Arcadia Formation

It is thin or absent along the east coast of the Florida peninsula north of Indian River County.

It is buried beneath later formations over most of its extent, with the exception of surface exposures in the area around Tampa Bay (in Hillsborough, Manatee, and Pasco counties).

The texture is micro to finely crystalline with varying sandy, clayey limestones and dolomites containing phosphate.

[7] The Arcadia Formation developed when sea levels rose to flood much of the Florida Platform late in the Oligocene epoch.

During the Aquitanian faunal stage (early in the Miocene), extensive upwelling around the Florida Platform carried plankton into the Okeechobean Sea and Tampa Subsea, depositing phosphorus-rich carbonate layers in the basins.

It is fossil bearing and variably sandy and clayey mudstone, wackestone, and packstone with little to no phosphate grains.

The fossil beds of the Tampa Member have since been studied by William Healey Dall, Gilbert Dennison Harris, and Angelo Heilprin, as well as others.

In 1964, H. S. Puri and R. O. Vernon classified the Early Miocene strata in Florida as the "Tampa Stage", consisting of the Chattahoochee and St. Marks formations.

[16] Erosion has removed the Tampa Member north of Hillsborough County leaving only a few isolated remnants.

The Floridan Aquifer extends throughout Florida and most of the coastal plain in Georgia, as well as small adjacent areas in Alabama and South Carolina.

As does the Arcadia Formation, the aquifer slopes and becomes thicker from north and northeast to south and southwest.

The Tampa Member contains mollusks and corals in molds and casts with silicified pseudomorphs and shell material.