Traverse Group
The Traverse Group is a geologic group in Michigan, comprising middle Devonian limestones with calcareous shale components.[1][2] Its marine fossils notably include Michigan's state stone, the Petoskey stone (the extinct coral Hexagonaria percarinata), among other corals and records of ancient marine life. A range of trilobites has also been found in the Traverse Group.[3]
Traverse Group Stratigraphic range: Devonian | |
---|---|
Type | Group |
Sub-units | Bell Shale, Rockport Quarry Limestone, Ferron Point Fm, Koehler Limestone, Gravel Point Fm, Charlevoix Limestone, Petoskey Fm, Whiskey Creek Fm |
Underlies | Antrim Shale and Jordan River Formation |
Overlies | Dundee Formation and Rogers City Limestone |
Thickness | 183 meters |
Lithology | |
Other | Limestone |
Location | |
Region | |
Country |
The Traverse Group outcrops in Emmet and Charlevoix counties along the northwestern shore of Michigan's lower peninsula. Its formations are Gravel Point, Charlevoix Limestone, Petoskey, and Whiskey Creek.[4] The Gravel Point Formation consists of a lithographic gray to brown limestone with shale beds up to 0.5 meters thick; it also includes chert nodules and bioherms (fossilized reef mounds). The Charlevoix Limestone is a mildly argillaceous limestone with interbedded coquina. The Petoskey Formation is an arenaceous limestone named for its locale (Petoskey, Michigan), and contains the eponymous Petoskey stones. The Whiskey Creek Formation is a limestone.
The Traverse Group formed as a shallow carbonate shelf during the Devonian period (~419 to 359 Ma), when the most recent supercontinent, Pangea, was just beginning to take shape.
References
- "Traverse Group (MIDt;0)". mrdata.usgs.gov. Retrieved 2016-06-29.
- John., Imbrie (1959-01-01). "Brachiopods of the Traverse group (Devonian) of Michigan. Part 1, Dalmanellacea, Pentameracea, Strophomenacea, Orthotetacea, Chonetacea, and Productacea. Bulletin of the AMNH ; v. 116, article 4". Cite journal requires
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(help) - Stumm, Erwin (1953). "Trilobites of the Devonian Traverse Group of Michigan" (PDF). University of Michigan Press - Museum of Paleontology.
- Milstein, Randall (1987). "Middle Devonian Traverse Group in Emmet and Charlevoix Counties, Michigan" (PDF). Geological Society of America Centennial Field Guide - North-Central Section.
- Various Contributors to the Paleobiology Database. "Fossilworks: Gateway to the Paleobiology Database". Archived from the original on 31 July 2014. Retrieved 22 June 2014.