The Rockwell Formation is a late
Devonian
The Devonian ( ) is a period (geology), geologic period and system (stratigraphy), system of the Paleozoic era (geology), era during the Phanerozoic eon (geology), eon, spanning 60.3 million years from the end of the preceding Silurian per ...
and early
Mississippian mapped bedrock unit in
West Virginia
West Virginia is a mountainous U.S. state, state in the Southern United States, Southern and Mid-Atlantic (United States), Mid-Atlantic regions of the United States.The United States Census Bureau, Census Bureau and the Association of American ...
,
Maryland
Maryland ( ) is a U.S. state, state in the Mid-Atlantic (United States), Mid-Atlantic region of the United States. It borders the states of Virginia to its south, West Virginia to its west, Pennsylvania to its north, and Delaware to its east ...
, and
Pennsylvania
Pennsylvania, officially the Commonwealth of Pennsylvania, is a U.S. state, state spanning the Mid-Atlantic (United States), Mid-Atlantic, Northeastern United States, Northeastern, Appalachian, and Great Lakes region, Great Lakes regions o ...
, in the United States.
Description
The Rockwell Formation was described at its type section at
Rockwell Run in West Virginia as soft
arkosic sandstone
Sandstone is a Clastic rock#Sedimentary clastic rocks, clastic sedimentary rock composed mainly of grain size, sand-sized (0.0625 to 2 mm) silicate mineral, silicate grains, Cementation (geology), cemented together by another mineral. Sand ...
, fine hard
conglomerate, and buff hackly
shale
Shale is a fine-grained, clastic sedimentary rock formed from mud that is a mix of flakes of Clay mineral, clay minerals (hydrous aluminium phyllosilicates, e.g., Kaolinite, kaolin, aluminium, Al2Silicon, Si2Oxygen, O5(hydroxide, OH)4) and tiny f ...
.
[
The formation was originally described in West Virginia by Stose and Swartz (1912).][ It was first described in Maryland by H. E. Vokes (1957),][Vokes, H.E., 1957, Geography and geology of Maryland: Maryland Geological Survey Bulletin, no. 19, p. 243.] and later described in central Pennsylvania by C. R. Wood (1980).[Wood, C.R., 1980, Summary groundwater resources of Centre County, Pennsylvania: Pennsylvania Geological Survey Water Resource Report, 4th series, no. 48, p. 60.]
Stratigraphy
The Rockwell is generally considered a Formation. At Formation rank, it has several members, including the Patton and Riddlesburg Shale Members,[Kammer, T.W., and Bjerstedt, T.W., 1986, Stratigraphic framework of the Price Formation (Upper Devonian-Lower Mississippian) in West Virginia: Southeastern Geology, v. 27, no. 1, p. 13-33.] and the Finzel Tongue.[
It has been reduced in rank to a member of the Price Formation in West Virginia.][
The Rockwell is a lateral equivalent of the Huntley Mountain Formation and the Spechty Kopf Formation, as all three underlie the prominent Pocono Formation and its lateral equivalent, the Burgoon Sandstone.
Lessing, Dean, and Kulander (1992) mapped the Meadow Branch synclinorium in ]Berkeley County, West Virginia
Berkeley County is located in the Shenandoah Valley in the eastern panhandle region of West Virginia in the United States. The county is part of the Hagerstown–Martinsburg metropolitan area. As of the 2020 United States census, 2020 census, t ...
, and noted that the Rockwell is approximately 200 meters thick here and that a 2-meter thick diamictite
Diamictite (; from Ancient Greek (): 'through' and (): 'mixed') is a type of lithified sedimentary rock that consists of nonsorted to poorly sorted terrigenous sediment containing particles that range in size from clay to boulders, suspended ...
is present near the base.[Lessing, Peter, Dean, S.L., and Kulander, B.R., 1992, Stratigraphy and structure of Meadow Branch synclinorium, West Virginia: Southeastern Geology, v. 32, no. 3, p. 166-174.]
See also
*Geology of Pennsylvania
The Geology of Pennsylvania consists of six distinct physiographic provinces, three of which are subdivided into different sections. Each province has its own economic advantages and geologic hazards and plays an important role in shaping every ...
* Huntley Mountain Formation
References
{{Chronostratigraphy of Maryland
Devonian System of North America
Mississippian United States
Sandstone formations of the United States
Shale formations of the United States
Devonian Maryland
Devonian geology of Pennsylvania
Devonian Pennsylvania
Devonian West Virginia
Geologic formations of Maryland
Geologic formations of Pennsylvania
Geologic formations of West Virginia
Conglomerate formations