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 10Be-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