| Hunton Megagroup | |
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| Stratigraphic range: Rhuddanian-Eifelian ~ | |
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| Named for | Hunton, Coal County, Oklahoma |
| Named by | Joseph A. Taff, 1902 [1] |
The Hunton Megagroup also Hunton Super Group, Hunton Group, Hunton Formation and Hunton Limestone is predominantly composed of carbonate rock, deposited between the Silurian and early to mid Devonian periods. In many States it acts as a reservoir for both hydrocarbons and water. [2]
The Clifty Limestone is a Middle Devonian geologic formation in the Ozark Plateaus of Arkansas. This thin formation can but up to 4 feet thick. [3] The name was introduced in 1916 by Albert Homer Purdue and Hugh Dinsmore Miser in their study of northern Arkansas. They designated a stratotype along the East Fork of Little Clifty Creek in Benton County, Arkansas. The Clifty Limestone is very sandy, light blue to bluish grey. [4]
The Penters Chert is a Devonian geologic formation in the Ozark Plateaus of Arkansas. Its thickness ranges up to 90'. [3] The name was introduced in 1921 by Hugh Dinsmore Miser in his study of Arkansas. [5] Miser designated a type locality near the old Penters Bluff railroad station in Izard County, Arkansas, however, he did not assign a stratotype. As of 2017, a reference section has not been designated for this unit.
The Bailey Limestone was first described by Ulrich, Buckley and Buehler, 1904, p. 110. It was named for the now abandoned town of Bailey's Landing near the village of Grand Eddy, on the Mississippi River. The formation is gray to greenish gray, silty with chert inclusions, thin-bedded, very hard limestone. [6]
The Lafferty Limestone is a Middle to Late Silurian geologic formation in the Ozark Plateaus of Arkansas. [5] The name was introduced in 1921 by Hugh Dinsmore Miser in his study of Arkansas, replacing part of the upper St. Clair Limestone. [3] Miser designated a type locality at Tate Spring, located 1.25 miles north of the site of the old Penters Bluff railroad station in Izard County, Arkansas, however, he did not assign a stratotype. As of 2017, a reference section has not been designated for this unit.
The Racine Formation or RacineDolomite is found from Wisconsin south through Illinois and Iowa. Its age is from 423 to 427 million years old. It contains fossils of many species of trilobites, brachiopods, crinoids, gastropods among others [8] This formation is found in Illinois, Iowa, Missouri and Wisconsin. The Racine is estimated to contain over 7 million barrels of oil in Illinois. [9]
The Moccasin Springs Formation is found in Missouri, Illinois and Kentucky. It is also recognized in Indiana. [10] This formation was first described by Becker (1974). The Moccasin Springs contains reef facies that are more common at its base. These are pure calcium carbonate (limestone). These reefs also make up the Terre Haute Bank on the eastern flank of the Illinois Basin. The top of the formation is mostly dark-gray to black dolomitic shale. This is occasionally interbedded very fine grained limestone, that is mostly dark-greenish-gray. Below is dense to fine grained limestone. It tends to be somewhat argillaceous. The colors range from pastel shades of pink, green, yellow, tan, and gray to saturated dark-gray and red to purple colors. These colors maybe mottled as well. [11]
The St. Clair Limestone is a geologic unit in Arkansas, and Oklahoma. It is classified as a Geologic Member in Indiana and Missouri. It dates back to the Middle of Silurian period. It is high density, high magnesium dolomitic limestone. [12] It was originally classified as a marble in Oklahoma due to the fact that it would hold a high polish, hence Marble City. It is sold in slabs and as tiles, in a similar manner as marble would be. [13] This unit has many economic uses in Arkansas and Oklahoma. It is used as a construction material, manufacture of quicklime, and manganese deposits are mined as well. [14] The St Clair is designated as a member of the Bainbridge Group in the State of Indiana. [15] In Illinois, Missouri, Arkansas and Oklahoma it is part of the Hunton Megagroup. The St. Clair is the Basal member of the Niagaran Series, making it part of the Tippecanoe sequence. Throughout most of the Southern extent the unit is roughly 10 to 20' thick. Moving northward it thickens to approximately 80 to 100' thick in the Illinois Basin. At its northernmost reaches where it grades in to the Joliet and Racine Formations it is about 150' thick.
