Kettle Holes

As the last glacier melted away, sometimes blocks of ice were stranded and became buried as meltwater covered them with outwash sand and gravel. Later, as the ice block melted, the overlying sediment collapsed and left a depression in the ground surface. Some of these kettle holes have ponds of lakes in them kettle lakes). They usually have steep side slopes, and over time accumulate sediment in the bottom. Lakes may eventually fill in with vegetation and create bogs or swamps (see also Gage Street Swamp leaflet).

Kettle holes may be as small as a car, or as big as a house or city block. It may take the ice block thousands of years to melt away. In some cases we think they lasted through a later ice readvance, before finally melting away. Local examples of kettle lakes include Sunfish Lake, Spongy Lake, Pinehurst Lake, and Puslinch Lake. Kettle holes often occur near kames. Several dry kettle holes can be seen southwest of Cambridge.

Paul F. Karrow