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Climate is widely thought to regulate erosion rates, but the relationships among precipitation, temperature, and erosion rate have remained speculative, because long-term erosion rates have been difficult to measure. We used cosmogenic nuclides to measure long-term erosion rates at climatically diverse sites in the Sierra Nevada, California, spanning 20‐180 cm/yr in annual precipitation and 4‐15 8C in mean annual temperature. Average erosion rates vary by only 2.5 fold across these sites and are not correlated with climate, indicating that climate only weakly regulates nonglacial erosion rates in mountainous granitic terrain.

We used cosmogenic 26 Al and 10 Be 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.