Bigfork Chert
Geologic formation in Arkansas and Oklahoma, United States
From Wikipedia, the free encyclopedia
The Bigfork Chert is a Middle to Late Ordovician geologic formation in the Ouachita Mountains of Arkansas and Oklahoma. First described in 1892,[4] this unit was not named until 1909 by Albert Homer Purdue in his study of the Ouachita Mountains of Arkansas.[3] Purdue assigned the town of Big Fork in Montgomery County, Arkansas as the type locality, but did not designate a stratotype. As of 2017, a reference section for this unit has yet to be designated. The Bigfork Chert is known to produce planerite, turquoise, variscite, and wavellite minerals.[5]
| Bigfork Chert | |
|---|---|
| Stratigraphic range: Ordovician | |
| Type | Formation |
| Unit of | none |
| Sub-units | none |
| Underlies | Polk Creek Shale[1] |
| Overlies | Womble Shale |
| Thickness | 450 to 750 feet[2] |
| Lithology | |
| Primary | Chert |
| Location | |
| Region | Arkansas, Oklahoma |
| Country | United States |
| Type section | |
| Named for | Big Fork, Montgomery County, Arkansas |
| Named by | Albert Homer Purdue[3] |
