Dunkard Group
Encyclopedia
The Permian
Dunkard Group (Pd) is an area of rock, Early Permian in age, in the south of Ohio
, southwestern Pennsylvania
, West Virginia
and the hilltops of the Georges Creek
Basin of Maryland
. It is found primarily in Washington County
. It is notable for being one of the few areas of Permian sediment east of the Mississippi River
. In addition, it is the youngest surface rock in the state of Ohio.
It consists of Red and green shale
, siltstone
, and sandstone
, with thin lenticular beds of argillaceous limestone
and thin beds of impure coal
The base of the layer contains thick-bedded, white conglomeratic
sandstone. The layer's thickness is greater than 200 feet in Maryland.
The fossils found in the Dunkard Group are similar to ones found in Texas
and Oklahoma
of similar age.
Permian
The PermianThe term "Permian" was introduced into geology in 1841 by Sir Sir R. I. Murchison, president of the Geological Society of London, who identified typical strata in extensive Russian explorations undertaken with Edouard de Verneuil; Murchison asserted in 1841 that he named his "Permian...
Dunkard Group (Pd) is an area of rock, Early Permian in age, in the south of Ohio
Ohio
Ohio is a Midwestern state in the United States. The 34th largest state by area in the U.S.,it is the 7th‑most populous with over 11.5 million residents, containing several major American cities and seven metropolitan areas with populations of 500,000 or more.The state's capital is Columbus...
, southwestern Pennsylvania
Pennsylvania
The Commonwealth of Pennsylvania is a U.S. state that is located in the Northeastern and Mid-Atlantic regions of the United States. The state borders Delaware and Maryland to the south, West Virginia to the southwest, Ohio to the west, New York and Ontario, Canada, to the north, and New Jersey to...
, West Virginia
West Virginia
West Virginia is a state in the Appalachian and Southeastern regions of the United States, bordered by Virginia to the southeast, Kentucky to the southwest, Ohio to the northwest, Pennsylvania to the northeast and Maryland to the east...
and the hilltops of the Georges Creek
Georges Creek
Georges Creek is a tributary stream of the North Branch Potomac River in western Maryland. The creek has its headwaters near Frostburg and empties into the North Branch Potomac River at Westernport, all in western Allegany County. Along the Georges Creek Valley, there exists a series of small...
Basin of Maryland
Maryland
Maryland is a U.S. state located in the Mid Atlantic region of the United States, bordering Virginia, West Virginia, and the District of Columbia to its south and west; Pennsylvania to its north; and Delaware to its east...
. It is found primarily in Washington County
Washington County, Ohio
Washington County is a county located in the state of Ohio. As of the 2010 census, the population was 61,778. Its county seat is Marietta. The county, the oldest in the state, is named for George Washington. Washington County is included in the Parkersburg-Marietta-Vienna, West Virginia-Ohio...
. It is notable for being one of the few areas of Permian sediment east of the Mississippi River
Mississippi River
The Mississippi River is the largest river system in North America. Flowing entirely in the United States, this river rises in western Minnesota and meanders slowly southwards for to the Mississippi River Delta at the Gulf of Mexico. With its many tributaries, the Mississippi's watershed drains...
. In addition, it is the youngest surface rock in the state of Ohio.
It consists of Red and green shale
Shale
Shale is a fine-grained, clastic sedimentary rock composed of mud that is a mix of flakes of clay minerals and tiny fragments of other minerals, especially quartz and calcite. The ratio of clay to other minerals is variable. Shale is characterized by breaks along thin laminae or parallel layering...
, siltstone
Siltstone
Siltstone is a sedimentary rock which has a grain size in the silt range, finer than sandstone and coarser than claystones.- Description :As its name implies, it is primarily composed of silt sized particles, defined as grains 1/16 - 1/256 mm or 4 to 8 on the Krumbein phi scale...
, and sandstone
Sandstone
Sandstone is a sedimentary rock composed mainly of sand-sized minerals or rock grains.Most sandstone is composed of quartz and/or feldspar because these are the most common minerals in the Earth's crust. Like sand, sandstone may be any colour, but the most common colours are tan, brown, yellow,...
, with thin lenticular beds of argillaceous limestone
Limestone
Limestone is a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate . Many limestones are composed from skeletal fragments of marine organisms such as coral or foraminifera....
and thin beds of impure coal
Coal
Coal is a combustible black or brownish-black sedimentary rock usually occurring in rock strata in layers or veins called coal beds or coal seams. The harder forms, such as anthracite coal, can be regarded as metamorphic rock because of later exposure to elevated temperature and pressure...
