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| unitof =
| unitof =
| subunits = *[[Davis Formation]]
| subunits = *[[Davis Formation]]
*[[Eau Claire Formation]]
*[[Franconia Formation]]
*[[Franconia Formation]]
*[[The Galesville Formation]]
*[[Ironton Sandstone]]
*[[Ironton Sandstone]]
*[[Galesville Sandstone]]
Miner's Castle Member
*[[Eau Claire Formation]]
Chapel Rock Member
; [[Michigan]]
Basal Conglomerate
*Miner's Castle Member
*Chapel Rock Member
*Basal Conglomerate
| underlies = [[Au Train Formation]]
| underlies = [[Au Train Formation]]
| overlies = [[Jacobsville Sandstone]]
| overlies = [[Jacobsville Sandstone]]
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Stratigraphically it is equivalent to the Franconia Formation in Illinois and Missouri.<ref>{{Cite web |title=Franconia Formation |url=https://legacy.igws.indiana.edu/compendium/franconia-formation |access-date=2024-03-12 |website=legacy.igws.indiana.edu |language=en}}</ref> In Illinois it is the lower member of the Franconia.
Stratigraphically it is equivalent to the Franconia Formation in Illinois and Missouri.<ref>{{Cite web |title=Franconia Formation |url=https://legacy.igws.indiana.edu/compendium/franconia-formation |access-date=2024-03-12 |website=legacy.igws.indiana.edu |language=en}}</ref> In Illinois it is the lower member of the Franconia.

=== Galesville Sandstone ===
The '''Galesville Sandstone''' is a geologic unit found in Northwestern [[Indiana]] and [[Wisconsin]]. Moving south and west it grades into the Davis Formation. In southern and western Indiana it is a named member of the Davis Formation this continues into Illinois. Named for exposures along [[Beaver Creek (Wisconsin)|Beaver Creek]] in [[Galesville, Wisconsin]]. The formation is fine to coarse grained sandstone. Grading upward towards the Ironton Sandstone. The Galesville ranges from about 50' to 100' thick.<ref>{{Cite web |title=Galesville Sandstone |url=https://legacy.igws.indiana.edu/compendium/galesville-sandstone |access-date=2024-03-14 |website=legacy.igws.indiana.edu |language=en}}</ref>


== References ==
== References ==

Revision as of 15:16, 14 March 2024

Munising Group
Stratigraphic range: Cambrian-Early Ordovician
Light-colored Musining Formation overlying the red Jacobsville Formation in Pictured Rocks National Lakeshore
TypeFormation
Sub-units
Michigan
  • Miner's Castle Member
  • Chapel Rock Member
  • Basal Conglomerate
UnderliesAu Train Formation
OverliesJacobsville Sandstone
Thickness1,700 ft (520 m)
Lithology
PrimaryConglomerate
OtherAnhydrite
Location
Region Michigan
 Ohio
 Ontario
Country United States
 Canada

The Munising Group or Formation is a 1,700 feet (520 m) thick, white to light grey[1] Cambrian sedimentary unit that crops out in Michigan and (to a lesser extent) Ontario. At one end of its extent, it comprises a basal conglomerate overlain by the Chapel Rock Member and the Miners Castle Member; elsewhere, it comprises the Eau Claire, Galesville (=Dresbach), and Franconia Members. Anhydritic evaporite deposits are present in places.[2] The conglomerate was deposited by rivers in flood, with the Chapel Rock member, which contains deltaic deposits, representing transgression as the conglomerate cones became submerged; the Miners Castle member was deposited further from the shoreline, representing shelf deposits.[3] Its uppermost strata may be Early Ordovician in age, and contain conodonts, trilobites and phosphatic moulds of brachiopods, ostrocoderm fish and gastropods.[4]

The Munising lies unconformably above the Jacobsville Formation.[1]

Stratigraphy

Davis Formation

The lampshell Ocnerorthis monticola, Order Rhynchonellida, Family Eoortidae, from Davis Formation. Elwins, MO Upper Cambrian in age

The Davis Formation or Davis Member is found from Missouri through Illinois and into Indiana and Michigan. This formation is Upper Cambrian in age. It is named for Davis Creek located in St. Francois County, Missouri by Buehler (1907, p. 231). The formation is composed of Siltstone, Shale, Limestone and Dolomite. The rock of the Davis Formation is a graditional change between the lower Galesville, Ironton and Franconia Formations to the upper Potosi Dolomite.[5]

Stratigraphically it is equivalent to the Franconia Formation in Illinois and Missouri.[6] In Illinois it is the lower member of the Franconia.

Galesville Sandstone

The Galesville Sandstone is a geologic unit found in Northwestern Indiana and Wisconsin. Moving south and west it grades into the Davis Formation. In southern and western Indiana it is a named member of the Davis Formation this continues into Illinois. Named for exposures along Beaver Creek in Galesville, Wisconsin. The formation is fine to coarse grained sandstone. Grading upward towards the Ironton Sandstone. The Galesville ranges from about 50' to 100' thick.[7]

References

  1. ^ a b "Pictured Rocks: Geologic Formations". US National Park Service. Retrieved August 5, 2011.
  2. ^ Paul A. Catacosinos (1973). "Cambrian Lithostratigraphy of Michigan Basin". The American Association of Petroleum Geologists Bulletin. 57 (12): 2404–2418. doi:10.1306/83d9132b-16c7-11d7-8645000102c1865d.
  3. ^ Charles a. Haddox, R. H. D. (1990). "Cambrian Shoreline Deposits in Northern Michigan". SEPM Journal of Sedimentary Research. doi:10.1306/212F9250-2B24-11D7-8648000102C1865D.
  4. ^ Miller, J. F.; Ethington, R. L.; Rose, R. (2006). "Stratigraphic Implications of Lower Ordovician Conodonts from the Munising and Au Train Formations at Pictured Rocks National Lakeshore, Upper Peninsula of Michigan". PALAIOS. 21 (3): 227–237. doi:10.2110/palo.2004.p04-50.
  5. ^ "Davis Formation". legacy.igws.indiana.edu. Retrieved 2024-03-12.
  6. ^ "Franconia Formation". legacy.igws.indiana.edu. Retrieved 2024-03-12.
  7. ^ "Galesville Sandstone". legacy.igws.indiana.edu. Retrieved 2024-03-14.