Diana Valenzuela Davila / Earth & Environmental Sciences / Faculty Mentor: Nathan Brown
Ventifacts are rock formations sculpted by wind-driven sand, offering insight into wind erosion processes. Despite their significance in understanding long-term aeolian erosion, few studies have quantified the erosion rates responsible for their formation. Our research aims to estimate these rates using optically stimulated luminescence (OSL) depth profiles at two locations in southern California: Silver Lake and Garnet Hill.
OSL signals in quartz and feldspar bleach deeper into the rock with longer exposure or lower erosion rates, allowing us to detect cm-scale erosion over decades to millennia. By leveraging this method, we address a critical gap in understanding how wind-driven erosion varies across different ventifact surfaces and throughout the recent climate past.
We collected rock samples from 10 ventifact boulders, targeting various facets to analyze erosion rates. In the lab, samples were cored and wafered into ~1.2-mm-thick rock discs using a water-cooled drill press and a diamond wafering saw to estimate the luminescence intensity versus depth into the rock interior. Infrared stimulated luminescence (IRSL) and post-IR-IRSL signals from these wafers were measured with an automated Risø TL/OSL reader. This study examines luminescence depth profiles to infer erosion rate differences across ventifact surfaces, providing insight into surface weathering processes.
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