Glacial deposits of Outer Cape Cod are mainly of stratified drift occurring in three units: sand and gravel at the top, a silt-clay layer in the middle, and more sand and gravel at the bottom. These deposits contain shells and other marine materials picked up by the glacial ice as it moved across the Gulf of Maine and Cape Cod Bay. A C14 date for shells collected above the silt-clay was 20,700 ± 2000 years old, for those collected below the silt-clay, 26,900 ± 700 years old. It is proposed that the glacial material of Outer Cape Cod is entirely Wisconsin in age and that the silt-clay sediments represent a slight period of warming. All the stratified drift was presumably deposited subaerially or in temporary shallow pools formed on the local drift surface.