Orange Island (Florida)
Encyclopedia
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.
running north to south. Edward J. Petuch states that Orange Island was a dominant geomorphological feature of the Bainbridge Subsea
on the Florida Platform
According to J. R. Bryan and the United States Geological Survey
, a lack of deposition with reference to the eastern side of the Ocala Platform indicates this area as Orange Island. The island also bounded the Okeechobean Sea
to its south.
~55.8—33.9 Ma., what was to become Florida (Florida Platform
) was a carbonate
bank with shallow sea covering it. During the Eocene, biological carbonates were deposited on this bank forming various layers. The Avon Park Formation
and Ocala Limestone
were formed at this time. Orange Island appears absent of Suwannee Limestone
due to either erosion or lack of deposition of material.(J. R. Bryan).
s rose almost as much as during the late Eocene. Parts of the platform remained above water creating Orange Island, a low relief island just 150 km (93.2 mi) south of the Oligocene Georgia coastline and Bainbridge Subsea with a shallow channel, the Gulf Trough
or Suwannee Strait, separating the two. The shallower Gulf Trough now supported a large coral reef
extending to the Salt Mountain Formation and Flint River Formation of southern Alabama
to Mitchell County, Georgia
. The western side of the island was bounded by the Pasco Reef System, an environment now only found in the southern Pacific Ocean
(Petuch).
During the middle Oligocene ~25 Ma, a world-wide cooling of the climate started the drying of the Dade Subsea, Gulf Trough, and in turn enlarging Orange Island. During the Chattian
of the Late Oligocene, land mammals
began their movement into what is now Florida with earliest of their fossils found in Hernando County
dating to 24.8 Ma. Also from that Chattian stage through early Aquitanian age
of the early Miocene, Orange Island expanded both northward and westward with carbonate lagoon
system on its west side. To the south of Orange Island, the Everglades Basin remained at 250 meters (850 feet) deep. Orange Island had its own rivers carrying sediments composed of sand and clay in to the Yeehaw Strait at Orange Island's southern tip.
Orange Island appears to have been a Pleistocene
animal and floral refugium
for central Florida
during the interglacial
periods of rising water and not unlike that of the river bank of the Apalachicola River
, the red hills near Marianna, Florida
, and coastal flatwoods
in the Florida panhandle.
Landmass
A landmass is a contiguous area of land surrounded by ocean. Although it may be most often written as one word to distinguish it from the usage "land mass"—the measure of land area—it is also used as two words.Landmasses include:*supercontinents...
of Florida dating from the middle 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—28.4 Ma. geologic stage
Geologic time scale
The geologic time scale provides a system of chronologic measurement relating stratigraphy to time that is used by geologists, paleontologists and other earth scientists to describe the timing and relationships between events that have occurred during the history of the Earth...
of the Early Oligocene epoch and named for Orange County, Florida
Orange County, Florida
Orange County is a county located in the U.S. state of Florida and is part of the Orlando-Kissimmee-Sanford Metropolitan Statistical Area . As of 2010 U.S. Census, the county had a population of 1,145,956....
, United States of America.
Location
Orange Island's general location is east of or on the eastern part of the Ocala PlatformOcala 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...
running north to south. Edward J. Petuch states that Orange Island was a dominant geomorphological feature of the Bainbridge Subsea
Choctaw Sea
The Choctaw Sea was a Cenozoic eutropical subsea, which along with the Okeechobean Sea, occupied the eastern Gulf of Mexico basin system bounding Florida.-Location:The Choctaw Sea was named for the Choctaw or Choctawhatchee River of northern Oligocene Florida...
on the Florida Platform
Florida Platform
The Florida Platform is a flat geological feature with the emergent portion being the Florida peninsula.-Structure:The platform forms a rampart between the Gulf of Mexico and the Atlantic Ocean. The platform's western edge, or Florida Escarpment, is normally defined with water depths at 300 feet...
According to J. R. Bryan and the United States Geological Survey
United States Geological Survey
The United States Geological Survey is a scientific agency of the United States government. The scientists of the USGS study the landscape of the United States, its natural resources, and the natural hazards that threaten it. The organization has four major science disciplines, concerning biology,...
, a lack of deposition with reference to the eastern side of the Ocala Platform indicates this area as Orange Island. The island also bounded 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...
to its south.
Origins
During the warm EoceneEocene
The Eocene Epoch, lasting from about 56 to 34 million years ago , is a major division of the geologic timescale and the second epoch of the Paleogene Period in the Cenozoic Era. The Eocene spans the time from the end of the Palaeocene Epoch to the beginning of the Oligocene Epoch. The start of the...
~55.8—33.9 Ma., what was to become Florida (Florida Platform
Florida Platform
The Florida Platform is a flat geological feature with the emergent portion being the Florida peninsula.-Structure:The platform forms a rampart between the Gulf of Mexico and the Atlantic Ocean. The platform's western edge, or Florida Escarpment, is normally defined with water depths at 300 feet...
