Choctaw Sea
Encyclopedia
The Choctaw Sea was a Cenozoic
eutropical subsea
, which along with the Okeechobean Sea
, occupied the eastern Gulf of Mexico
basin system bounding Florida.
of northern Oligocene
Florida
. It occupied most of the Florida Panhandle
including the river deltas of the Choctawhatchee River
, Apalachicola River
, and Ochlockonee River
. At its maximum coverage it encompassed an area as far north as the city of Bainbridge
in Southwest Georgia
and as far to the southeast as Taylor County, Florida
, United States
.
The Choctaw Sea was divided further in to two groups of three subsea
s based upon marine fauna. These subseas were named:
The Bainbridge Subsea was named for the fossil beds of Bainbridge, Georgia
and is the oldest subsea. This period spanned the existence of the Gulf Trough
between Georgia and Florida's Orange Island
. It was a warm but cooling climate, moving towards an ice age. The Suwannee Limestone
was established during this time. Basilosaurus cetoides
and Zygorhiza
, early toothed whales, as well as Protosiren
, an extinct ancestor of the Manatee
, inhabit these waters and are the earliest mammal fossils uncovered with specimens from Citrus County
in dolomite
~40—37 Ma. and Marion County, Florida
dating from 37.2—33.9 Ma.
The Chattahoochee Subsea was named for the Chattahoochee Formation which formed during the rise in sea level. The Chattahoochie Subsea was much smaller in size than the Bainbridge and during the filling of the Chattahoochee, the St. Marks Formation
of limestone and sand was established. The Gulf Trough closed between Georgia and Florida forming the complete Florida peninsula
allowing land animals to move southward. The fossil record shows that land animals entered the newly formed peninsula ~24.8 Ma.
The Chipola Subsea was named after the Chipola Formation
and was formerly known as the Chipola Sea. It was created by rising sea level flooding the area once again. The Torreya Formation
, a geologic formation extending from Gadsden
to Hamilton Couny
was established during this period. A somewhat narrow land bridge exists with a width from Madison County
to Duval County, Florida
extending in to Georgia. The Middle Miocene Disruption
, an extinction of many mammal genera
begins.
A very short dry period follows the Chipola lasting possibly 1 million years. During the time the Middle Miocene Disruption continues. Forests slowly draw in massive amounts of carbon dioxide
, gradually lowering the level of atmospheric CO2 from 650 ppmv down to around 100 ppmv.
The Walton Subsea was named for the fossil beds of Walton County
.
The Alaqua Subsea was named for the fossil beds found along Alaqua Creek, Walton County. The period of time after the Alaqua experienced a somewhat long dry period. A major event was the Messinian salinity crisis
or dry Mediterranean. It was replenished with the Zanclean flood
which raised the world-wide sea level 10 meters or 33 feet.
The Jackson Subsea was named after the Jackson Bluff Formation and formerly called the "Jackson Sea." It was created during the rise in sea level during the Pliocene
. During this period the last glacial period known as the Wisconsin ice age begins.
Cenozoic
The Cenozoic era is the current and most recent of the three Phanerozoic geological eras and covers the period from 65.5 mya to the present. The era began in the wake of the Cretaceous–Tertiary extinction event at the end of the Cretaceous that saw the demise of the last non-avian dinosaurs and...
eutropical subsea
Eutropical subsea
A Eutropical subsea is a low-latitude, circumequatorial body of water within a eutropical, that is genuinely tropical rather than sub-tropical ecozone. It is applied to marine waters considered truly tropical, in which the temperature does not drop below 20 degrees Celsius...
, which along with the Okeechobean Sea
Okeechobean Sea
The Okeechobean Sea was a Cenozoic eutropical subsea, which along with the Choctaw Sea, occupied the eastern Gulf of Mexico basin system bounding Florida.-Location:The Okeechobean Sea was a named for Lake Okeechobee of southern Early Oligocene Florida...
, occupied the eastern Gulf of Mexico
Gulf of Mexico
The Gulf of Mexico is a partially landlocked ocean basin largely surrounded by the North American continent and the island of Cuba. It is bounded on the northeast, north and northwest by the Gulf Coast of the United States, on the southwest and south by Mexico, and on the southeast by Cuba. In...
basin system bounding Florida.
Location
The Choctaw Sea was named for the Choctaw or Choctawhatchee RiverChoctawhatchee River
The Choctawhatchee River is a river in the southern United States, flowing through southeast Alabama and the Panhandle of Florida before emptying into Choctawhatchee Bay in Okaloosa and Walton counties...
of northern Oligocene
Oligocene
The Oligocene is a geologic epoch of the Paleogene Period and extends from about 34 million to 23 million years before the present . As with other older geologic periods, the rock beds that define the period are well identified but the exact dates of the start and end of the period are slightly...
