Pine Island Glacier, West Antarctica, is the largest Antarctic contributor to global sea-level rise and is vulnerable to rapid retreat, yet our knowledge of its deglacial history since the
Last Glacial Maximum is based largely on marine sediments that record retreat to ~120 km downstream of the modern grounding line by the early Holocene. We show, with a suite of 10Be exposure ages from onshore glacial deposits directly adjacent to Pine Island Glacier, that this major glacier thinned rapidly in the early- to mid-Holocene. Our results indicate that Pine Island Glacier was at least 690 m thicker than present prior to ~8 ka. We infer that the rapid thinning detected at the site furthest downstream records the arrival and stabilization of the retreating grounding line at that site by 8-6 ka. By combining our exposure ages and the marine record, we
extend knowledge of Pine Island Glacier retreat both spatially and temporally: to 50 km from the modern grounding line and to the mid-Holocene, providing a dataset that is important for future numerical ice sheet model validation.