The coring of deep-water sediments in the Gulf of Mexico during Legs I and X of the JOIDES program has contributed significantly to our knowledge of the Gulf's geologic history. The nature of Sigsbee scarp is still not known with certainty, but the results of drilling holes 1 and 92 suggest that both "contemporaneous normal faulting" (perhaps overbuilding and downslope movement) and salt tectonics may be involved.

Drilling results from holes 3, 85, 87, 90, and 91, indicate that formation of the present Sigsbee plain includes late Neogene subsidence and, prior to the Pliocene, a more westerly source for coarse terrigenous clastic debris than the Mississippi River. The discontinuous record of deep-water sedimentation since the end of Early Cretaceous time, found in holes 86, 94, 95, 96, and 97, suggests a complex structural history of block tilting and faulting for the banks and scarps. This may include a Late Cretaceous seaway, and its reemphasis as the present Yucatan Channel-Florida Strait as late as Pleistocene. Correlatibility of the discontinuities bounded above and below by deep-water sediments may require some more comprehensive explanation than slumping and submarine current removal of s diments.

Perhaps worthy of note, is the possibility that the overly publicized recovery of hydrocarbons from Challenger Knoll in the Campeche embayment salt-tectonic province (hole 2) affected the extenders of the JOIDES program, thus helping to make Leg X cruise possible. Drilling during this cruise, in turn, under the influence of changing political winds, contributed to the pollution-scare, thwarting the original Leg X goals. Many of our basic questions have not been answered adequately by JOIDES work, but we are, at least, aware of many more questions.

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