Florida
Florida
Florida is a state in the southeastern United States, located on the nation's Atlantic and Gulf coasts. It is bordered to the west by the Gulf of Mexico, to the north by Alabama and Georgia and to the east by the Atlantic Ocean. With a population of 18,801,310 as measured by the 2010 census, it...
. It occupied most of the Florida Panhandle
Florida Panhandle
The Florida Panhandle, an informal, unofficial term for the northwestern part of Florida, is a strip of land roughly 200 miles long and 50 to 100 miles wide , lying between Alabama on the north and the west, Georgia also on the north, and the Gulf of Mexico to the south. Its eastern boundary is...
including the river deltas of the Choctawhatchee River
Choctawhatchee River
The Choctawhatchee River is a river in the southern United States, flowing through southeast Alabama and the Panhandle of Florida before emptying into Choctawhatchee Bay in Okaloosa and Walton counties...
, Apalachicola River
Apalachicola River
The Apalachicola River is a river, approximately 112 mi long in the State of Florida. This river's large watershed, known as the ACF River Basin for short, drains an area of approximately into the Gulf of Mexico. The distance to its farthest headstream in northeast Georgia is approximately 500...
, and Ochlockonee River
Ochlockonee River
The Ochlockonee River is a fast running river originating in Georgia and flowing for before terminating in Florida.- Background :The Ochlockonee originates south of the town of Sylvester in Worth County in southwest Georgia emptying into Ochlockonee Bay, then into Apalachee Bay, in Florida...
. At its maximum coverage it encompassed an area as far north as the city of Bainbridge
Bainbridge, Georgia
As of the census of 2000, there were 11,722 people, 4,444 households, and 3,013 families residing in the city. The population density was 255.6/km² . There were 5,051 housing units at an average density of 285.2 per square mile...
in Southwest Georgia
Southwest Georgia
Southwest Georgia is a thirteen-county region in the U.S. state of Georgia. A common acronym used is SOWEGA.The largest city is Albany. Counties include Baker, Calhoun, Colquitt, Decatur, Dougherty, Early, Grady, Lee, Miller, Mitchell, Seminole, Terrell, Thomas, and Worth.In 1995, 25% of the...
and as far to the southeast as Taylor County, Florida
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...
, United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
.
The Choctaw Sea was divided further in to two groups of three subsea
Subsea
Subsea is a general term frequently used to refer to equipment, technology, and methods employed in marine biology, undersea geology, offshore oil and gas developments, underwater mining, and offshore wind power industries.- Oil and gas :...
s based upon marine fauna. These subseas were named:
- Bainbridge Subsea
- Chattahoochie Subsea
- Chipola Subsea
- Walton Subsea
- Alaqua Subsea
- Jackson Subsea
Bainbridge Subsea
- PeriodSeries (stratigraphy)Series are subdivisions of rock layers made based on the age of the rock and corresponding to the dating system unit called an epoch, both being formally defined international conventions of the geological timescale. A series is therefore a sequence of rock depositions defining a...
: OligoceneOligoceneThe Oligocene is a geologic epoch of the Paleogene Period and extends from about 34 million to 23 million years before the present . As with other older geologic periods, the rock beds that define the period are well identified but the exact dates of the start and end of the period are slightly...
. - Geologic stage: RupelianRupelianThe 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....
through early ChattianChattianThe Chattian is, in the geologic timescale, the youngest of two ages or upper of two stages of the Oligocene epoch/series. It spans the time between and . The Chattian is preceded by the Rupelian and is followed by the Aquitanian .-Stratigraphic definition:The Chattian was introduced by Austrian...
. ~33.9—28.4 Ma (beginning approximately ). - Animal age: OrellanOrellanThe Orellan North American Stage on the geologic timescale is the North American faunal stage according to the North American Land Mammal Ages chronology , typically set from 33,900,000 to 33,300,000 years BP, a period of . It is usually considered to fall within the Early Oligocene...
through GeringianGeringianThe Geringian North American Stage on the geologic timescale is the North American faunal stage according to the North American Land Mammal Ages chronology , typically set from 30,800,000 to 26,300,000 years BP, a period of . It is usually considered to fall within the Oligocene epoch...
. ~33.9—26.3 Ma. - Post-Bainbridge dry period: Chattian ~28.4—23.03 Ma.
