The Traverse Group is a
geologic group
Geology () is a branch of natural science concerned with Earth and other astronomical objects, the features or rocks of which it is composed, and the processes by which they change over time. Modern geology significantly overlaps all other Eart ...
in
Michigan, comprising middle Devonian limestones with calcareous shale components. 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.
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.
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
Coquina () is a sedimentary rock that is composed either wholly or almost entirely of the transported, abraded, and mechanically sorted fragments of the shells of mollusks, trilobites, brachiopods, or other invertebrates. The term ''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
The Devonian ( ) is a geologic period and system of the Paleozoic era, spanning 60.3 million years from the end of the Silurian, million years ago (Mya), to the beginning of the Carboniferous, Mya. It is named after Devon, England, whe ...
period (~419 to 359 Ma), when the most recent
supercontinent,
Pangea, was just beginning to take shape.
See also
*
List of fossiliferous stratigraphic units in Michigan
This article contains a list of fossil-bearing stratigraphic units in the state of Michigan, U.S.
Sites
See also
* Paleontology in Michigan
References
*
{{DEFAULTSORT:Fossiliferous stratigraphic units in Michigan
Michigan
Stratigraphi ...
References
*
Devonian Indiana
Geologic groups of Michigan
{{Michigan-geologic-formation-stub