| Ozan Formation | |
|---|---|
| Stratigraphic range: Cretaceous | |
 Fossil ammonites from the Ozan Formation | |
| Type | Formation |
| Sub-units | Austin Group |
| Underlies | Annona Chalk |
| Overlies | Austin Chalk, Brownstown Marl |
| Thickness | 150 to 250 feet [1] |
| Location | |
| Region | Arkansas, Oklahoma |
| Country | United States |
| Type section | |
| Named by | C.H. Dane [2] |
The Ozan Formation is a geologic formation in Arkansas, Oklahoma [1] and Texas. It preserves fossils dating back to the Cretaceous period.
The Cotter Formation is a geologic formation in Arkansas, Missouri, Oklahoma and in Virginia. It preserves fossils dating back to the Ordovician period.
The Batesville Sandstone is a geologic formation in northern Arkansas, United States, that dates to the Chesterian Series of the late Mississippian. The base of the Batesville Sandstone, named the Hindsville Limestone Member, unconformably lies on the Moorefield Formation.
The Hale Formation is a geologic formation in northern Arkansas that dates to the Morrowan Series of the early Pennsylvanian. The Hale Formation has two named members: the Cane Hill and the Prairie Grove Members. The lower member is the Cane Hill, a primarily sandstone and shale interval that unconformably overlies the Mississippian-age Pitkin Formation. The upper member, the Prairie Grove Member, is predominately limestone and conformably underlies the Bloyd Formation.
The Hindsville Formation, or Hindsville Limestone Member of the Batesville Formation, is a geologic unit in northern Arkansas and eastern Oklahoma that dates to the Chesterian Series of the late Mississippian. Named for the town of Hindsville in Madison County, Arkansas, this unit is recognized as a member of the Batesville Formation in Arkansas and a geologic formation in Oklahoma. Although, some workers have proposed raising the rank of this interval in Arkansas to formation status. Both the Batesville and Hindsville Formations overlie the Moorefield Formation and underlie the Fayetteville Shale.
The Moorefield Formation, or Moorefield Shale, is a geologic formation in northern Arkansas and eastern Oklahoma that dates to the Meramecian Series of the middle Mississippian. In Arkansas, this formation is generally recognized to have one member, the Ruddell Shale, in the upper Moorefield Formation.
The Bloyd Formation, or Bloyd Shale, is a geologic formation in Arkansas. It preserves fossils dating back to the Carboniferous period.
The Pitkin Formation, or Pitkin Limestone, is a fossiliferous geologic formation in northern Arkansas that dates to the Chesterian Series of the late Mississippian. This formation was first named the "Archimedes Limestone" by David Dale Owen in 1858, but was replaced in 1904. The Pitkin conformably overlies the Fayetteville Shale and unconformably underlies the Pennsylvanian-age Hale Formation. Some workers have considered the top of the Pitkin Formation to be a separate formation called the Imo Formation. However more recently, others have considered it as an informal member of the Pitkin Formation.
The Annona Chalk is a geologic formation in Arkansas, Texas, Louisiana, and Oklahoma. It preserves fossils dating back to the Cretaceous period. The formation is a hard, thick-bedded to massive, slightly fossiliferous chalk. It weathers white, but is blue-gray when freshly exposed. The unit is commercially mined for cement. Fossils in the Annona Chalk include coelenterates, echinoderms, annelids, bivalves, gastropods, cephalopods, and some vertebrate traces. The beds range in thickness, up to over 100 feet in depth in some areas ., but thins to the east and is only a few feet thick north of Columbus, Arkansas and is completely missing to the east. The break between the Annona Formation and the Ozan Formation appears to be sharp with a few tubular borings up to a foot long extending down from the Annona in to the Ozan.
The De Queen Formation, formerly known as the DeQueen Limestone Member is a Mesozoic geological formation located in southwestern Arkansas and southeastern Oklahoma in the United States. Fossil sauropod and theropod tracks have been reported from the formation. It preserves fossils dating back to the Cretaceous period, particularly the Albian age.
The Marlbrook Marl is a geologic formation in Arkansas. It preserves fossils dating back to the Cretaceous period.
The Saratoga Chalk is a geologic formation in Arkansas. It preserves fossils dating back to the Cretaceous period, specifically ammonites.
The Everton Formation is a geologic formation in northern Arkansas that dates to the middle Ordovician Period. Unconformities separate this formation from the underlying Powell Formation and the overlying St. Peter Sandstone Formation. Named for the town of Everton in Boone County, Arkansas in 1907, the Everton Formation is composed primarily of dolomite, limestone, and sandstone.
The Sharps Formation is a geologic formation in South Dakota. It preserves fossils dating back to the Paleogene.
The Winslow Formation was a geologic formation in Arkansas, now abandoned and replaced by the Atoka Formation, the Hartshorne Formation, and the lower McAlester Formation. It preserves fossils dating back to the Carboniferous period.
The Boggy Formation is a geologic formation in Arkansas and Oklahoma. It preserves fossils dating back to the Carboniferous period.
The Kiamichi Shale or Kiamichi Formation is a geologic formation in Arkansas and Texas. It preserves fossils dating back to the Cretaceous period.
The Johnson Spring Formation is a geologic formation in California. It preserves fossils dating back to the Ordovician period.
The Ocotillo Formation is a Pliocene fluvial-alluvial fan geologic formation in the Colorado Desert of Southern California.
The Cromer Knoll Group is a geological group of Early Cretaceous age, found at outcrop in eastern England and developed extensively beneath the North Sea in the UK, Norwegian and Danish sectors and in the Norwegian Sea. It preserves fossils dating back to the Early Cretaceous period.
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