Gulf Coast of the United States Pensacola, St. Petersburg, Tampa, and increasingly, Sarasota. All are the centers of their respective metropolitan areas and contain large ports. (Baton Rouge is relatively far from the Gulf of Mexico; its port is on the Mississippi River, as is the port of New Orleans.) The Gulf Coast is made of many inlets, bays, and lagoons. The coast is also intersected by numerous rivers, the largest of which is the Mississippi River. Much of the land along the Gulf Coast is, or was, marshland. Ringing the Gulf Coast is the Gulf Coastal Plain which reaches from Southern Texas to the western
Gulf of Mexico basin on top, by siliciclastic, eolian, playa and other sediments characteristic of arid terrestrial environments closer to shore, implying that at certain times during deposition, sediments accumulated almost up to sea level. The salt structures, which include anticlines, pillows, plugs and walls, in addition to extensive sheets, were created long after deposition by the rapid overlying sedimentation. Nearer the depocenter, which for the Gulf of Mexico basin was towards the spreading center, terrestrial sediments grade into marine shales and limestones. Post salt deposition, the strata recorded millions of years of marine flooding sediments, carbonates from coral reefs, thick sandstones, and eventual