Rates of erosion over time provide a valuable tool for gauging tectonic and climatic drivers of landscape evolution. Here we measure 10Be archived in quartz sediment from the Fish Creek-Vallecito basin to resolve a time series of catchment-averaged erosion rates and to test the hypothesis that aridity and increased climate variation after approximately 3 Ma led to an increase in erosion rates in this semiarid, ice-free setting. The Fish Creek-Vallecito basin, located east of the Peninsular Ranges in Southern California, is an ideal setting to derive a Plio-Pleistocene paleoerosion rate record. The basin has a rapid sediment accumulation rate, a detailed magnetostratigraphic age record, and its stratigraphy has been exposed through recent, rapid uplift and erosion. A well-deﬁned source region of uniform lithology and low erosion rate provides a high, reproducible 10Be signal. We ﬁnd that paleoerosion rates were remarkably consistent between 1 and 4 Ma, averaging 38 ± 24 m/Myr (2σ). Modern catchment-averaged erosion rates are similar to the paleoerosion rates. The uniformity of erosion over the past 4 Myr indicates that the landscape was not signiﬁcantly aﬀected by late Pliocene global climate change, nor was it aﬀected by a local long-term increase in aridity.
Journal of Geophysical Research: Earth Surface
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Oskin,M.E.,N.E.Longinotti,T. C. Peryam, R. J. Dorsey, C. J. DeBoer,B. A. Housen, and K. D. Blisniuk (2017),Steady10Be-derived paleoerosionrates across the Plio-Pleistoceneclimate transition, Fish Creek-Vallecitobasin, California, J. Geophys.Res. Earth Surf., 122, 1653–1677,doi:10.1002/2016JF004113.
Supporting Information S1
jgrf20742-sup-0002-supplementary.txt (6 kB)
jgrf20742-sup-0003-supplementary.xlsx (21 kB)
jgrf20742-sup-0004-supplementary.txt (1 kB)
Data Set S1
jgrf20742-sup-0005-supplementary.txt (2 kB)
Data Set S2