The boundaries between Seashore lands, private property, and community facilities are not always obvious. The Provincetown airport and the Nauset Regional High School in Eastham, for instance, both lie within Seashore boundaries. Visitors are asked to observe the “Private Property—Please Respect Owner’s Rights” signs they encounter along many of the Seashore roads and trails. A number of the more popular beaches require local town parking stickers. Cape Cod National Seashore, in other words, is not so much a protected pristine preserve as an ongoing experiment in cooperation between the Federal Government and local communities and their residents who continue to live, work, and play alongside, and often within, the park itself. Whether you choose to join the summer crowds, or seek a solitary walk along the winter beach, we hope this handbook will acquaint you with enough knowledge of Cape Cod’s rich historic and natural heritage so that your visit here, whether brief or extended, will be more rewarding. [Illustration: (Pond with marshy shoreline.)] Part 2 A Great Arm in the Sea [Illustration: =Pages 20-21=: _This satellite view clearly shows the flexed arm shape of the Cape._] [Illustration: _Overwashes of sand become readily apparent from the air over North Beach off Chatham._] A Sliver of Sand From the air the great curled arm of Cape Cod looks like a mere film of sand, a whimsical momentary shape floating on the vast ocean around it. Its flimsy fabric appears torn and rent by hundreds of holes, large and small, and dozens of slits at the edges, where the water shows through. So sheer and vulnerable does it appear that it seems as if the slightest push might sink it beneath the sea. This somewhat fanciful impression nonetheless contains several grains of geologic truth, for water, in its various guises, permeates the Cape’s past, present, and future. Created by the frozen water of vast glaciers, shaped today by the water of tides, waves, currents, and storm surges, this prominent hook of land is destined to succumb at last to the steadily rising waters of the sea—all in the merest flick of geologic time. Some 75,000 years ago, when the Earth’s climate entered a cooling period, the most recent of the vast continental ice sheets, known as the Laurentide, began to form across eastern Canada. As it spread and thickened, much of the oceans’ waters became trapped in its mass, lowering sea levels by several hundred feet. The visible bulk of Cape Cod is primarily the work of the Wisconsin Stage Glacier, a towering wall of ice 10,000 feet thick that moved south over New England some 25,000 years ago. Grinding forward in rounded fronts, or lobes, the ice sheared off the tops of mountains, gouged huge valleys through granite hills, and plowed up tons upon tons of rocks, material, and debris from what had been the floor of the sea.