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171-3 From Outcrop to Point Cloud: Using Three-Dimensional Techniques to Study Fluvial Dynamics During the Paleocene-Eocene in Wyoming

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

Presenting Author:

Filip Novak

Authors:

Novak, Filip¹, Howes, Bolton J.², Foreman, Brady Z.³, Mehra, Akshay⁴

(1) Department of Earth and Space Sciences, University of Washington, Seattle, Washington, USA, (2) Department of Earth and Space Sciences, University of Washington, Seattle, Washington, USA; Department of Earth and Environmental Science, Wheaton College, Wheaton, Illinois, USA, (3) Geology Department, Western Washington University, Bellingham, Washington, USA, (4) Department of Earth and Space Sciences, University of Washington, Seattle, Washington, USA,

Abstract:

Three-dimensional (3D) features of sedimentary outcrops can provide insights into the environments, hydrology, and tectonic settings in which the rocks formed. In river systems, one such feature are cross-sets, which preserve fluvial responses to environmental shifts. Measurements of the thicknesses and variation among these cross-sets can reveal changes in river behavior, such as flash flooding and channel migration. Although previous studies have collected cross-set measurements in the field, 3D modeling presents opportunities for the development of accessible, higher accuracy workflows to extract and verify measurements from digital reconstructions following fieldwork. Here, we introduce a technique to assess the shape, thickness, and variability of cross-sets (a method we can also apply to other structures in the sedimentary rock record) while correcting for modern weathering-related distortion. Our method leverages structure from motion (SfM) photogrammetry, which enables us to construct millimeter-scale 3D models of outcrops. We use these models to extract detailed measurements from outcrops that are otherwise challenging to quantify in the field and revisit them virtually for further analysis. Due to the digital nature of our approach, we are able to adjust the resolution and type of measurement that we extract from each cross-set long after initial data collection. We present a case study from the Bighorn Basin of Wyoming, where we apply our technique to investigate how fluvial systems responded to increased temperatures and precipitation during the Paleocene-Eocene Thermal Maximum (PETM). We explore various hypotheses regarding the extent of change in river behavior before, during, and after the PETM, and provide additional insights into how the fluvial rock record preserves unsteady versus steady flow regimes. Our results demonstrate that 3D modeling and the data we extract using accessible workflows lead to analyses that further our understanding of the rock record at an enhanced level of precision and accuracy. Together, these analyses and workflows translate to robust and meaningful paleohydrologic and paleoenvironmental reconstructions, expanding and refining the interpretation of meter-scale outcrops on Earth and beyond.

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

doi: 10.1130/abs/2025AM-7047

From Outcrop to Point Cloud: Using Three-Dimensional Techniques to Study Fluvial Dynamics During the Paleocene-Eocene in Wyoming

Description

Session Format: Oral

Presentation Date: 10/21/2025

Presentation Start Time: 08:35 AM

Presentation Room: HBGCC, 301C

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