Bernard, Lafourche, the modern Mississippi, and now the Atchafalaya.
The sediments were carried from north to south by the Mississippi River.
The alluvial region includes low swamp lands, coastal marshlands and beaches, and barrier islands that cover about 20,000 square miles (52,000 km).
Their age and distribution can be largely related to the rise and fall of sea levels during past ice ages.
Much of the state's lands were formed from sediment washed down the Mississippi River, leaving enormous deltas and vast areas of coastal marsh and swamp.
These contain a rich southern biota; typical examples include birds such as ibis and egrets.
is a state in the southeastern region of the United States.
It is the 31st in size and the 25th most populous of the 50 United States. with political subdivisions termed parishes, which are the local government's equivalent to counties.