The Bainbridge Subsea was named for the fossil beds of Bainbridge, Georgia
Bainbridge, Georgia
As of the census of 2000, there were 11,722 people, 4,444 households, and 3,013 families residing in the city. The population density was 255.6/km² . There were 5,051 housing units at an average density of 285.2 per square mile...
and is the oldest subsea. This period spanned the existence of the Gulf Trough
Gulf Trough
The Gulf Trough, also known as the Suwanee Straits, is an ancient geologic feature of Florida present during the Paleogene...
between Georgia and Florida's 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:...
. It was a warm but cooling climate, moving towards an ice age. The Suwannee Limestone
Suwannee Limestone
The Suwanee Limestone is an Early Oligocene geologic formation of exposed limestones in North Florida, United States.-Age:Period: PaleogeneEpoch: Early Oligocene...
was established during this time. Basilosaurus cetoides
Basilosaurus
Basilosaurus is a genus of cetacean that lived from in the Late Eocene. Its fossilized remains were first discovered in the southern United States . The American fossils were initially believed to be some sort of reptile, hence the suffix -"saurus", but later found to be a marine mammal...
and Zygorhiza
Zygorhiza
Zygorhiza kochii is an extinct species of cetacean.Zygorhiza was a smaller, less elongated, 6 m long relative of the famous Basilosaurus. Its bodily proportions were similar to those of modern whales, although, unlike modern species, it had a distinct neck, and flippers which could be moved at...
, early toothed whales, as well as Protosiren
Protosiren
Protosiren is an extinct early genus of the order Sirenia. Protosiren existed throughout the Lutetian and Bartonian stages of the Middle Eocene. Its geographic distribution was intercontinental: fossils have been found in the United States , Egypt, France, Hungary, India, and Pakistan...
, an extinct ancestor of the Manatee
Manatee
Manatees are large, fully aquatic, mostly herbivorous marine mammals sometimes known as sea cows...
, inhabit these waters and are the earliest mammal fossils uncovered with specimens from Citrus County
Citrus County, Florida
Citrus County is a county located in the U.S. state of Florida. As of 2000, the population was 118,085. The U.S. Census Bureau 2008 estimate for the county was 141,416 . Its county seat is Inverness, Florida...
in dolomite
Dolomite
Dolomite is a carbonate mineral composed of calcium magnesium carbonate CaMg2. The term is also used to describe the sedimentary carbonate rock dolostone....
~40—37 Ma. and Marion County, Florida
Marion County, Florida
Marion County is a county located in the U.S. state of Florida. The U.S. Census Bureau 2006 estimate for the county is 316,183. Its county seat is Ocala....
dating from 37.2—33.9 Ma.
Chattahoochee Subsea
- Period: MioceneMioceneThe Miocene is a geological epoch of the Neogene Period and extends from about . The Miocene was named by Sir Charles Lyell. Its name comes from the Greek words and and means "less recent" because it has 18% fewer modern sea invertebrates than the Pliocene. The Miocene follows the Oligocene...
. - Geologic stage: Late ChattianChattianThe Chattian is, in the geologic timescale, the youngest of two ages or upper of two stages of the Oligocene epoch/series. It spans the time between and . The Chattian is preceded by the Rupelian and is followed by the Aquitanian .-Stratigraphic definition:The Chattian was introduced by Austrian...
through early Aquitanian ~28.4—23.03 Ma., approximately . - Animal age: ArikareeanArikareeanThe Arikareean North American Stage on the geologic timescale is the North American faunal stage according to the North American Land Mammal Ages chronology , typically set from 30,600,000 to 20,800,000 years BP, a period of . It is usually considered to overlap the Oligocene and Miocene epochs...
. ~30.8—20.6 Ma. - Post-Chattahoochee dry period: Late Aquitanian through early Burdigian ~23.0—20.5 Ma.
The Chattahoochee Subsea was named for the Chattahoochee Formation which formed during the rise in sea level. The Chattahoochie Subsea was much smaller in size than the Bainbridge and during the filling of the Chattahoochee, the St. Marks Formation
St. Marks Formation
The St. Marks Formation is a Miocene geologic formation in the eastern Florida Panhandle.-Age:Period: NeogeneEpoch: Miocene ~23.03 to 5.33 mya, calculates to a period of Faunal stage: Arikareean through Hemphillian-Location:The St...
of limestone and sand was established. The Gulf Trough closed between Georgia and Florida forming the complete Florida peninsula
Peninsula
A peninsula is a piece of land that is bordered by water on three sides but connected to mainland. In many Germanic and Celtic languages and also in Baltic, Slavic and Hungarian, peninsulas are called "half-islands"....
allowing land animals to move southward. The fossil record shows that land animals entered the newly formed peninsula ~24.8 Ma.
