Juniata Formation

From Wikipedia, the free encyclopedia
Jump to navigation Jump to search

Script error: No such module "Infobox".Template:Template otherScript error: No such module "check for unknown parameters".

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

File:Tuscarora Formation interbedding 3.jpg
Conformable contact of overlying Tuscarora Formation (white rock, left) with underlying Juniata Formation (red rock, right) at the Narrows along rt. 30 in Bedford County, Pennsylvania.
File:Slickensides juniata.jpg
Sample from roadcut on U.S. Route 322 near State College, Pennsylvania, showing slickensides

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.[1][2] 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,[2] and conformably below the Tuscarora Formation.[3]

Economic use

The Juniata is a good source of road material, riprap and building stone.[4]

References

<templatestyles src="Reflist/styles.css" />

  1. Berg, T.M., Edmunds, W.E., Geyer, A.R. and others, compilers, (1980). Geologic Map of Pennsylvania: Pennsylvania Geologic Survey, Map 1, scale 1:250,000.
  2. a b Script error: No such module "citation/CS1".
  3. Berg, T.M., et al., (1983). Stratagraphic Correlation Chart of Pennsylvania: G75, Pennsylvania Geologic Survey, Harrisburg, Pennsylvania.
  4. Script error: No such module "Citation/CS1".

Script error: No such module "Check for unknown parameters".

See also

Template:Chronostratigraphy of Virginia Template:Stratigraphic column of West Virginia


Template:Maryland-geologic-formation-stub