The Suwanee Limestone is an Early Oligocene geologic formation

Geologic formation

A formation or geological formation is the fundamental unit of lithostratigraphy. A formation consists of a certain number of rock strata that have a comparable lithology, facies or other similar properties...

 of exposed limestone

Limestone

Limestone is a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate . Many limestones are composed from skeletal fragments of marine organisms such as coral or foraminifera....

s in North Florida

North Florida

North Florida refers to the northernmost part of the U.S. state of Florida, including some counties that border the state of Georgia. It also borders the Big Bend with Madison County and Taylor County to the east and the Central Florida region to its south....

, United States

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

.

Age

Period: Paleogene

Paleogene

The Paleogene is a geologic period and system that began 65.5 ± 0.3 and ended 23.03 ± 0.05 million years ago and comprises the first part of the Cenozoic Era...

Epoch

Epoch (geology)

An epoch is a subdivision of the geologic timescale based on rock layering. In order, the higher subdivisions are periods, eras and eons. We are currently living in the Holocene epoch...

: Early Oligocene

Faunal stage

Faunal stage

In chronostratigraphy, a stage is a succession of rock strata laid down in a single age on the geologic timescale, which usually represents millions of years of deposition. A given stage of rock and the corresponding age of time will by convention have the same name, and the same boundaries.Rock...

: Rupelian

Rupelian

The Rupelian is, in the geologic timescale, the older of two ages or the lower of two stages of the Oligocene epoch/series. It spans the time between and . It is preceded by the Priabonian stage and is followed by the Chattian stage....

 ~33.9 to ~23 mya, calculates to a period of approximately

Location

Suwannee Limestone is found in the peninsula carbonate outcroppings on the northwestern, northeastern and southwestern flanks of the Ocala Platform

Ocala Platform

The Ocala Platform or Ocala Uplift is a geologic formation, a structural high, and a northwest-trending uplift paralleling the Peninsular Arch along the west coast.-Age:Period: NeogeneEpoch: Early Late Oligocene through Pliocene...

. However, Suwannee Limestone is not present on an area known as Orange Island

Orange Island (Florida)

Orange Island is the earliest emergent landmass of Florida dating from the middle Rupelian ~33.9—28.4 Ma. geologic stage of the Early Oligocene epoch and named for Orange County, Florida, United States of America.-Location:...

 on the eastern side of the Ocala Platform

Ocala Platform

The Ocala Platform or Ocala Uplift is a geologic formation, a structural high, and a northwest-trending uplift paralleling the Peninsular Arch along the west coast.-Age:Period: NeogeneEpoch: Early Late Oligocene through Pliocene...

 due to erosion, nondeposition or both. This limestone is present in southeastern Leon

Leon County, Florida

Leon County is a county located in the state of Florida, named after the Spanish explorer Juan Ponce de León. At the 2010 Census, the population was 275,487. The county seat of Leon County is Tallahassee which also serves as the state capital. The county seat is home to two of Florida's major...

, Jefferson

Jefferson County, Florida

Jefferson County is a county located in the U.S. state of Florida. As of 2000, the population is 12,902. The U.S. Census Bureau 2005 estimate for the county is 14,490 . Its county seat is Monticello, Florida....

, Madison

Madison County, Florida

Madison County is a county located in the state of Florida. As of 2000, the population was 18,733. The U.S. Census Bureau 2005 estimate for the county is 19,902. Its county seat is Madison, Florida. Madison County is one of Florida's five dry counties....

, Taylor

Taylor County, Florida

Taylor County is a county located in the state of Florida. As of 2000, the population was 19,256. The U.S. Census Bureau 2005 estimate for the county was 19,622 . Its county seat is Perry, Florida.- History :Taylor County was created in 1856...

, Lafayette

Lafayette County, Florida

Lafayette County is a county located in the state of Florida. As of 2000, the population was 7,022. It is the second least populated county in the state, having one more resident, according to the 2000 census, than Liberty County, Florida. The U.S. Census Bureau 2005 estimate for the county is...

 counties as well as Hamilton

Hamilton County, Florida

Hamilton County is a county located in the U.S. state of Florida. As of 2000, the population was 13,327. The U.S. Census Bureau 2005 estimate for the county is 13,983 . Its county seat is Jasper, Florida.- History :...

 along the upper Suwannee River

Suwannee River

The Suwannee River is a major river of southern Georgia and northern Florida in the United States. It is a wild blackwater river, about long. The Suwannee River is the site of the prehistoric Suwannee Straits which separated peninsular Florida from the panhandle.-Geography:The river rises in the...

 basin, and southward into Suwannee County, Florida

Suwannee County, Florida

Suwannee County is a county located in the state of Florida. As of 2000, the population was 34,844. The U.S. Census Bureau 2005 estimate for the county was 38,624 . Its county seat is Live Oak, Florida. Suwannee County was a dry county until August, 2011.....

.

Early Oligocene Suwanee Limestone was recognized in the northwestern peninsula by P. F. Huddleston in 1993 as a triple subdivision of Suwanee Limestone, Ellaville Limestone, and Suwannacoochee Dolostone.

Composition

Suwanee Limestone consists of a white to cream, poorly to well hardened, fossil rich, vuggy to moldic grainstone

Grainstone

Under the Dunham classification, grainstones are grain-supported carbonate sedimentary rocks that contain no micrite. The spaces between grains are filled with sparry cement.-References:...

 and packstone. The dolomitized parts of the Suwannee Limestone are gray, tan, light brown to moderate brown, moderately to well indurated (hard), finely to coarsely crystalline, dolostone

Dolostone

Dolostone or dolomite rock is a sedimentary carbonate rock that contains a high percentage of the mineral dolomite. In old U.S.G.S. publications it was referred to as magnesian limestone. Most dolostone formed as a magnesium replacement of limestone or lime mud prior to lithification. It is...

 with limited occurrences of fossil bearing beds. Limestone in silicate

Silicate

A silicate is a compound containing a silicon bearing anion. The great majority of silicates are oxides, but hexafluorosilicate and other anions are also included. This article focuses mainly on the Si-O anions. Silicates comprise the majority of the earth's crust, as well as the other...

 form is common in Suwannee Limestone.

Overlay

The Suwanee Limestone overlies the Ocala Limestone

Ocala Limestone

The Ocala Limestone is a late Eocene geologic formation of exposed limestones near Ocala, Marion County, Florida.-Age:Period: PaleogeneEpoch: Late EoceneFaunal stage: Late Clarkforkian through early Orellan...

and forms part of the intermediate confining unit/aquifer system. (USGS)