Glacial oddities abound in New England. The glaciers—miles thick in places—depressed the land beneath so that when the ice melted the land was lower and the sea poured in to cover it. The St Lawrence River, connected to Vermont's Lake Champlain, was a broad inlet of the Atlantic for a time, inhabited by ocean-going creatures. This explains why, in 1848, railroad builders came upon the skeleton of a whale on dry land in a 10,000-year-old layer of clay in Charlotte VT, south of Burlington VT.
Though most of what you see as you travel around New England was formed by glaciers, in a few places evidence of much older geologic ages pokes through the glacial mess. The strongly-colored clays of Aquinnah (Gay Head) on Martha's Vineyard are a fragment of sediments from the Cretaceous Period (around 100 million years ago).
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