Southeastern Massachusetts, Cape Cod, and the islands of Nantucket and Martha's Vineyard consist of outwash from the last glacial maximum, which left thick glacial deposits of sand and gravel, providing the geologic foundation for a rare pine barren ecosystem.
The southeastern region of Massachusetts, including Cape Cod and the islands of Nantucket and Martha's Vineyard, is built upon glacial outwash from the most recent ice age. This deposit of sand and gravel created a rare pine barren environment.