Abstract: Origins of Florida Panhandle Terrace Sands

TANNER. W. F.
Florida State University;
JAMES H. BALSILLIE
Florida Geological Survey;
HOLLY K. WILLIAMS
Florida State University; all in Tallahassee, FL

Five new sand sample suites have been studied from the marine terrace system in and near Tallahassee, Florida. The 3 main terraces, at about 35,

50 and 80 m, were sampled earlier; the new suites were obtained at 20-50 m. Part of the earliest work, based on widely spaced samples, is shown not to be as useful as more recent study, during which each suite of samples was collected from a small area, probably representing a single depositional agency.

The basic procedure was granulometric analysis, using "suite statistics" methodology, which gives better results than work with individual samples. In addition, distinctive, diagnostic and reliable features appear in some instances on the probability plots of individual samples.

The general results include the following: (1, 2) Two Capital Circle localities, at 22-25 m elevation: unusually small grains (0.11 mm) representing first a river and a beach, and then later settling from water; (3) Fairview School locale, at about 25 m elevation: dune; (4) Campground Pond Road locality at about 37 m: a river not too far away: (5) Ocala Road site, at about 50 m: beach; plus the 80-m, 50-m., and 35-m terraces, each indicating a beach plus wind work. The wave energy level for the beach localities was low-to-moderate, as is observed today in the northeastern Gulf of Mexico.

The sands from the 35-50-80 m terraces show clearly: gradual fining of the mean grain size, and gradual worsening of the sorting (standard deviation becomes larger), as time passed.

AAPG Search and Discovery Article #90932©1998 GCAGS/GCS-SEPM Meeting, Corpus Christi, Texas