SPATIALLY AVERAGED LONG-TERM EROSION RATES MEASURED FROM IN SITU-PRODUCED COSMOGENIC NUCLIDES IN ALLUVIAL SEDIMENT

Spatially averaged erosion rates of small catchments can be accurately inferred from the concentrations of cosmogenic nuclides in stream sed iment. Here we test this technique at two catchments by comparing eros ion rates inferred from cosmogenic nuclides with rates of alluvial fan deposition over the past 16,000 years. These two independent estimate s agree within one standard error, demonstrating that cosmogenic nucli de signatures of stream sediment can be used to measure spatially aver aged long-term erosion rates. Using this technique, we show that long- term erosion rates are an exponential function of average hillslope gr adient at these sites.