SWAMP, a tract of wet, spongy, low-lying land, usually over grown with vegetation, but too highly saturated with water to be fit for agricultural or pastoral purposes. The term swamp, how ever, is often indiscriminately applied to various wet, watery or miry places, as a marsh or a bog or, as in Australia, a shallow pond or lake. But as more commonly understood, especially in the United States, where the word first came into recorded use (early in colonial days), a swamp is an area of very moist or wet ground, with luxuriant vegetation, and largely free from standing water. It thus differs from a marsh, which is covered for the most part with a thin sheet of water. A swamp differs in a correspond ing degree from a bog, which is a very wet, water-logged area, practically without drainage, in which extensive decomposition of vegetable matter is taking place, forming in northern latitudes deposits of peat (q.v.). A marsh or a bog may occur within or may border upon a swamp, with various intermediate stages in each case ; hence the frequent interchange in meaning between these terms in popular usage.
The character of the vegetation in swamps varies with the nature of the soil and the extent of drainage. Usually swamps are filled with a dense growth of coarse grasses, trees and shrubs. Swamps are found on the shoreward side of tidal marshes along seacoasts and near inland lakes and ponds with low shores; swamps are common also in the alluvial valleys of rivers and smaller streams. Among swamps possessing marked historical as well as scientific interest are those in the Campagna near Rome, and those found in the Pripet marsh region in western Russia. Noteworthy swamp areas in the United States are the Great Dismal swamp in south-eastern Virginia, the cypress and the mangrove swamps of the Southern States, and the "tule" swamps of the San Joaquin valley in California. Vast swampy and boggy areas in northern Canada are known by the Indian name muskeg.