ABSTRACT

The lithostratigraphy of the Miocene section in southwestern Florida has been a source of confusion and discussion for many years. Historically, the Miocene section in this area consists of, in ascending order, the Tampa Limestone (Formation), the Hawthorn Formation, and the Bone Valley Formation. Areally, the Tampa underlies portions of 8 counties, the Hawthorn underlies almost the entire area, and the Bone Valley occurs in limited parts of two counties. The Tampa grades laterally into the basal Hawthorn carbonate section to the east and south. Much of the Bone Valley changes laterally into the upper Hawthorn clastic section. As a result of these relationships and the complex nature of the Hawthorn it is suggested here that the Hawthorn be upgraded to group status. The basal Hawthorn Group would be referred to as the Arcadia Formation with the Tampa included as a member within it. The upper Hawthorn Group would be referred to as the Peace River Formation and the Bone Valley ranked as a member within it.

The suggested revision of the Miocene section allows better understanding of the Miocene geologic history of southwestern Florida. It also provides a lithostratigraphic framework which will allow the extension of the Hawthorn Group throughout central and south Florida.