The St. Clair is composed of course calcite grains to fine grains. It may contain partings of claystone or Mudstone. It can range in color from light-gray to chocolate brown, or even or purplish-black. Beds of pink crinoid remains are also found with in this unit, mostly toward the base.
The Sexton Creek Limestone is Silurian in age 443 - 441 Ma. [16] Named by (Savage, 1909, p. 518) revised by (Ulrich, 1911). It was named for Sexton Creek in Alexander County, Illinois. The Sexton Creek is composed of Limestone, Dolomite and Chert. In parts of the unit there maybe as much as 60% chert. In Indiana the Sexton Creek unconformably overlies Ordovician aged rock. Further west it overlies the Edgewood Formation. [17]
In exposures the following fossils have been found; Distacodus obliquicostatus, Pterospathodus amorphognathoides, Kockelella ranuliformis.
The Devonian Old Port Formation is a mapped bedrock unit in Pennsylvania, USA. Details of the type section and of stratigraphic nomenclature for this unit as used by the U.S. Geological Survey are available on-line at the National Geologic Map Database. Current nomenclature usage by U.S. Geological Survey restricts the name Old Port Formation to Pennsylvania, but correlative units are present in adjacent states.
The Big Clifty Formation is a geologic formation in Indiana. It preserves fossils dating back to the Carboniferous period.
The Waldron Shale is a geologic formation in Indiana. It preserves fossils dating back to the Silurian period. These fossils comprise at least three different benthic communities primarily living in the inter-reef, deep waters that were stable for much of the Wenlockian epoch. Many of these fossils are found most frequently around microbioherms constructed by small encrusting organisms which protected other species from the effects of storms.
The Kimmswick Limestone is an Ordovician geologic formation in Arkansas, Illinois and Missouri. Fossils occurring in the Kimmswick include corals, bryozoans, brachiopods, conodonts, trilobites, crinoids and mollusks.
The Fernvale Limestone is a geologic formation in Alabama, Arkansas, Illinois, Missouri, Oklahoma, and Tennessee. It preserves fossils dating back to the Ordovician period.
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 Vinini Formation is a marine, deep-water, sedimentary deposit of Ordovician to Early Silurian age in Nevada, U.S.A. It is notable for its highly varied, mainly siliceous composition, its mineral deposits, and controversies surrounding both its depositional environment and structural history. The formation was named by Merriam and Anderson for an occurrence along Vinini Creek in the Roberts Mountains of central Nevada and that name is now used extensively in the State.
The Womble Shale is a Middle Ordovician geologic formation in the Ouachita Mountains of Arkansas and Oklahoma. First described in 1892, this unit was not named until 1909 by Albert Homer Purdue in his study of the Ouachita Mountains of Arkansas, where he named this unit as part of the upper Ouachita Shale and the Stringtown Shale. In 1918, U.S. Geological Survey geologist, Hugh Dinsmore Miser, replaced Purdue's nomenclature with the Womble Shale. Miser assigned the town of Womble in Montgomery County, Arkansas as the type locality. As of 2017, a reference section for this unit has yet to be designated.
The Bigfork Chert is a Middle to Late Ordovician geologic formation in the Ouachita Mountains of Arkansas and Oklahoma. First described in 1892, this unit was not named until 1909 by Albert Homer Purdue in his study of the Ouachita Mountains of Arkansas. Purdue assigned the town of Big Fork in Montgomery County, Arkansas as the type locality, but did not designate a stratotype. As of 2017, a reference section for this unit has yet to be designated. The Bigfork Chert is known to produce planerite, turquoise, variscite, and wavellite minerals.
The Polk Creek Shale is a Late Ordovician geologic formation in the Ouachita Mountains of Arkansas and Oklahoma. First described in 1892, this unit was not named until 1909 by Albert Homer Purdue in his study of the Ouachita Mountains of Arkansas. Purdue assigned Polk Creek in Montgomery County, Arkansas as the type locality, but did not designate a stratotype. As of 2017, a reference section for this unit has yet to be designated.
The Blaylock Sandstone is a Silurian geologic formation in the Ouachita Mountains of Arkansas and Oklahoma. First described in 1892, this unit was not named until 1909 by Albert Homer Purdue in his study of the Ouachita Mountains of Arkansas. Purdue assigned the Blaylock Mountain in Montgomery County, Arkansas as the type locality, but did not designate a stratotype. As of 2017, a reference section for this unit has yet to be designated.
