Preliminary results of a long-term program to investigate the tectonic history of the Gulf of Mexico are summarized principally through multichannel seismic reflection methods. Knowledge of the deep part of the Gulf contributes significantly to understanding the evolution of its continental margins. Reasonable and usual stratigraphic principles, based on marine reflection data, can be used successfully to interpret the geological history of such regions.

The stratigraphic unit which contains the Late Jurassic salt responsible for the diapirs of the deep Gulf of Mexico can now be recognized throughout this region, and diapirs have now been located as far east as the base of the West Florida Escarpment. Basement structural arches which seem responsible for the reef growth controlling the Florida and Campeche scarps are also present in the Yucatan Straits. All post-Jurassic units of the deep Gulf pinch out by depositional overlap against the Florida Escarpment to the east, against the Campeche Escarpment to the south, and against the newly discovered basement feature in the Strait of Florida. There is no evidence of faulting associated with these scarps.

The post-Jurassic through Miocene sediments of the deep Gulf originally continued north of the Sigsbee scarp, and completely across the Mexican Ridges to the west. Deformation by detachment sliding and diapirism progressed southward on the United States margin throughout the Cenozoic and occurred suddenly in the folded Mexican Ridges in late Pliocene or Pleistocene time. There is no evidence in the deep Gulf of Mexico of pre-Pleistocene deep-sea cones. The large deep-sea cone of the present Mississippi River is a prominent and unique feature of the Gulf.