The Texas Coastal Plain, a strip about a hundred miles wide extending from Nueces Bay to Galveston Bay, is underlain by sedimentary strata of Mesozoic (Lower and Upper Cretaceous) and Cenozoic age. These beds are mainly unconsolidated, and as a rule they dip gently toward the Gulf. The Upper Cretaceous strata outcrop along the interior portion of the Coastal Plain and extend to the Gulf in the subsurface; the remainder of the Coastal Plain is underlain by Tertiary and Pleistocene deposits, the latter lying immediately interiorward from and bordering the Gulf of Mexico. Topographically, the Coastal Plain consists of three major physiographic divisions or belts that extend more or less parallel to the Gulf Coast. These divisions include: (a) the interior belt, consisting of an inner lowland plain that was sculptured out of the outcropping softer beds of the Upper Cretaceous; (b) the coastal belt, a low, flattish country, bordering on the Gulf of Mexico and underlain by the Beaumont clays and the Lissie formation, both of Pleistocene age; and (c) the intervening broad belt underlain mainly by sands and nonlimy clays, comprising the Central Dissected Belt. East of the Mississippi River, this intervening zone is often referred to as the Central Sandy Belt; in Texas, however, it has a few outcropping limy clay areas that are important agriculturally. Climatically, the Coastal Plain of Texas is divided into three major groups: the humid plains of forested East Texas, the moderately humid prairies, including the Black Prairies, and the subhumid plains of South Texas.