Beach Treasures

Beaches form along the shoreline of a body of water where waves and currents deposit and rework sand, gravel, pebbles, cobble, and shell fragments, while longshore drift gradually moves loose sediment sideways along the shore. These unstable environments are continually altered by wind, waves, and erosion, and many kinds of material wash ashore. Among them are rocks and boulders carried here about 65,000 years ago by glaciers from the Canadian Shield; these glacial erratics differ from the nearby bedrock and are composed of igneous and metamorphic rocks, primarily granite and gneiss, often showing white, red, and black colors. The local bedrock in this region is sedimentary, mainly dolostone, shale, limestone, and sandstone, and only sedimentary rocks and glacial erratics are found on this beach. Freshwater clam shells also wash up here, with dull gray outer surfaces for camouflage and lustrous multicolored interiors against a pearly white background. Some things that wash ashore are not natural, including beach glass formed when broken bottle and jar fragments enter the lake as litter and are churned smooth and frosted by water and sand. Zebra and quagga mussels, invasive species native to the Caspian Sea, probably reached the United States in the ballast water of ocean-going ships; they attach to hard submerged surfaces, clog pipes in power plants and water treatment facilities, damage harbors by covering docks, boats, break walls, and buoys, and are difficult to control because they reproduce rapidly and have no natural predators. Driftwood, coming from trees, buildings, ships, or other wooden objects washed into the water, eventually decomposes and drifts back to shore, where it can provide shelter for birds, plants, and other species.

Wilson, New York · United States