slopes, different visualization techniques are required to resolve subtle topographic breaks associated with geologic contacts. A red relief image combines slope, positive openness raster function, and layer blending to enhance terrain visualization and show finer detail in raster elevation models. The resulting imagery provides a robust base for mapping geologic contacts in bedrock and surficial mapping efforts. Here, we present methodology applied by the PaGS to generate a red relief image map and present an example case study where red relief imagery is used in identifying geologic contacts.

A DEM is processed using the Slope tool to identify the steepness of the raster before positive and negative openness are calculated using the Relief Visualization Toolbox. The slope is symbolized using a red gradient, while the positive openness is symbolized with a blue to yellow gradient. The negative openness is symbolized with the inverse of the positive openess. The three rasters are then overlaid, and the layer blend ‘multiply’ is used. The resulting image reveals a ground surface with greater topographic detail.

The Pennsylvania Geological Survey has engaged with preliminary geologic mapping efforts in northern Clearfield County in north central, Pennsylvania. In this region, the regional Mississippian – Pennsylvanian Unconformity results in the Pennsylvanian Pottsville Formation resting directly on the Mississippian Burgoon Formation. Typically, this contact is marked by a topographic bench that corresponds to an upper shaly portion of the Burgoon Formation. However, erosion on the unconformity surface is variably, and locally, the erosion removes the upper shale unit resulting in the basal sandstones of the Pottsville Formation resting directly on the sandstone of the Burgoon Formation. In the absence of the topographic bench, it is difficult to trace this contact with traditional hillshade imagery.

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

doi: 10.1130/abs/2026NE-411384

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