Alternating fresh- and brackish-water and marine shell marls and limestones, typically exposed at Fort Thompson [just above LaBelle, Hendry Co.], just below Goodno's Landing. Relations to Miami oolite not determined. Underlies Coffee Mill Hammock marl. Age is Pleistocene.

Source: GNU records (USGS DDS-6; Reston GNULEX).

Hialeah Group (DuBar, in press) [unpub. ms.] is composed of the late Pleistocene Fort Thompson Formation, Anastasia Formation, Miami Limestone, and Key Largo Limestone. Formations intergrade and interfinger, especially in southeastern FL. Fort Thompson is further divided into the Okaloacoochee and Coffee Mill Hammock Members. The Fort Thompson unconformably overlies the Bermont or Caloosahatchee Formation of the Port Charlotte Group or the Sarasota Formation of the Tamiami Group and unconformably underlies the Lake Flirt Formation or equivalents. Sangamonian age is based on Th234/U238 ages of 120 and 140 ka and by mollusks from the Coffee Mill Hammock Member.

Source: GNU records (USGS DDS-6; Reston GNULEX).

Coffee Mill Hammock is retained as a separate unit of formation rank overlying the Fort Thompson Formation. Other workers have included the Coffee Mill Hammock as a member of the Fort Thompson. Age of the Coffee Mill Hammock has been determined at 0.13 to 0.11 Ma. Further work is needed to define the age and stratigraphic extent of the Fort Thompson. Overlies Bermont Formation (early Pleistocene.)

Source: GNU records (USGS DDS-6; Reston GNULEX).