Geography of The Interior United States - The Gulf Coastal Plain

The Gulf Coastal Plain

The westward extension of the Atlantic Coastal Plain around the Gulf of Mexico has certain features that were already described and several new ones. As in the Atlantic coastal plain, it is only the lower, seaward part of this region that deserves the name of plain, for there alone is the surface unbroken by hills or valleys. The inner part, initially a plain, has been maturely dissected into an elaborate complex of hills and valleys, usually of increasing altitude and relief as one passes inland. The Gulf Plain features not found in the Atlantic coastal plain are:

• the peninsular extension of the plain in Florida
• the belted arrangement of relief and soils in Alabama and in Texas
• the Mississippi embayment or inland extension of the plain half-way up the course of the Mississippi River to its junction with the Ohio River at Cairo, Illinois, with the Mississippi flood plain there included.