FLORIDA GEOLOGICAL SURVEY


Wingard et al., 1997; Missimer, 1997). The Tamiami Formation is Early to Late Pliocene
(Missimer, 1997).
 The Miocene lithostratigraphic units recognized by this study in the panhandle include
the Chattahoochee Formation, St. Marks Formation, Alum Bluff Group, Torreya Formation
(Hawthorn Group) and residuum. In the peninsula, the Miocene units mapped include the
undifferentiated Hawthorn Group, Coosawhatchie Formation, Charlton Member, and the Peace
River Formation and its Bone Valley Member.

 Tch Chattahoochee Formation The Chattahoochee Formation, originally named by
Dall and Stanley-Brown (1894), is predominantly a yellowish gray, poorly to moderately
indurated, fine-grained, often fossiliferous (molds and casts), silty to finely sandy dolostone
(Huddlestun, 1988). Siliciclastic beds and limestones may be present.
 The Chattahoochee Formation is exposed in Jackson County, central panhandle, on the
Chattahoochee "Anticline". It grades laterally across the Gulf Trough into the St. Marks
Formation through a broad transition area (Scott, 1986). The Chattahoochee Formation forms
the upper part of the FAS in the central panhandle.

 Tsmk St. Marks Formation The Lower Miocene St. Marks Formation, named by
Finch (1823), is exposed in Wakulla, Leon and Jefferson Counties on the northwestern flank of
the Ocala Platform. It is a white to yellowish gray, poorly to moderately indurated, sandy,
fossiliferous (molds and casts) limestone (packstone to wackestone). Mollusk molds and casts
are often abundant. The St. Marks Formation makes up the upper part of the FAS in part of the
eastern panhandle.

Hawthorn Group
 The Hawthorn Group in Florida is composed of a number of different formations and
members (Scott, 1988; Huddlestun, 1988). Most of the formations are defined from subsurface
evaluations. As a result, for mapping purposes, all the component formations are not recognized
on the geologic map.
 In the eastern panhandle, the upper Lower Miocene Torreya Formation, including the
Dogtown and Sopchoppy Members (Huddlestun and Hunter, 1982), comprises the entire
Hawthorn Group (Scott, 1988). The Dogtown and Sopchoppy Members are not delineated on
the map.
 In northern peninsular Florida, the Hawthorn Group consists of the lower Lower Miocene
Penney Farms Formation and, rarely, the Parachucla Formation; the upper Lower Miocene
Marks Head Formation; the Middle Miocene Coosawhatchie Formation and the Statenville
Formation (Scott, 1988; Huddlestun, 1988). The Charlton Member of the Coosawhatchie
Formation is recognized in a limited area. The Penney Farms and Marks Head Formations are
not recognized cropping out in significant exposures. The undifferentiated Hawthorn Group was
mapped where component formations were questionable or difficult to differentiate due to very
limited data.
 In southern peninsular Florida, the Hawthorn Group formations include the Upper
Oligocene to Middle Miocene Arcadia Formation including the Tampa and Nocatee Members
and the Middle Miocene to Early Pliocene Peace River Formation with its Bone Valley Member
and Wabasso beds (Scott, 1988). The Nocatee Member of the Arcadia Formation and the