Dredging, coring, and arcer profiling of the Florida escarpment southward from 28°1.5^primeN, 86°24^primeW, to the Florida Strait, of Jordan Knoll (23°20^primeN, 83°45^primeW) in the Florida Strait, and of the Campeche escarpment northeast of Yucatan (23°39^prime-23°45^primeN, 85°22^prime-85°26^primeW) have revealed the presence in all three areas of late Aptian-Albian reef and forereef facies which lithologically and paleontologically are nearly identical to the Glen Rose-Stuart City reefs of the U.S. Gulf Coast and the El Abra-Golden Lane reefs of eastern Mexico. The late Aptian-Albian reefs--or banks--apparently were not continuous from the Florida escarpment to the Campeche escarpment, but were separated by a deep-sea channel wh ch crossed Pinar del Rio Province, western Cuba. Jordan Knoll may have been an Early Cretaceous atoll, isolated from the reefs of the Florida escarpment and similar to the Golden Lane atoll of eastern Mexico.

A core from Jordan Knoll penetrated a late Pliocene carbonate mud containing abundant angular limestone clasts up to 2.1 cm in diameter. The clasts range in age from late Aptian-Albian through middle Miocene to early Pliocene. The source of the clasts is unknown but regional geologic data eliminate a southern source; the clasts most probably were derived from Jordan Knoll itself.

The lithology and paleontology of the clasts show that the Jordan Knoll region was a shallow-water bank until latest Albian or early Cenomanian time; that the present Florida Strait area deepened steadily from Cenomanian through Santonian times; and that, from Santonian time until the present, bathyal conditions generally prevailed. The knoll may have been uplifted during middle Eocene time as a result of the "Laramide" deformation of Cuba.

The eastern Gulf of Mexico has had a complex geologic history since Early Cretaceous time or before; the geologic data from Cuba, Yucatan, Florida, and our samples reveal some of this complexity, and suggest that the site of the Florida Strait has shifted through time. Much of the complexity is related to middle Cretaceous and "Laramide" tectonic events in Cuba. An understanding of the tectonic and stratigraphic history of South Florida, the Florida Strait, and the Campeche (Yucatan) platform ultimately may lead to the discovery of substantial petroleum accumulations in this region.