Girish Mahajan (Editor)

Tonoloway Formation

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Type
  
sedimentary

Other
  
Thickness
  
250+/-20 m

Named by
  
E. O. Ulrich, 1911

Primary
  
Limestone

Underlies
  
Tonoloway Formation httpsuploadwikimediaorgwikipediacommonsthu

Named for
  
Tonoloway Ridge, Rock Ford, WV

Roadcut of keyser and tonoloway formations


The Late Silurian Tonoloway Formation is a mapped limestone bedrock unit in Pennsylvania, Maryland, Virginia and West Virginia.

Contents

Description

The basal 50 m consists of medium-dark-gray laminated to thin-bedded calcisiltite 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 the Keyser Formation.

Depositional environment

The depositional environment of the Tonoloway is interpreted as shallow marine.

Notable exposures

  • Tonoloway Ridge (type section), in Pennsylvania, Maryland, and West Virginia.
  • Along Little Juniata River, 2 km northeast of Bellwood, Pennsylvania
  • Blue Rock, and other large outcroppings, in the Smoke Hole Canyon of eastern West Virginia
  • Trout Pond, in Hardy County, West Virginia
  • Age

    Relative age dating places the Tonoloway in the late Silurian.

    References

    Tonoloway Formation Wikipedia


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