2 | Let's go to the beach!
How are beaches created?
The most common type of shoreline in the Great Lakes region is the sand beach. Sand is deposited on beaches when the waves from the lake move it up from the lake bottom to the shoreline, and the sandy shorelines are ever changing. Littoral transport carries sedimentary material both parallel to the shore (longshore transport) and perpendicular to the shore (on-offshore transport). The wind can also transport sand, carrying both large and small grains and depositing them either up or downshore. Humans can also transport sand. For example, non-contaminated sand dredged from lake bottoms is sometimes added to a beach to increase its size or to replace beach sand that has eroded.
Why are beaches important?
Because the land and water are constantly meeting one another, many different life forms inhabit a beach, such as algae and other microfauna. Therefore, beaches are rich feeding grounds for migratory shorebirds. The beach also collects driftwood and other debris that a variety of beetles, spiders, and shorebirds like to feed upon. Shoals, sandbars, and spits often protect marshes and other wetlands from excessive wave and wind action. Spits, such as Long Point on Lake Erie and Oak Point on Lake Superior, may provide a habitat for plant and animal communities. And, of course, beaches are great places for us to go swimming!
What is sand made of?
Sand consists of rocks, crystals, and sea shells that are eroded over a long period of time by wind, water, and ice. The composition of sand can change greatly from beach to beach. For example, the black sand beaches of Hawaii are composed of volcanic ash and rocks, while the white beaches of the Caribbean consist of sea shells. The tan-colored beaches around the Great Lakes area are made up mostly of grains of quartz.
Although no longer located on a body of water, beach ridges are common in the Great Lakes region. These ancient ridges formed the seashores of the proglacial lakes, and were left behind as the lakes' levels dropped to their current elevations. The Ridges Sanctuary in Door County, Wis., contains 16 beach ridge formations. Another ancient beach ridge formation runs from the present day Maumee River, past Toledo, Ohio, and into southern Michigan.
See also GLIN's Beaches page, and BeachWatch, Recipe for a Beach
Graphics: beach at Frankfort, Michigan; sand sculpture; and, a sample of quartz