Lauren Miller Simkins , Sarah L Greenwood, Monica C.W. Winsborrow, Lilja R. Bjarnadóttir, Allison P. Lepp

Meltwater drainage beneath ice sheets is a fundamental consideration for understanding ice-bed conditions and bed-modulated ice flow, with potential impacts on terminus behavior and ice-shelf mass balance. While contemporary observations reveal the presence of basal water movement in the subglacial environment and inferred styles of drainage, the geological record, including sediments and landforms, on land and the seafloor of former or formerly expanded ice sheets aid in understanding the spatiotemporal evolution of distributed and channelized drainage systems and their impact on ice-sheet behavior. We highlight the past decade of advances in geological studies that focus on providing process-based information on subglacial hydrology of ice sheets, how these studies inform theory, numerical models, and contemporary observations, and address the needs for future research.