NPS Photo Kettle ponds are scattered across the outer Cape Cod landscape, an area consisting of glacial outwash plains that formed during the retreat of the Laurentide ice sheet some 18,000 years ago. Depressions in the outwash plain are called kettle holes. They mark the sites of ice blocks that were left behind by the retreating glacier and then buried by outwash sand and gravel deposits. Slow melting of the larger ice blocks left depressions that were deep enough to intersect with the water table. Rising sea levels pushed the outer Cape Cod freshwater lens upward, flooding the kettle holes to form lakes and ponds. These kettle hole lakes and ponds have little to no surface-water inflows or outflows, and receive all of their hydrologic inputs from groundwater and precipitation.
Kettle ponds at Cape Cod National Seashore are, in general, characterized by naturally low concentrations of nutrients, high water clarity, low pH, and low buffering capacity. Within the Cape Cod National Seashore there are 20 named kettle ponds. These ponds have been designated as ecological, recreational, and aesthetic treasures by the Massachusetts Natural Heritage Program for their biodiversity and rare species.
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Last updated: January 31, 2018