ABSTRACT


 A bed of lignitic peat underlies an extensive area of Trail Ridge, in Bradford
and Clay counties, Florida. Trail Ridge is composed largely of heavy-mineral-
bearing quartz sand which was deposited as a beach ridge by a transgressing sea.
Fossil molluscs found within the sand suggest that the beach ridge is of Late
Pliocene or Early Pleistocene age. Palynological analysis of the lignitic peat
shows that small trees, shrubs, and aquatic herbs grew in a freshwater swamp
which stood adjacent to the accumulating sand ridge. Myrica, Ilex, Magnolia,
Gordonia, and Cyrilla are among the genera which indicate that the climate in
northern Florida was subtropical at the time of peat deposition. The palyno-
flora has a modern aspect, and supports the contention that Trail Ridge is of
post-Miocene age.

 ACKNOWLEDGEMENTS

 This author is indebted to E. I. du Pont de Nemours and Company and the
Florida Bureau of Geology for generously supplying the samples from Trail
Ridge. Mr. Tom Garnar, Jr., of du Pont, and Charles W. Hendry, Jr., of the
Florida Bureau of Geology, deserve special thanks. Drs. Fred Pirkle and Jesse
Yeakel provided information and samples which were critical to this project,
and reviewed the manuscript. They are gratefully acknowledged.
 Funding for this work was provided in part by the Coal Research Section of
the Pennsylvania State University and the South Dakota School of Mines and
Technology.