Tonoloway Formation
Tonoloway Formation | |
---|---|
Stratigraphic range:Pridoli[1] | |
A Tonoloway limestone "fin"known as Blue Rock,Smoke Hole Canyon,West Virginia | |
Type | sedimentary |
Underlies | Keyser Formation |
Overlies | Wills Creek Formation |
Thickness | 250+/-20 m |
Lithology | |
Primary | limestone |
Other | shale |
Location | |
Region | Appalachian Mountains |
Extent | Pennsylvania,Maryland,Virginia,West Virginia |
Type section | |
Named for | Tonoloway Ridge, Rock Ford, WV |
Named by | E. O. Ulrich, 1911[2] |
The LateSilurianTonoloway Formationis a mappedlimestonebedrockunit inPennsylvania,Maryland,VirginiaandWest Virginia.The Tonoloway is roughly equivalent to the Salina group that is found to the north and west.
Description
[edit]The basal 50 m consists of medium-dark-gray laminated to thin-beddedcalcisiltitewith shale partings and interbeds. Overlying 5 m are light-yellowish-gray to olive-gray mudstone and shale. Above this interval are 75 m of laminated calcisiltite with interbeds of thick to very thick bedded calcisiltite. The remainder of the formation is cyclic, consisting of three or four resistant ledges of laminated limestone and shale. Uppermost 20 m contains a variety of limestones. Lower contact with the Wills Creek is probably conformable. Upper contact is conformable and undulatory, occurring at the base of the "calico" limestone of theKeyser Formation.[3]
Depositional environment
[edit]Thedepositional environmentof the Tonoloway is interpreted as shallow marine.
Notable exposures
[edit]- Tonoloway Ridge(type section), in Pennsylvania, Maryland, and West Virginia.
- AlongLittle Juniata River,2 km northeast ofBellwood, Pennsylvania
- Blue Rock, and other large outcroppings, in theSmoke Hole Canyonof eastern West Virginia
- Trout Pond,inHardy County, West Virginia
Age
[edit]Relative age dating places the Tonoloway in the lateSilurian.
References
[edit]- ^Paleozoic Sedimentary Successions of the Virginia Valley & Ridge and Plateau
- ^Ulrich, E.O., 1911, Revision of the Paleozoic systems: Geological Society of America Bulletin, v. 22, p. 281-680.
- ^Faill, R.T., Glover, A.D., and Way, J.H., 1989, Geology and mineral resources of the Blandburg, Tipton, Altoona, and Bellwood quadrangles, Blair, Cambria, Clearfield and Centre Counties, Pennsylvania: Pennsylvania Geological Survey Topographic and Geologic Atlas, 4th series, 86, 209 p., scale 1:24,000 and 1:48,000
- Geologic formations of Pennsylvania
- Silurian Maryland
- Silurian geology of Virginia
- Silurian West Virginia
- Pridoli geology
- Limestone formations of the United States
- Silurian south paleopolar deposits
- Silurian southern paleotemperate deposits
- Southern United States geologic formation stubs
- Maryland geography stubs