Lending from one of the movie titles played at the Cape Cod National Seashore’s Salt Pond Visitor Center, the Cape Cod landscape is dynamic. Highly influenced by time and the hands of Mother Nature, this outreached flexing arm we call the Cape Cod Peninsula was formed by the retreat of glaciers. 20,000 years ago a continental ice sheet covered what we know as New England. It scoured the surface of the earth and picked up debris along the way south, from New England and the Gulf of Maine. Then, about 15,000 years ago, the glacier withdrew a short distance, with large deposits of debris left at the terminal moraine, forming Martha’s Vineyard and Nantucket. Over a period of about a 1000 years, the glacier retreated and advanced. With this movement, the fresh debris of the outwash plain, was pushed into the land, shearing it into layers. With the final retreat of the glacier, this uplifted land formed from the glacier’s terminal moraine and outwash plain created the bowed shape of Cape Cod Peninsula and the glacial lake bed – Cape Cod Bay. As the climate warmed, the sea level rose rapidly and the North Atlantic began to sculpt the seashore of the Cape and continues to shape it today.
Ever since the rise of the sea from the melting of the glaciers, this vulnerable piece of seashore has been battered by the North Atlantic every winter for 6,000 years. During winters, the waves of the beach are rougher – hitting the seabed harder and washing away more sand. In the spring, the waves are gentler and usually redeposit the sand back ashore – but sometimes the landscape has been so drastically changed and eroded in the winter, the erosion outweighs the deposition. When gale force winds elevate high tides to even higher tides, more damage is caused and more destruction created. On Cape Cod, the coastline retreats about an average of 3 feet each year, with some elevated erosion statistics on other areas of the Cape. For instance, the Eastham bluffs are estimated to erode about 5-10 feet each year, creating serious problems for the manmade structures along the seashore.
However, not all of the Cape is eroding away – some of the Cape is growing. The sand from the eroded seashores of the North are being carried down the coast by littoral drift currents and depositing the sand at the Southern points of the Cape. These changes to the Cape can’t be stopped, as Mother Nature runs her course.
Stay tuned for more visuals and information on this matter in a short video on Cultural Landscapes: The Ever-Changing Cape Cod National Seashore.