Chickies Formation
Chickies Formation | |
---|---|
Stratigraphic range: Cambrian | |
Type | metamorphic |
Sub-units | Hellam Conglomerate Member |
Lithology | |
Primary | quartzite |
Other | slate, schist |
Location | |
Region | Mid-Atlantic United States |
Country | ![]() |
Extent | Pennsylvania, New Jersey, Maryland |
Type section | |
Named for | Chickies Rock |
Named by | J. Peter Lesley, 1876 |
![](http://upload.wikimedia.org/wikipedia/commons/thumb/f/f9/Bulletin_799_Plate_8B_Chickies_Banded_Slate.jpg/240px-Bulletin_799_Plate_8B_Chickies_Banded_Slate.jpg)
![](http://upload.wikimedia.org/wikipedia/commons/thumb/4/40/Bulletin_799_Plate_8C_Mica_Schist_from_Upper_Beds_of_Chickies_Quartzite.jpg/240px-Bulletin_799_Plate_8C_Mica_Schist_from_Upper_Beds_of_Chickies_Quartzite.jpg)
The Cambrian Chickies Formation is a mapped bedrock unit in Pennsylvania, New Jersey, and Maryland. It is named for Chickies Rock, north of Columbia, Pennsylvania along the Susquehanna River.
Description
The Chickies Formation is described as a light-gray to white, hard, massive quartzite and quartz schist with thin interbedded dark slate at the top. Included at the base is the Hellam Conglomerate Member. It is a rare metamorphic rock that has fossils; Skolithos is found throughout the formation.[1]
Depositional age
Relative age dating places the Chickies in the Lower Cambrian Period, deposited between 542 and 520 million years ago (±2 million years).[2]
Economic uses
The Chickies is quarried as a building stone and for aggregate. The stone used to build the restrooms at Valley Forge National Historical Park is Chickies quartzite.[3]
See also
References
- ^ 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.
- ^ Blackmer, G.C., (2005). Preliminary Bedrock Geologic Map of a Portion of the Wilmington 30- by 60-Minute Quadrangle, Southeastern Pennsylvania. Pennsylvania Geologic Survey, Open-File Report OFBM-05-01.0.
- ^ http://www.dcnr.state.pa.us/topogeo/ParkGuides/pg08.pdf