Description

The McKenzie Formation is a Gray, thin-bedded 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...

 and 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....

, with interbedded red sandstone and shale in its eastern extents in Maryland. The thickness ranges from 160 to 380 feet.

Age

Relative age dating of the Tuscarora places it in the Silurian

Silurian

The Silurian is a geologic period and system that extends from the end of the Ordovician Period, about 443.7 ± 1.5 Mya , to the beginning of the Devonian Period, about 416.0 ± 2.8 Mya . As with other geologic periods, the rock beds that define the period's start and end are well identified, but the...

 period. It rests conformably atop the Clinton Group

Clinton Group

The Silurian Clinton Group is a mapped bedrock unit in New York, Pennsylvania, Maryland, and West Virginia. It contains the Rochester Shale, Rose Hill Formation and the ridge-forming Keefer Formation...

 and conformably below the Bloomsburg Formation

Bloomsburg Formation

The Silurian Bloomsburg Formation is a mapped bedrock unit in Pennsylvania, New Jersey, New York and Maryland. It is named for the Town of Bloomsburg, Pennsylvania for which it was first described. The Bloomsburg marked the first occurrence of red sedimentary rocks in the Appalachian Basin...

.