Chipola Subsea
- Period: Miocene.
- Stage: Early BurdigalianBurdigalianThe Burdigalian is, in the geologic timescale, an age or stage in the early Miocene. It spans the time between 20.43 ± 0.05 Ma and 15.97 ± 0.05 Ma...
through the late LanghianLanghianThe Langhian is, in the ICS geologic timescale, an age or stage in the middle Miocene epoch/series. It spans the time between 15.97 ± 0.05 Ma and 13.65 ± 0.05 Ma . The Langhian was a continuing warming period defined by Lorenzo Pareto in 1864, it was originally established in the Langhe area north...
~20.43—15.97 Ma., approximately . - Animal age: Hemingfordian through BarstovianBarstovianThe Barstovian North American Stage on the geologic timescale is the North American faunal stage according to the North American Land Mammal Ages chronology , typically set from 16,300,000 to 13,600,000 years BP, a period of . It is usually considered to overlap the Langhian and Serravallian...
~20.3—13.6 Ma. - Post-Chipola dry period: Early SerravallianSerravallianThe Serravallian is in the geologic timescale an age or a stage in the middle Miocene epoch/series, that spans the time between 13.65 ± 0.05 Ma and 11.608 ± 0.005 Ma...
~13.65—12.0 Ma.
The Chipola Subsea was named after the Chipola Formation
Chipola Formation
The Chipola Formation is a Late Oligocene to Early Miocene geologic formation in the Florida Panhandle and member of the Alum Bluff Group.-Age:Period: NeogeneEpoch: Early Miocene to Middle Miocene...
and was formerly known as the Chipola Sea. It was created by rising sea level flooding the area once again. The Torreya Formation
Torreya Formation
The Torreya Formation is a Miocene geologic formation with an outcrop in North Florida. It is within the Hawthorn Group.-Age:Period: NeogeneEpoch: Early Miocene...
, a geologic formation extending from Gadsden
Gadsden County, Florida
Gadsden County is a county located in the panhandle of the U.S. state of Florida. As of the 2000 census, the population was 45,087. The U.S. Census Bureau 2005 estimate for the county is 46,428 . Its county seat is Quincy, Florida. Gadsden County is the only predominantly African-American...
to Hamilton Couny
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 :...
was established during this period. A somewhat narrow land bridge exists with a width from Madison County
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....
to Duval County, Florida
Duval County, Florida
Duval County is a county located in the U.S. state of Florida. As of 2010, the population was 864,263. Its county seat is Jacksonville, with which the Duval County government has been consolidated since 1968...
extending in to Georgia. The Middle Miocene Disruption
Middle Miocene disruption
The term Middle Miocene disruption, alternatively the Middle Miocene extinction or Middle Miocene extinction peak, refers to a wave of extinctions of terrestrial and aquatic life forms that occurred around the middle of the Miocene Epoch, c...
, an extinction of many mammal genera
Genera
Genera is a commercial operating system and development environment for Lisp machines developed by Symbolics. It is essentially a fork of an earlier operating system originating on the MIT AI Lab's Lisp machines which Symbolics had used in common with LMI and Texas Instruments...
begins.
A very short dry period follows the Chipola lasting possibly 1 million years. During the time the Middle Miocene Disruption continues. Forests slowly draw in massive amounts of carbon dioxide
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...
, gradually lowering the level of atmospheric CO2 from 650 ppmv down to around 100 ppmv.
Walton Subsea
- Period: Miocene.
- Geologic stage: Early Serravallian through early TortonianTortonianThe Tortonian is in the geologic timescale an age or stage of the late Miocene that spans the time between 11.608 ± 0.005 Ma and 7.246 ± 0.005 Ma . It follows the Serravallian and is followed by the Messinian....
~12.00—7.2 Ma., approximately . - Animal age: ClarendonianClarendonianThe Clarendonian North American Stage on the geologic timescale is the North American faunal stage according to the North American Land Mammal Ages chronology , typically set from 13,600,000 to 10,300,000 years BP, a period of . It is usually considered to overlap the Serravallian of the Middle...
~13.6—10.3 Ma through HemphillianHemphillianThe Hemphillian North American Stage on the geologic timescale is the North American faunal stage according to the North American Land Mammal Ages chronology , typically set from 10,300,000 to 4,900,000 years BP, a period of . It is usually considered to overlap the Tortonian epoch of the Late...
