fed by sandy and pebbly sediments eroded from headlands, especially ones with a thick covering of glacial material.

Several processes erode the coastline and transport sediment to marshes, mud flats, and beaches. One of the most important is longshore drift (also known as littoral drift), which works as follows: When a windy weather system moves into the area, the gusts whip up waves that pound the shore and stir up sediment. If the waves roll straight into the shore, the agitated sediment settles back down in more or less the same position it held earlier. But if the wind drives the waves in at an angle to the shoreline, the surf tends to carry sediment down the coast. Since weather follows patterns, an overall direction of longshore drift prevails in most areas, causing shoreline features to grow in that direction. This can be seen most dramatically in the growth of spits like Griswold Point, which inch by inch is stretching west across the mouth of the Connecticut River.

Wind itself is a mover of sediment, especially on beaches. Like waves, it too follows patterns that lead to an overall movement of particles in one direction at a particular location. Similar to waves of water, wind whips sediment into waves of sand called dunes. Over time, each dune moves slowly along the beach crest, just above the reach of high tide. In Connecticut, dunes tend to be less dramatic than in some other areas, in part because beaches here are smaller. But each of Connecticut's sand beaches has a line of dunes, important nesting grounds for Least Terns and other rare shore birds.

Tide, too, can alter the coastline. Because of the narrow passageways between Long Island Sound and the open ocean, the changing tide sets off some fairly strong currents. Currents are worst at Hell's Gate, the tight exit by New York City that churns with whirlpools. The channel at Hell's Gate has been deepened in recent times in an effort to make it safer for navigation, but currents still are swift enough that construction of a tidal-power generating plant across part of the passage has been

proposed. Through The Race between Fishers and Long Islands, currents are not nearly so powerful but nevertheless reach speeds of up to five knots, reversing direction twice a day as the tide rises and falls. The strong flux of water through Hell's Gate and The Race touches off

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