Figure 4: Climate and modeled glaciation history in west Greenland throughout the last 1 Myr.

(a) The stacked benthic marine δ¹⁸O record²³ is a proxy for global ice volume and is divided into numbered marine isotope stages (MIS). We determine the exposure history by applying a threshold to this global climate record. (b) The diatom productivity curve from Lake El’gygytgyn³⁵, which is a temperature proxy based on limnic Arctic data, indicating very warm conditions during MIS 11. (c) Quantification of the most likely periods of exposure (‘Exp’ and green coloration) and burial by ice cover (‘Bur’ and blue coloration) based on 39 bedrock samples (black lines) from four sites in the Fjord Area of west Greenland^{19,20,24,25,26} (the Sisimiut exposure/burial history covers the sample sites Itilleq and Sukkertoppen). Red lines mark the glaciation history of samples that only have experienced very short durations of burial and therefore have ²⁶Al/¹⁰Be ratios at or above the production ratio of 6.75. The red lines are based on three samples from Sisimiut and seven samples from Uummannaq. It is likely that the ice sheet extended to the shelf edge and deposited glacial debris flows during the five most prolonged ice-covered periods^5,37.