the visible lowland peninsula of Florida. The submerged half extends westward under the shallow Florida overlapping waters of the Gulf of Mexico. The northern part of the peninsula is composed largely of a weak limestone. Here, much of the lowland drainage is underground forming many sinkholes (swallowholes). Many small lakes in the lowland appear to owe their basins to the solution of the limestones. Valuable phosphate deposits occur in certain districts. The southern part of the state includes the Everglades, a large area of low, flat, marshy land, overgrown with tall reedy grass. The eastern coast is fringed by long-stretching sand reefs, enclosing lagoons so narrow and continuous that they are popularly called rivers. At the southern end of the peninsula is a series of coral islands, known as the Florida Keys. They appear to be due to the forward growth of corals and other lime-secreting organisms towards the strong current of the Gulf Stream from which they obtain their food. The western coast has fewer, shorter off-shore reefs. Much of it is of minutely irregular outline. Alabama – Mississippi belted plain A typical example of a belted coastal plain is found in Alabama and the adjacent part of Mississippi. The plain is here about wide. The basal formation is chiefly a weak limestone, which has been stripped from its original Alabama innermost extension and worn down to a flat inner lowland of rich black soil, thus gaining the name of the black belt. The lowland is enclosed by an upland or escarpment, known as Chunnenugga Ridge, sustained by partly consolidated sandy strata. However, the upland is not continuous, but a maturely dissected escarpment. It has a relatively rapid descent toward the inner lowland, and a very gradual descent to the coast prairies, which become very low, flat and marshy before dipping under the Gulf waters, where they are generally fringed by off-shore reefs. Mississippi embayment The coastal plain extends inland on the axis of the Mississippi embayment. Its inner border affords admirable examples of topographical discordance where it sweeps northwestward square across the trend of the piedmont belt, the ridges and valleys, and the plateau of the Appalachians. All of which are terminated by dipping gently beneath the unconformable cover of the coastal plain strata. In the same way the western side of the embayment, trending south and southwest, passes along the lower southeastern side of the dissected Ozark