Figure 2: Simple exposure ¹⁰ Be ages and long-term denudation rates as a function of altitude.

(a) Simple exposure ¹⁰Be ages tend to increase with elevation. Above a certain threshold (dashed line), all bedrock samples contain a cosmogenic signal inherited from periods before the most recent glaciation. The grey zone marks the limit used to constrain the timing of the Holocene deglaciation (10–16 kyr) for all sites (see ‘Methods’ section). ¹⁰Be ages are calculated using Cronus Version 2.3 (ref. 45) and the Lal (1991)/Stone (2000) scaling scheme^40,41. (b) Total denudation rates over the last 1 Myr based on application of the MCMC approach to samples with a simple exposure ¹⁰Be age above 20 kyr and a ²⁶Al/¹⁰Be ratio below 7.5. All three sites in west Greenland show a clear trend of decreasing denudation rate with increasing elevation. Diamonds represent samples from the same previous studies, but with information from ¹⁰Be only (that is, no ²⁶Al data were available). The rates of denudation associated with these samples have larger uncertainties. Error bars are defined as the first and third quartiles of the 200,000 iterations per sample.