Core samples from deep boreholes in panhandle Florida form the basis of a basement model involving at least eight separate fault blocks and basins, each with a distinct depositional history. The dominant structures are a northwest-trending fault and a large, northeast-trending Triassic graben which encompasses several secondary fault blocks and forms the Southwest Georgia Embayment (Apalachicola Embayment). This graben as well as associated perpendicular (northwest-southeast) faults were formed in response to tensional forces related to the Mesozoic separation of North American and South American landmasses and the consequent formation of the Gulf of Mexico. Granitic basement blocks, perhaps early Cambrian in age, experienced differential subsidence and changing relations ips with various sedimentary source terranes. Thus, the separate basins accommodated different combinations of Triassic Eagle Mills red beds and Jurassic deposits ranging from the Louann Salt to the Cotton Valley sandstones and shales.

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