The Outer Banks of North Carolina are a slim and moving line of sand in the open Atlantic. Many travelers think they know these islands, but south of Ocracoke Inlet there rises a luminous bar of sand 60 miles in extent, with no roads, no bridges and no hotels. These are the wild beaches of Cape Lookout — one of the few remaining natural barrier islands in the world. At once an exaltation and elegy, Ribbon of Sand profiles this seascape and the transitory islands that are doomed to disappear. Meryl Streep reads excerpts from Rachel Carson’s writings.