| 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 Formation is a mappedlimestonebedrock unit inPennsylvania,Maryland,Virginia andWest Virginia. The Tonoloway is roughly equivalent to the Salina group that is found to the north and west.
The basal 50 m consists of medium-dark-gray laminated to thin-beddedcalcisiltite with 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]
Thedepositional environment of the Tonoloway is interpreted as shallow marine.
Relative age dating places the Tonoloway in the lateSilurian.
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