Gulf of Mexico Gulf of Mexico The Gulf of Mexico () is an ocean basin and a marginal sea of the Atlantic Ocean, largely surrounded by the North American continent. It is bounded on the northeast, north and northwest by the Gulf Coast of the United States, on the southwest and south by Mexico, and on the southeast by Cuba. The U.S. states of Texas, Louisiana, Mississippi, Alabama, and Florida border the Gulf on the north, which are often referred to as the "Third Coast", in comparison with the U.S. Atlantic and Pacific coasts. The Gulf of Mexico formed approximately 300 million years
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