| Alum Bluff Group | |
|---|---|
| Stratigraphic range: Neogene | |
| Type | Group |
| Location | |
| Region |  Georgia (U.S. state),  Florida,  Alabama |
| Country |  United States |
The Alum Bluff Group is a geologic group in the states of Georgia, Florida, and Alabama. It preserves fossils dating back to the Neogene period.
Period : Paleogene to Neogene
Epoch : Late Oligocene to Early Miocene
Faunal stage : Chattian through Hemphillian ~23.03–5.33 mya, calculates to a period of 17.7 million years
The Alum Bluff Group replaces the Hawthorn Group west of the Apalachicola River with occurrences in Bay, Calhoun, Holmes, Jackson, Liberty, Okaloosa, Walton, and Washington counties. It is younger than the Torreya Formation to the east based on superpositioning.
The Alum Bluff Group outcrops beneath a thin overburden in the western panhandle from river valleys in Okloosa County eastward to western Jackson County.
The group is composed of clays, sands and shell beds. These vary from fossil bearing sandy clays to sands, clays, and carbonate beds absent of fossil content with glauconite and phosphate mica which is common. The coloration is from cream to olive gray with mottled reddish brown in the weathered sections. The sands are soft and very fine to coarse with sporadic gravel while carbonate lenses are quite hard. Permeability of the sediments are generally low and are part of the intermediate confining unit/aquifer system. [1] [2]
The Alum Bluff Group are defined by the stratigraphic position and mollusks contained within. The group includes:
The Alum Bluff Group has a residuum on Miocene sediments and undifferentiated sediment of the Miocene. This consists of reddish brown, variably sandy clay with inclusions of variably fossiliferous, silicified limestone. The residuum includes Lower to Upper Miocene and younger weathered sediments. [3]
The Torreya Formation is a Miocene geologic formation with an outcrop in North Florida. It is within the Hawthorn Group.
The Coosawhatchie Formation is a Miocene geologic formation with an outcrop in North Florida. It is within the Hawthorn Group.
The Hawthorn Group is a stratigraphic unit that includes several geologic formations of Late Oligocene to Pliocene age in North Florida, United States. It is known for its phosphate rock resources, and for its rich assemblages of Neogene vertebrate fossils. It was originally called the Waldo Formation by L.C. Johnson of the United States Geological Survey in 1887, and later became the Hawthorne Group named for Hawthorne, Florida, where its phosphate-rich rock was quarried and processed for use as fertilizer.
The Arcadia Formation and its sub-unit, the Tampa Member, are Late Oligocene geologic formations in North Florida, United States. It is part of the Hawthorn Group.
The Chipola Formation is a Late Oligocene to Early Miocene geologic formation in the Florida Panhandle and member of the Alum Bluff Group.
The Peace River Formation is a Late Oligocene to Early Miocene geologic formation in the west-central Florida peninsula.
The Choctaw Sea was a Cenozoic eutropical subsea, which along with the Okeechobean Sea, occupied the eastern Gulf of Mexico basin system bounding Florida.
The Tamiami Formation is a Late Miocene to Pliocene geologic formation in the southwest Florida peninsula.
The Statenville Formation is a geological formation of northern Florida, USA.
The Chesapeake Group is a geologic group in Maryland, Virginia, Delaware, and North Carolina. It preserves mainly marine fossils dating back to the Miocene and Pliocene epochs of the Neogene period. This group contains one of the best studied fossil record of Neogene oceans in the world. Professional Paleontologists and amateur fossil hunters alike collect from this group intensely. The Calvert Cliffs stretch the length of Calvert County, Maryland and provide the best continuous stretch of the Calvert, Choptank, and St. Marys Formations. Ward (1985) recommended including the Old Church Formation in this group.
The Shoal River Formation is a geologic formation in Florida. The sandstones and marls of the formation preserve fossils dating back to the Serravallian epoch of the Middle Miocene of the Neogene period.
The Bone Valley Formation is a geologic formation in Florida. It is sometimes classified as the upper member of the Peace River Formation of the Hawthorn Group. It contains economically important phosphorite deposits that are mined in west-central Florida, as well as rich assemblages of vertebrate fossils.
The Prairie Bluff Chalk is a geologic formation in Alabama and Mississippi. It preserves fossils dating back to the Cretaceous period.
The Popotosa Formation is a geologic formation in New Mexico. It preserves fossils dating back to the Neogene period. These include the Socorro flora, notable for its fine preservation of plant reproductive structures.
The Kern River Beds Formation is a Neogene Period geologic formation in the southeastern San Joaquin Valley, within Kern County, California.
The Chanac Formation is a Cenozoic Era sandstone geologic formation in the southeastern San Joaquin Valley, within Kern County, California.
The Baitoa Formation is a geologic formation in Dominican Republic. The formation consists of siltstones and limestones deposited in a shallow marine to reef environment. The formation, unconformably overlying the Tabera Formation and unconformably overlain by the Cercado Formation, preserves bivalve, gastropod, echinoid and coral fossils dating back to the Burdigalian to Langhian period.
The August Town Formation is a geologic formation in Jamaica. It preserves fossils dating back to the Neogene period.
