Juniata Formation
# Juniata Formation

The Ordovician Juniata Formation is a mapped bedrock unit in Pennsylvania, West Virginia, Virginia, Tennessee, and Maryland. It is a relative slope-former occurring between the two prominent ridge-forming sandstone units: the Tuscarora Formation and the Bald Eagle Formation in the Appalachian Mountains.

## Description

The Juniata is defined as a grayish-red to greenish-gray, thin- to thick-bedded siltstone, shale, and very fine to medium-grained crossbedded sandstone or subgraywacke and protoquartzite with interbedded conglomerate. The Juniata is a lateral equivalent of the Queenston Shale in western Pennsylvania.

### Depositional environment

The depositional environment of the Juniata has always been interpreted as mostly terrestrial or shallow marine deposits resulting in a molasse sequence produced by the Taconic orogeny.

### Fossils

Very few fossils exist in the Juniata Formation, but different types of trace fossils such as tracks and burrows can commonly be found.

## Age

Relative age dating of the Juniata places it in the Upper Ordovician period, being deposited between 488.3 and 443.7 (±10) million years ago. It rests conformably atop the Bald Eagle Formation in Pennsylvania and the Martinsburg Formation in Maryland, and conformably below the Tuscarora Formation.

## Economic use

The Juniata is a good source of road material, riprap and building stone.

