| Summary: | The million-year behavior of ice sheets is poorly understood because younger glaciations remove the terrestrial record of older advances. However, material shed from continents is preserved as marine sediment that can be analyzed to infer glacial process and history. Here, we use measurements of in situ produced cosmogenic 10Be and 26Al in marine sediment cores to understand the long-term behavior of the eastern Greenland Ice Sheet. We find a progressive, order-of-magnitude decline in 10Be over the past 7.5 Myr, consistent with deep, ongoing erosion by ice of the pre-icehouse Greenlandic landscape. 26Al/10Be indicates that much of East Greenland was covered by ice for most of the Pleistocene. At major climate transitions, isotope concentrations and 26Al/10Be change, consistent with ice sheet expansion into previously ice-free terrain. The detrital cosmogenic history reflects major events recorded in the marine benthic δ18O record, confirming that the Greenland Ice Sheet consistently responded to global climate forcing.
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