St. Marks Formation

The St. Marks Formation is a Miocene geologic formation in the eastern Florida Panhandle.

St. Marks Formation
Stratigraphic range: Miocene
Type	Rock sample from the St. Marks Formation
Unit of	None
Sub-units	None
Lithology
Primary	Limestone & sand
Location
Region	Florida Panhandle
Country	United States
Extent	Jefferson, Leon, and Wakulla counties
Type section
Named for	St. Marks River
Named by	J. Finch, 1823

St. Marks Formation location in red.

Age

Period: Neogene
Epoch: Miocene ~23.03 to 5.33 mya, calculates to a period of 17.7 million years
Faunal stage: Arikareean through Hemphillian

Location

The St. Marks Formation is exposed in Wakulla, southern Leon and southern Jefferson County, Florida on the northwestern flank of the Ocala Platform and along with Suwannee Limestone and Ocala Limestone makes up the upper part of the Floridan Aquifer in the eastern panhandle.^[1]

Composition

The St. Marks Formation consists of a white to yellowish gray, poorly to moderately hard, sandy, fossil bearing rock in molds and casts within packstone to wackestone.

Fossils

The fossils are in molds and casts and include:

• Mollusks