East and ahead of the coast of North America, some thirty miles and more from the inner shores of Massachusetts, there stands in the open Atlantic the last fragment of an ancient and vanished land. For twenty miles this last and outer earth faces the ever hostile ocean in the form of a great eroded cliff of earth and clay, the undulations and levels of whose rim now stand a hundred, now a hundred and fifty feet above the tides. Worn by the breakers and the rains, disintegrated by the wind, it still stands bold. Many earths compose it, and many gravels and sands stratified and intermingled. It has many colours: old ivory here, peat here, and here old ivory darkened and enriched with rust. At twilight, its rim lifted to the splendour in the west, the face of the wall becomes a substance of shadow and dark descending to the eternal unquiet of the sea; at dawn the sun rising out of ocean gilds it with a level silence of light which thins and rises and vanishes into day. At the foot of this cliff a great ocean beach runs north and south unbroken, mile lengthening into mile. Solitary and elemental, unsullied and remote, visited and possessed by the outer sea, these sands might be the end or the beginning of a world. Age by age, the sea here gives battle to the land; age by age, the earth struggles for her own, calling to her defence her energies and her creations, bidding her plants steal down upon the beach, and holding the frontier sands in a net of grass and roots which the storms wash free. The great rhythms of nature, to-day so dully disregarded, wounded even, have here their spacious and primeval liberty; cloud and shadow of cloud, wind and tide, tremor of night and day. Journeying birds alight here and fly away again all unseen, schools of great fish move beneath the waves, the surf flings its spray against the sun. Often spoken of as being entirely glacial, this bulwark is really an old land surfaced with a new. The seas broke upon these same ancient bounds long before the ice had gathered or the sun had fogged and cooled. There was once, so it would seem, a Northern coastal plain. This crumbled at its rim, time and catastrophe changed its level and its form, and the sea came inland over it through the years. Its last enduring frontier roughly corresponds to the wasted dyke of the cliff. Moving down into the sea, later glaciations passed over the old beaches and the fragments of the plain, and, stumbling over them, heaped upon these sills their accumulated drift of gravels, sand, and stones. The warmer sea and time prevailing, the ice cliff retreated westward through its fogs, and presently the waves coursed on to a new, a transformed and lifeless, land. So runs, as far as it is possible to reconstruct it in general terms, the geological history of Cape Cod. The east and west arm of the peninsula is a buried area of the ancient plain, the forearm, the glaciated fragment of a coast. The peninsula stands farther out to sea than any other portion of the Atlantic coast of the United States; it is the outermost of outer shores. Thundering in against the cliff, the ocean here encounters the last defiant bulwark of two worlds.