The ice has finally all melted, barring any late-winter freezes. With that, we begin the long-awaited transition to spring. There was a time, not long ago, when the warming air of summer would not melt the ice, and a layer of perma-frost covered all of what we call “New England” and much of the Earth. About 20,000 years ago, during the last “glacial maximum,” the Laurentide ice sheet stretched from Newfoundland to the Rocky Mountains and as far south as Ohio, at times fully encompassing New England in a mountain of ice. In some parts of New England, the ice was nearly a mile thick according to author/teacher Bradford B. VanDiver. Though that was primarily in Vermont/New Hampshire, with the thickest parts of the ice sheet, those being over two miles deep, being in Canada. In what is today the Tri-Town, the ice was likely a few thousand feet thick.
The Long Island Sound, Narragansett Bay, Buzzards Bay, and yes, the jagged coasts of the Southcoast were all formed under the crushing weight of the ice sheet and glaciers. Due to much of the Earth’s seawater being frozen within the glaciers and ice sheets, sea levels were far lower. This caused the coastline to be roughly 100 miles further out than it is today, easily making the areas of Block Island, Nantucket, and Martha’s Vinyard all part of the mainland. These islands, along with Cape Cod and the Elizabeth Islands, were all formed by sand and rock deposits from the retreating ice.
The Museum of Natural History’s Sidney Horenstein noted New York, at least, has risen roughly 150 feet following the retreat of the ice and the loss of its immense weight. The Earth’s crust still rises slowly to this day on its way back to equilibrium. Due to the slow melt-off of the ice sheet, New England escaped its grasp about 10,000 years ago.
Researchers still have much to uncover about the de-glaciation period, though much of what was caused by it can be easily spotted. Whether it be the region’s aforementioned unique coastline and it being ridden with bogs and small lakes, it is easy to look at a map of the area and envision the land being scraped away to its current form. As with the creation of the Cape and islands, the large number of rocks, pebbles, and boulders seen in many parks, woods, and yards were also deposited here by glaciers.
The melting of the ice allowed for the first humans to enter the region, following the caribou and looking for a new home. At that time, the area was rocky and sparce of vegetation aside from lichen and small plants with evergreen and oak forests populating the area not long after. It seems like a long time ago, but relatively speaking, all you see around you was buried under unfathomable tons of ice not long ago. Any time you find yourself in Marion’s Sippican Harbor, Mattapoisett Harbor, or nearby Rochester’s cranberry bogs, you can thank the Laurentide ice sheet for crushing the land, carving the coastline, and depositing sand and stones.
By Sam Bishop