Abstract

Erosion, river incision, and uplift rates in the northern and central Apennines, Italy, since 0.9 Ma, are determined from new cosmogenic nuclide data. Beryllium-10 concentrations in modern and middle Pleistocene sediments indicate erosion rates from 0.20 to 0.58 mm/yr. These rates are similar to estimates of sediment yield (0.12–0.44 mm/yr), river incision (0.35 mm/yr), and uplift (0.01–1.0 mm/yr) rates inferred from other methods that integrate landscape process rates since the early Pleistocene. These rates of landscape change are significantly lower than long-term exhumation rates of ∼1.2 mm/yr since ca. 4.5 Ma, inferred from thermochronometry. Collectively, these data suggest that hillslope erosion and river incision rates in the northern and central Apennines have balanced local uplift rates for ∼1 My, but that exhumation rates have slowed significantly since emergence of the mountain chain in the Pliocene. This condition of dynamic equilibrium was potentially achieved within ca. 3 Ma, similar to some model predictions of hillslope and fluvial system adjustment.

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