The Rockwell Formation is a late Devonian

Devonian

The Devonian is a geologic period and system of the Paleozoic Era spanning from the end of the Silurian Period, about 416.0 ± 2.8 Mya , to the beginning of the Carboniferous Period, about 359.2 ± 2.5 Mya...

 and early Mississippian mapped bedrock unit in 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...

, 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...

, and 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...

, in the United States.

Description

The Rockwell Formation was described at its type section at Rockwell Run

Rockwell Run

Rockwell Run is a mountain stream in Morgan County, West Virginia. It is a tributary of the Potomac River.The Rockwell Formation is named after Rockwell Run, where exposures of the formation were first described by Stose and Swartz in 1912.-References:...

 in West Virginia as soft arkosic

Arkose

Arkose is a detrital sedimentary rock, specifically a type of sandstone containing at least 25% feldspar. Arkosic sand is sand that is similarly rich in feldspar, and thus the potential precursor of arkose....

 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,...

, fine hard conglomerate

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...

, and buff hackly 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...

.

The formation was originally described in West Virginia by Stose and Swartz (1912). It was first described in Maryland by H. E. Vokes (1957), and later described in central Pennsylvania by C. R. Wood (1980).

Stratigraphy

The Rockwell is generally considered a Formation. At Formation rank, it has several members, including the Patton and Riddlesburg Shale Members, 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

Huntley Mountain Formation

The Huntley Mountain Formation is a late Devonian and early Mississippian mapped bedrock unit in Pennsylvania, in the United States.-Description:The formation is composed of relatively soft grayish-red shale and olive-gray sandstone...

 and the Spechty Kopf Formation, as all three underlie the prominent Pocono Formation

Pocono Formation

The Mississippian Pocono Formation is a mapped bedrock unit in Pennsylvania, Maryland, and West Virginia, USA. It is also known as the Pocono Group in Maryland and West Virginia,...

 and its lateral equivalent, the Burgoon Sandstone.

Lessing, Dean, and Kulander (1992) mapped the Meadow Branch synclinorium

Syncline

In structural geology, a syncline is a fold, with younger layers closer to the center of the structure. A synclinorium is a large syncline with superimposed smaller folds. Synclines are typically a downward fold, termed a synformal syncline In structural geology, a syncline is a fold, with younger...

 in Berkeley County, West Virginia

Berkeley County, West Virginia

Berkeley County is a county located in the Eastern Panhandle region of the U.S. state of West Virginia. As of 2010, the population is 104,169, making it the second-most populous county in West Virginia, behind Kanawha...

, and noted that the Rockwell is approximately 200 meters thick here and that a 2 meter thick diamictite

Diamictite

Diamictite : through and µεικτός : mixed) is a poorly or non-sorted conglomerate or breccia with a wide range of clasts, up to 25% of them gravel sized...

is present near the base.