| Summary: | During the early Devensian, ice formed only in Cumbria. By 22,000 BP the northwest of England was covered by ice emanating from Scotland and the Lake District. The ice sheet was warmbased, with subglacial water movement within tunnel valleys. As the climate warmed the ice receded northwards, leaving moraines and stagnant ice features. During the later stages of recession, subglacial water began to move through the thick till bed, and deformation of this sediment into drumlins occurred. This process was aided by the marine inundation of the Irish Sea basin, forming a tidewater glacier margin, and causing rapid drawdown and calving of icebergs. After the main ice sheet had disintegrated, a cold snap led to the reformation of ice in the Pennines and Lake District.
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