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An emerging paradigm that equates glaciers to ''buzz saws'' of exceptional erosional efficiency has been strengthened by shortterm (Ͻ10 2 yr) sediment yields from southern Alaska. New lowtemperature cooling ages from this area, the glaciated Chugach-St. Elias Mountains, constrain long-term (10 6 yr) exhumation rates. Vertically averaged exhumation rates reach ϳ3 mm/yr, but are an order of magnitude lower than rates based on short-term sediment yields. Whereas these exhumation rates are not exceptional for orogenic belts, denudation patterns are strongly correlated with the distribution of glaciers, and erosion appears to keep pace with convergence and uplift. These findings imply a coupling between glacially dominated erosion and tectonics.

Exhumation of rocks in extensional tectonic settings results from a combination of normal faulting and erosion but the relative contribution of these processes has rarely been quantified. Here we present new low-temperature thermochronological data and the first 10 Be-based catchment-wide erosion rates from the Boz Dağ region in the central Menderes Massif, which has experienced NNE–SSW extension since the Miocene. The slip rate of the shallow-dipping Gediz detachment fault, which defines the northern flank of the Boz Dağ block, is 4.3 (+3.0/−1.2) mm a −1 , as constrained by zircon (U–Th)/He ages of c . 4–2 Ma in the footwall. Apatite and zircon (U–Th)/He and fission-track ages from the northern flank of the Boz Dağ block yield exhumation rates of 0.6–2 km Ma −1 beneath the Gediz detachment, whereas those on the southern flank are only 0.2–0.6 km Ma −1 . Erosion of catchments on the northern and southern flanks proceeds at rates of 80–180 and 330–460 mm ka −1 , respectively. This marked contrast is a combined effect of the topographic asymmetry of the Boz Dağ block and differences in rock erodibility. If these erosion rates persisted in the past, rock exhumation on the northern flank occurred predominantly by tectonic denudation, whereas rocks on the southern flank were mainly exhumed by erosion.

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