_As the Buzzards Bay, Cape Cod Bay, and, perhaps, the South Channel glacial lobes waned, they left behind moraines (above right). Meltwater streams carried sand and gravel that then formed outwash plains beyond the ice (above and below). Sometimes these materials buried large blocks of ice. In time, the ice blocks melted, leaving steep-sided depressions called kettles that became freshwater ponds if they were deep enough to intersect the water table. Some of these ponds became connected to the sea and turned into salt ponds, such as the one near the Seashore visitor center in Eastham. Over the years peat has filled in many of the ponds._ ############################################# The Restless Shore [Illustration: (Beach erosion. Destroyed beach houses. Parabolic sand dunes.)] Within a person’s lifetime, the Cape’s shape changes dramatically. The waters of the ocean and bay and the wind constantly erode material here and deposit it there. Major storms can create islands, sandbars, and dunes and revamp other land forms. A storm in 1931 weakened playwright Eugene O’Neill’s home—the old Peaked Hill Bars Coast Guard Station—and sent it into the ocean in 1932 (below). Summer winds generally come from the west or southwest. In the winter, the most severe winds come from the northwest or northeast. The Outer Cape as a whole is moving westward and diminishing as these forces tear at the landscape and as ocean currents move sand northward and southward from about the Marconi Station Site. For every 5 acres of sand eroded, about 2 acres are deposited up or down the coast, thereby elongating (see map at right) the hook at Provincetown and North Beach and Monomoy Point off Chatham. On the bay side, sands have extended Jeremy Point southward to a point almost directly west of Marconi Beach. An 1889 U.S. Coast and Geodetic Survey report says that the entire Outer Beach from 1848 to 1888 lost 323,233,030 cubic yards of earth and sand, enough to cover the 55-acre U.S. Capitol grounds to a depth of 375 feet. Similar changes are taking place today. Some residents have seen North Beach, the southern extension of Nauset Beach, lengthen itself from just south of Orleans to Chatham and then break in 2 pieces in a fierce northeaster in 1987. The breach, which has grown to more than a mile in width, has opened Chatham’s shoreline to the full force of ocean storms, increasing erosion and claiming more than a dozen houses (inset below). But the breach has also increased tidal flushing of Pleasant Bay, reinvigorating the marine community. In November 1991, a 4-day gale breached the dune line at the head of the Pamet River, carrying sand and saltwater 500 feet into the river. _Parabolic sand dunes occur on the narrow stretch of land east of Pilgrim Lake in the Province Lands of Truro. Prevailing northwest winds blow obliquely to the shoreline and create belts of these unusual dunes with the sands of former beaches_.