224-1 Measurements of glacial erosion rates: Pitfalls, uncertainties, and strategies for comparing erosion rates derived from different methods

Session: From the Cosmos and Back: Quantifying Processes and Rates of Landscape Change (Posters)

Presenting Author:

Authors:

Abstract:

Rates of glacial erosion are measured in a variety of ways, including: (i) the flux of sediments in proglacial streams, (ii) the volume of sediments accumulated in proglacial basins, the exhumation of bedrock recorded by (iii) cosmogenic nuclides or (iv) low temperature thermochronometers, and (v) the relief or morphology of glacial landscapes. Comparing erosion rates across methods is difficult because each method fundamentally measures a different indirect phenomenon purported to reflect glacial erosion. This is of particular concern because each method is typically applied to different timescales (ranging from ~10⁰ to 10⁷ years), meaning that the inferred timescale-dependence (Koppes and Montgomery, 2009) or lack thereof (Wilner et al., 2024) of glacial erosion rates may be obscured by biases or limitations inherent to each measurement method. Here, we expand upon and refine existing compilations of glacial erosion rates, and contextualize the information gained from each measurement method to identify likely sources of over- or under-estimates of subglacial bedrock erosion. We categorize erosion rate measurements based on the glacial erosional environment (e.g. Sugden, 1974) to identify confounding variables that may bias the inferred timescale dependence of glacial erosion rates. We suggest strategies for comparing erosion rates derived from different methods that attempts to reconcile the different physical phenomena measured. We conclude that uncertainties are considerable when comparing glacial erosion rates across different methods, motivating future field studies designed to directly compare erosion rates from multiple independent methods.

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

doi: 10.1130/abs/2025AM-7277

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