Abstract

We used cosmogenic 26Al and 10Be in stream sediment to measure landscape-scale erosion rates for topographically diverse catchments at seven Sierra Nevada sites. At three sites, erosion rates and hillslope gradients are strongly correlated, increasing with proximity to fault scarps and river canyons, which appear to have accelerated local base-level lowering rates, and thus increased catchment erosion rates by up to 15-fold. At four other sites, far from fault scarps and river canyons, erosion rates are much more uniform and less sensitive to average hillslope gradient. Our measurements show that contrasts in landscape erosion rates cannot be inferred from hillslope gradients alone, because landscapes can evolve toward a state of erosional equilibrium, in which steep and gentle slopes erode at similar rates.

You do not currently have access to this article.