St. Marks Formation
title: "St. Marks Formation" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["neogene-florida", "miocene-united-states", "miocene-series-of-north-america", "geologic-formations-of-florida", "paleontology-in-florida"] topic_path: "philosophy" source: "https://en.wikipedia.org/wiki/St._Marks_Formation" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0
::data[format=table title="Infobox Rockunit"]
| Field | Value |
|---|---|
| name | St. Marks Formation |
| image | [[File:St. Marks Formation.jpg |
| type | Rock sample from the St. Marks Formation |
| age | Miocene |
| prilithology | Limestone & sand |
| namedfor | St. Marks River |
| namedby | J. Finch, 1823 |
| region | Florida Panhandle |
| country | United States |
| unitof | None |
| subunits | None |
| extent | Jefferson, Leon, and Wakulla counties |
| :: |
| name = St. Marks Formation | image = [[File:St. Marks Formation.jpg|250px]] | type = Rock sample from the St. Marks Formation | age = Miocene | prilithology = Limestone & sand | otherlithology = | namedfor = St. Marks River | namedby = J. Finch, 1823 | region = Florida Panhandle | country = United States | coordinates = | unitof = None | subunits = None | underlies = | overlies = | thickness = | extent = Jefferson, Leon, and Wakulla counties | area = | map = | map_caption = ::figure[src="https://upload.wikimedia.org/wikipedia/commons/b/b6/St_Marks_Formation_map.png" caption="St. Marks Formation location in red."] ::
The St. Marks Formation is a Miocene geologic formation in the eastern Florida Panhandle.
Age
Epoch: Miocene ~23.03 to 5.33 mya, calculates to a period of
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.
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:
References
- Florida Carbonate "Formations" and Conflicting Interpretations of Injection Well Regulations
- Finch, J., Geological essay on the Tertiary formation in America: American Journal of Science, v. 7, p. 31-43, 1823.
References
- [https://sofia.usgs.gov/publications/maps/florida_geology/OFR80.pdf USGS Florida Geology, Open File Report 80]
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