The base of the layer contains thick-bedded, white conglomeratic
Conglomerate (geology)
A conglomerate is a rock consisting of individual clasts within a finer-grained matrix that have become cemented together. Conglomerates are sedimentary rocks consisting of rounded fragments and are thus differentiated from breccias, which consist of angular clasts...
sandstone. The layer's thickness is greater than 200 feet in Maryland.
The fossils found in the Dunkard Group are similar to ones found in Texas
Texas
Texas is the second largest U.S. state by both area and population, and the largest state by area in the contiguous United States.The name, based on the Caddo word "Tejas" meaning "friends" or "allies", was applied by the Spanish to the Caddo themselves and to the region of their settlement in...
and Oklahoma
Oklahoma
Oklahoma is a state located in the South Central region of the United States of America. With an estimated 3,751,351 residents as of the 2010 census and a land area of 68,667 square miles , Oklahoma is the 28th most populous and 20th-largest state...
of similar age.
Fauna of the Dunkard Group
- DimetrodonDimetrodonDimetrodon was a predatory synapsid genus that flourished during the Permian period, living between 280–265 million years ago ....
- CtenospondylusCtenospondylusCtenospondylus, was a pelycosaur that was about 3 meters long. It lived from Latest Carboniferous to Early Permian. Its fossils were found in the U.S. states of Ohio and Texas. It was a carnivore and preyed upon animals close to its size...
- ArchaeothyrisArchaeothyrisArchaeothyris was a very early mammal-like reptile, which lived in the late Carboniferous period. Dated to 306 million years ago, it is the oldest undisputed synapsid known....
- EdaphosaurusEdaphosaurusEdaphosaurus is a genus of prehistoric synapsid which lived around 303 to 265 million years ago, during the late Carboniferous to early Permian periods. The name Edaphosaurus means "ground lizard" and is derived from the Greek edaphos/εδαφος and σαυρος/sauros...
- EryopsEryopsEryops meaning "drawn-out face" because most of its skull was in front of its eyes is a genus of extinct, semi-aquatic amphibian found primarily in the Lower Permian-aged Admiral Formation of Archer County, Texas, but fossils are also found in New Mexico and parts of the eastern United...
- XenacanthusXenacanthusXenacanthus is a genus of prehistoric sharks. The first species of the genus lived in the later Devonian period, and they survived until the end of the Triassic, 202 million years ago. Fossils of various species have been found worldwide....
- OphiacodonOphiacodonOphiacodon was a large pelycosaur. Its fossils were found in Joggins, Nova Scotia, Canada.Ophiacodon was at least two meters in length, and the largest species were up to . It is estimated to have weighed from . The size of the various species increased during the Early Permian epoch until its...
- DiploceraspisDiploceraspisDiploceraspis was a lepospondyl amphibian. It lived in Ohio during the Permian period. It closely resembles Diplocaulus, and is a relative. It generally sports the same features as Diplocaulus....
- DiplocaulusDiplocaulusDiplocaulus is an extinct genus of leponspondyl amphibian from the Permian period of North America.- Description :...
- BaldwinonusBaldwinonusBaldwinonus is an extinct genus of non-mammalian synapsid.-References:*...
- ProtorothyrisProtorothyrisProtorothyris is an extinct genus of Early Permian protorothyridid known from Texas and West Virginia of the United States. It was first named by Llewellyn Ivor Price in 1937 and the type species is Protorothyris archeri. P...
- DiadectesDiadectesDiadectes was a genus of large, very reptile-like amphibians that lived during the early Permian period...
- IsodectesIsodectesIsodectes is an extinct genus of dvinosaurian temnospondyl within the family Eobrachyopidae. The genus Saurerpeton, named in 1909, is considered to be a junior synonym of Isodectes....
- SagenodusSagenodusSagenodus is an extinct genus of prehistoric sarcopterygian or lobe-finned fish.-See also:* Sarcopterygii* List of sarcopterygians* List of prehistoric bony fish...
- BrachydectesBrachydectesBrachydectes is an extinct genus of lysorophian amphibian that lived from the Carboniferous.- Sources :* Gaining Ground: The Origin and Early Evolution of Tetrapods by Jennifer A. Clack...
- PhlegethontiaPhlegethontiaPhlegethontia is an extinct genus of lepospondyl amphibian from the Carboniferous and Permian periods of Europe and North America.Phlegethontia was an aïstopod, a group of legless, burrowing, snake-like amphibians...