The Missouri Mountain Shale is a Silurian geologic formation in the Ouachita Mountains of Arkansas and Oklahoma in the United States. First described in 1892, this unit was not named until 1909 by Albert Homer Purdue in his study of the Ouachita Mountains of Arkansas. Purdue assigned the Missouri Mountains in Polk and Montgomery counties, Arkansas as the type locality, but did not designate a stratotype. As of 2017, a reference section for this unit has yet to be designated.
The Stanley Shale, or Stanley Group, is a Mississippian stratigraphic unit in the Ouachita Mountains of Arkansas and Oklahoma. First described in Arkansas in 1892, this unit was not named until 1902 by J.A. Taff in his study of the Ouachita Mountains of Oklahoma. Taff assigned the town of Stanley in Pushmataha County, Oklahoma as the type locality, but did not designate a stratotype. After introduction into Arkansas in 1909 by Albert Homer Purdue, the unit was redefined in 1918, when the formation known as the Fork Mountain Slate was abandoned and partially combined into the Stanley Shale. As of 2017, a reference section for the Stanley Shale has yet to be designated.
The Joachim Dolomite is a Middle Ordovician geologic formation in Arkansas, Illinois, and Missouri. The name was first introduced in 1894 by Arthur Winslow in his study of the geology of Missouri. Winslow designated a stratotype along Plattin Creek, which was misidentified as Joachim Creek, in Jefferson County. The name was introduced into Arkansas in 1911, replacing part of the, now abandoned, Izard Limestone.
The Plattin Limestone is a Middle Ordovician geologic formation in Arkansas, Illinois, and Missouri. The name was first introduced in 1904 by Edward Oscar Ulrich in his study of the geology of Missouri. A type locality was designated at the mouth of the Plattin Creek in Jefferson County, Missouri, however a stratotype was not assigned. As of 2017, a reference section has not been designated. The name was introduced into Arkansas in 1927, replacing part of the, now abandoned, Izard Limestone.
The Cason Shale is a Late Ordovician to Middle Silurian geologic formation in the Ozark Plateaus of Arkansas. The name was introduced in 1894 by Henry Shaler Williams in his study of Arkansas. Williams designated a type locality at what was known as the Cason tract and mine, near Batesville, Independence County, Arkansas, however, he did not assign a stratotype. As of 2017, a reference section has not been designated for this unit.
The Tokio Formation is a Late Cretaceous geologic formation in Arkansas and Oklahoma. Named in 1919 by Hugh Dinsmore Miser and Albert Homer Purdue in their study of Arkansas. They assigned the town of Tokio, Hempstead County, Arkansas as the type locality, but did not designate a stratotype for this unit.
Dudleyaspis is an extinct genus of Lower to Middle Devonian odontopleurid trilobites that lived in a shallow sea that lay between Euramerica and Gondwana. It was named in 1949 by Prantl & Pribyl.
The St. Clair Limestone is a geologic unit in Arkansas, and Oklahoma. It is classified as a Geologic Member in Indiana and Missouri. It dates back to the Middle of Silurian period. It is high density, high magnesium dolomitic limestone. It was originally classified as a marble in Oklahoma due to the fact that it would hold a high polish, hence Marble City. It is sold in slabs and as tiles, in a similar manner as marble would be. This unit has many economic uses in Arkansas and Oklahoma. It is used as a construction material, manufacture of quicklime, and manganese deposits are mined as well. The St Clair is designated as a member of the Bainbridge Group in the State of Indiana. In Illinois, Missouri, Arkansas and Oklahoma it is part of the Hunton Megagroup. The St. Clair is the Basal member of the Niagaran Series, making it part of the Tippecanoe sequence. Throughout most of the Southern extent the unit is roughly 10 to 20' thick. Moving northward it thickens to approximately 80 to 100' thick in the Illinois Basin. At its northernmost reaches where it grades in to the Joliet and Racine Formations it is about 150' thick.
The New Harmony Group is located in the State of Indiana. It is made up of three formations, the Grassy Knob Chert, the Backbone Limestone and Clear Creek Chert. It is Lower Devonian in age.
