Massachusetts Soil Evaluator Practice Test

Glacial till is sediment deposited directly by ice, without being sorted by meltwater. The term lodgement till refers to the material that collects at the base of the glacier as debris is pressed and melts out from the moving ice and becomes lodged against the bed. This produces a dense, poorly sorted mix of clay through boulders that forms beneath the glacier as it advances. Outwash is the sorted sediment laid down by meltwater after it leaves the glacier, moraine describes the landforms built from till at the edges or terminus, and basal till is a related subglacial term, but lodgement till specifically captures the deposition that occurs beneath the ice itself.