publication, hillslopes, bedrock, weathering

New study reveals internal structure of hillslopes

March 23, 2021
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Jesse Hahm has published a new study in the Journal of Geophysical Research-Earth Surface that reveals the internal structure of hillslopes in repeating ridge-valley topography.

From the study summary:

The patterns of bedrock weathering concealed beneath the surface have important implications for the water cycle. In many upland landscapes, sequences of ridges and valleys result from river incision into bedrock, which organizes the landscape into hillslopes separated by channels. While surface topography of these landscapes is easily visible, the structure of weathered bedrock beneath the surface and its relationship to overlying topography are unknown. In this study, we observed systematic patterns of weathering and water storage under three hillslopes that make up a repeating ridge‐valley sequence formed in sedimentary bedrock. Across the study area, weathering is thickest under ridges and thins downslope toward adjacent valleys, where fresh bedrock lies almost directly below channels. Interestingly, the depth of extensive weathering and seasonal water storage at the ridges was comparable across all three hillslopes, while open fractures and discoloration persist to a deeper depth under the longer hillslope. These observations provide a basis for scaling point measurements of weathering to the landscape scale, which is a much‐needed tool for models of earth surface processes.

Link to article:

https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2020JF005848