) was a carbonate
Carbonate
In chemistry, a carbonate is a salt of carbonic acid, characterized by the presence of the carbonate ion, . The name may also mean an ester of carbonic acid, an organic compound containing the carbonate group C2....
bank with shallow sea covering it. During the Eocene, biological carbonates were deposited on this bank forming various layers. The Avon Park Formation
Avon Park Formation
The Avon Park Formation is a Middle Eocene geologic formation and is the oldest exposed sediments in Florida, United States.-Age:Period: PaleogeneEpoch: Middle Eocene~55.8 to 33.9 mya, calculates to a period of...
and 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...
were formed at this time. Orange Island appears absent of 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...
due to either erosion or lack of deposition of material.(J. R. Bryan).
Birth of Orange Island
By the Early Oligocene, sea levelSea level
Mean sea level is a measure of the average height of the ocean's surface ; used as a standard in reckoning land elevation...
s rose almost as much as during the late Eocene. Parts of the platform remained above water creating Orange Island, a low relief island just 150 km (93.2 mi) south of the Oligocene Georgia coastline and Bainbridge Subsea with a shallow channel, 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...
or Suwannee Strait, separating the two. The shallower Gulf Trough now supported a large coral reef
Coral reef
Coral reefs are underwater structures made from calcium carbonate secreted by corals. Coral reefs are colonies of tiny living animals found in marine waters that contain few nutrients. Most coral reefs are built from stony corals, which in turn consist of polyps that cluster in groups. The polyps...
extending to the Salt Mountain Formation and Flint River Formation of southern Alabama
Alabama
Alabama is a state located in the southeastern region of the United States. It is bordered by Tennessee to the north, Georgia to the east, Florida and the Gulf of Mexico to the south, and Mississippi to the west. Alabama ranks 30th in total land area and ranks second in the size of its inland...
to Mitchell County, Georgia
Mitchell County, Georgia
Mitchell County is a county located in the U.S. state of Georgia. It was created on December 21, 1857. As of 2000, the population was 23,932. The 2007 Census Estimate showed a population of 24,139. The county seat is Camilla.-Geography:...
. The western side of the island was bounded by the Pasco Reef System, an environment now only found in the southern Pacific Ocean
Pacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...
(Petuch).
During the middle Oligocene ~25 Ma, a world-wide cooling of the climate started the drying of the Dade Subsea, Gulf Trough, and in turn enlarging Orange Island. During the Chattian
Chattian
The 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...
of the Late Oligocene, land mammals
Mammal
Mammals are members of a class of air-breathing vertebrate animals characterised by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young...
began their movement into what is now Florida with earliest of their fossils found in Hernando County
Hernando County, Florida
Hernando County is a county located in the U.S. state of Florida. As of 2000, the population was 130,802. The U.S. Census Bureau 2006 estimate for the county is 165,409 . Its county seat is Brooksville, Florida. The majority of the county's population is in Spring Hill, west portion of Hernando...
dating to 24.8 Ma. Also from that Chattian stage through early Aquitanian age
Aquitanian age
The Aquitanian is, in the ICS' geologic timescale, the oldest age or lowest stage in the Miocene. It spans the time between 23.03 ± 0.05 Ma and 20.43 ± 0.05 Ma and is a dry, cooling period...
of the early Miocene, Orange Island expanded both northward and westward with carbonate lagoon
Lagoon
A lagoon is a body of shallow sea water or brackish water separated from the sea by some form of barrier. The EU's habitat directive defines lagoons as "expanses of shallow coastal salt water, of varying salinity or water volume, wholly or partially separated from the sea by sand banks or shingle,...
system on its west side. To the south of Orange Island, the Everglades Basin remained at 250 meters (850 feet) deep. Orange Island had its own rivers carrying sediments composed of sand and clay in to the Yeehaw Strait at Orange Island's southern tip.
Orange Island appears to have been a Pleistocene
Pleistocene
The 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 ....
animal and floral refugium
Refugium
Refugium may refer to:* Refugium , an appendage to a marine, brackish, or freshwater fish tank that shares the same water supply...
for central Florida
Central Florida
Central Florida is a regional designation for the area surrounding Orlando in east central Florida, United States. The area represents the third largest population concentration in Florida, after the South Florida and Tampa Bay regions, respectively....
during the interglacial
Interglacial
An Interglacial period is a geological interval of warmer global average temperature lasting thousands of years that separates consecutive glacial periods within an ice age...
periods of rising water and not unlike that of the river bank of the 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...
, the red hills near Marianna, Florida
Marianna, Florida
Marianna is a city in Jackson County, Florida, United States. The population was 6,230 at the 2000 census. As of 2004, the population estimated by the U.S. Census Bureau is 6,200 . It is the county seat of Jackson County and is home to Chipola College...
, and coastal flatwoods
Flatwoods
Flatwoods, Pineywoods, Longleaf Pine-Wiregrass Ecosystem refers to an ecological community in the Southeastern coastal plain of North America...
in the Florida panhandle.