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A satellite image shows the peninsula of Cape Cod and the islands of Nantucket and Martha's Vineyard.
Cape Cod is a place of ocean and dunes - a place shaped by water and wind.
Waves crash against the shore.
Some dunes are partially anchored by vegetation.
But many grow and move freely with the wind.
Longshore currents produce slender spits of sand. The end of one spit projects from the right side of this picture.
Sheltered from waves, a tidal flat may form behind a spit.
Much of the material composing Cape Cod originated as outwash deposits from northern glaciers.
Coarse-grained outwash gravels remain in some places.
Waves have cut steep cliffs in these deposits on the oceanward side of Cape Cod.
A barrier island protects part of the shore.
But a break in the barrier island allows wind-driven ocean waves to reach the shore.
Inhabitants pile up boulders to prevent coastal erosion.
They're not always successful: compare preceding picture with this one to see that one house has disappeared - a victim of the forces of erosion.
Provincetown, MA, lies sheltered on the landward side of Cape Cod.
The Pilgrims' Monument is a prominent landmark in the town.
From the Monument, one can see a vista encompassing Provincetown, Cape Cod, and the Atlantic Ocean.
The Cape Cod Lighthouse warns ships of dangerous waters.
Silhouette of a wrecked ship gives mute witness that not all heed the warning