The data from numerous seismic refraction profiles are presented in the form of five cross sections and three isopach maps. The specific areas covered are (1) the continental shelf south of Galveston, Texas, and (2) the continental shelf south of the Florida Panhandle. The area south of Galveston is represented by one cross section. This section shows the continuation seaward of the south-dipping sedimentary beds of the Texas Gulf Coast to a point approximately 60 km. south of Galveston where a reversal of dip is noted. At this point, presumably the axis of the Gulf Coast geosyncline, there are 13 km. of post-Cretaceous sediments. A broad ridge between the geosyncline and the Sigsbee scarp is shown. In the area south of the Florida Panhandle, four cross sections and three isopach maps show the relationship between the known onshore structure and the structure of the shelf. A continuation seaward of the Apalachicola embayment is noted and the great thickening of the Lower Cretaceous is shown to continue approximately 20 km. south of the present shoreline.

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