The recent studies presented by Schmalz indicate that it is possible for significant thicknesses of salt to be deposited in a deep-water environment. This hypothesis makes it possible to propose a relatively simple model for the Gulf of Mexico which accounts for the distribution of the deep-water salt structures including the Sigsbee Knolls, the diapiric structures on the northern continental slope, and possibly the anticlines of the western Gulf. However, most recent geophysical data indicate that a thick salt layer is not present across the Gulf of Mexico basin. These data suggest that the Sigsbee scarp represents the southernmost extent of the salt of the northern Gulf region and that the trend of the Sigsbee Knolls and domes is the northern extent of the migration of alt from south Mexico.

On the basis of the assumptions that the Gulf of Mexico is an old basin and that our interpretation of the new data is correct, an alternate hypothesis is proposed to explain the salt-structure distribution. It is suggested that the following series of events took place: (1) salt was deposited along the marginal areas of the basin; (2) sediment accumulated above the salt and subsequently subsidence occurred; (3) salt ridges and stocks formed and salt migrated downdip into the deeper parts of the basin, as a result of overburden pressures; and (4) in areas of carbonate buildup, competency of the carbonate material prevented formation of salt piercement structures; instead, horizontal migration of salt toward the deep basin seems to have taken place.