~10.3—4.9 Ma. - Post-Walton dry period: Early Tortonian ~10.0—9.0 Ma.
The Walton Subsea was named for the fossil beds of Walton County
Walton County, Florida
Walton County is a county located in the state of Florida. As of 2000, the population was 40,601. The U.S. Census Bureau 2005 estimate for the county is 50,324. Its county seat is DeFuniak Springs, Florida. The county is home to the highest natural point in Florida: Britton Hill, at .- History...
.
Alaqua Subsea
- Period: Miocene.
- Geologic time period: Mid Tortonian through mid MessinianMessinianThe Messinian is in the geologic timescale the last age or uppermost stage of the Miocene. It spans the time between 7.246 ± 0.005 Ma and 5.332 ± 0.005 Ma...
~7.246—5.332 Ma., approximately . - Animal age: HemphillianHemphillianThe Hemphillian North American Stage on the geologic timescale is the North American faunal stage according to the North American Land Mammal Ages chronology , typically set from 10,300,000 to 4,900,000 years BP, a period of . It is usually considered to overlap the Tortonian epoch of the Late...
~10.3—4.9 Ma.
- Post-Alaqua dry period: The late Messinian through ZancleanZancleanThe Zanclean is the lowest stage or earliest age on the geologic time scale of the Pliocene. It spans the time between 5.332 and 3.6 Ma ± 0.005 Ma . It is preceded by the Messinian age of the Miocene epoch, and followed by the Piacenzian age....
~5.332—3.6 Ma.
The Alaqua Subsea was named for the fossil beds found along Alaqua Creek, Walton County. The period of time after the Alaqua experienced a somewhat long dry period. A major event was the Messinian salinity crisis
Messinian salinity crisis
The Messinian Salinity Crisis, also referred to as the Messinian Event, and in its latest stage as the Lago Mare event, was a geological event during which the Mediterranean Sea went into a cycle of partly or nearly complete desiccation throughout the latter part of the Messinian age of the Miocene...
or dry Mediterranean. It was replenished with the Zanclean flood
Zanclean flood
The Zanclean flood is a flood theorized to have refilled the Mediterranean Sea 5.33 million years ago, at the beginning of the Zanclean age, between the Miocene and Pliocene, which ended the Messinian salinity crisis...
which raised the world-wide sea level 10 meters or 33 feet.
Jackson Subsea
- Period: PliocenePlioceneThe Pliocene Epoch is the period in the geologic timescale that extends from 5.332 million to 2.588 million years before present. It is the second and youngest epoch of the Neogene Period in the Cenozoic Era. The Pliocene follows the Miocene Epoch and is followed by the Pleistocene Epoch...
through PleistocenePleistoceneThe Pleistocene is the epoch from 2,588,000 to 11,700 years BP that spans the world's recent period of repeated glaciations. The name pleistocene is derived from the Greek and ....
. - Geologic time period: PiacenzianPiacenzianThe Piacenzian is in the international geologic timescale the upper stage or latest age of the Pliocene. It spans the time between 3.6 ± 0.005 Ma and 2.588 ± 0.005 Ma...
through BlancanBlancanThe Blancan North American Stage on the geologic timescale is the North American faunal stage according to the North American Land Mammal Ages chronology , typically set from 4,750,000 to 1,808,000 years BP, a period of .. It is usually considered to start in the early-mid Pliocene epoch and end...
~3.600—2.588 Ma., approximately . - Animal age: BlancanBlancanThe Blancan North American Stage on the geologic timescale is the North American faunal stage according to the North American Land Mammal Ages chronology , typically set from 4,750,000 to 1,808,000 years BP, a period of .. It is usually considered to start in the early-mid Pliocene epoch and end...
~4.9—1.8 Ma. - Post-Jackson dry period: Piacenzian through Halocene ~2.588 Ma. —present. The Northern HemisphereNorthern HemisphereThe Northern Hemisphere is the half of a planet that is north of its equator—the word hemisphere literally means “half sphere”. It is also that half of the celestial sphere north of the celestial equator...
is in a full ice age with its final retreat around 11,000 years ago.
The Jackson Subsea was named after the Jackson Bluff Formation and formerly called the "Jackson Sea." It was created during the rise in sea level during the Pliocene
Pliocene
The Pliocene Epoch is the period in the geologic timescale that extends from 5.332 million to 2.588 million years before present. It is the second and youngest epoch of the Neogene Period in the Cenozoic Era. The Pliocene follows the Miocene Epoch and is followed by the Pleistocene Epoch...
. During this period the last glacial period known as the Wisconsin ice age begins.