The extent and thickness of Jurassic strata in Alabama and Florida were mapped as part of a U.S. Geological Survey regional geohydrologic study. Rocks equivalent to the Werner, Louann, Norphlet, Smackover, Haynesville, and Cotton Valley sequences of Mississippi and Arkansas have been recognized and, except for the Werner equivalent, are herein extended into panhandle Florida. The predominantly fluvial Jurassic sequence in Alabama and Florida was interrupted at least twice by barred-basin conditions that resulted in the deposition of extensive evaporite deposits, and at least once, during deposition of the Smackover Formation, by a major marine transgression. The updip limits and isopach map trends of the Jurassic units mapped appear to have been controlled by a major nort west-trending, right-lateral wrench fault--the dominant master shear in a regional wrench-fault system active throughout Jurassic time.