As the glaciers of the Ice Age receded about 18,000 years ago, huge chunks of ice were left scattered across the landscape. When these ice blocks melted, they left depres-sions in the earth. Then, as the Cape’s water table rose, numerous “kettle ponds” began to appear.
Salt Pond was originally a freshwater kettle, but eventually the ocean broke through and formed a narrow channel connecting Nauset Marsh and the pond. Source: Cape Cod National Seashore Site