摘要：The widespread, uniform till sheets of the southern margin of the Laurentide ice sheet were deposited by fast-moving, wet-bedded ice over relatively short periods of time. Characteristics of these till sheets are entirely consistent with deposition from deforming subglacial sediment layers; it is difficult (although not impossible) to explain their origin through debris transport in basal ice. Careful estimation of debris budgets and studies of sorted sediments contained in the till sheets may clarify their origin further.
