Thunder Bay Limestone Explained

Thunder Bay Limestone
Type:Geological formation
Period:Devonian
Unitof:Traverse Group
Subunits:Partidge Point Member, Potter Farm Member, and Norway Point Member
Underlies:Kettle Point Formation and Squaw Bay Limestone
Overlies:Potter Farm Formation

The Thunder Bay Limestone is a geologic formation in Michigan. It preserves fossils dating back to the Devonian period.

Fossil content

Vertebrates

Conodonts

Conodonts reported from the Thunder Bay Limestone
Genus Species Presence MaterialNotes Images
IcriodusI. cymbiformis[1] Also found in the Detroit River, Traverse, Antrim, Ferron Point, Genshaw, Alpena and Norway Point formations.
I. expansusAlso found in the Detroit River, Traverse, Antrim, Lucas, Anderdon, Dundee, Bell, Ferron Point, Genshaw, Alpena, Potter Farm and Norway Point formations.
I. latericrescens latericrescensAlso found in the Traverse, Bell, Ferron Point, Genshaw, Newton Creek, Alpena, Four Mile Dam,,Norway Point and Potter Farm formations.
PolygnathusP. varcusAlso found in the Traverse, Antrim, Alpena, Four Mile Dam and Norway Point formations.

Placoderms

Invertebrates

Brachiopods

Brachiopods reported from the Thunder Bay Limestone
Genus Species Presence MaterialNotes Images
PentamerellaP. proteus[2]
SpinulicostaS. mutocostaAlso found in the Bell, Rockport Quarry, Ferron Point, Four Mile Dam, Beebe School and Potter Farm formations.

Echinoderms

Echinoderms reported from Thunder Bay Limestone
Genus Species Presence MaterialNotes Images
CorocrinusC. pettyesiBluffs on northeast shore of Partridge Point, 4 miles south of Alpena, Alpena County.[4] A crinoid.
GennaeocrinusG. romingeriBluffs on northeast shore of Partridge Point, 4 miles south of Alpena, Alpena County.A crinoid.

Trilobites

Trilobites reported from the Thunder Bay Limestone
Genus Species Presence MaterialNotes Images
DechenellaD. (Basidechenella) reimanniAlpena County, Michigan.[5]
D. (Basidechenella) sp. CAlpena County, Michigan.A single specimen.
DipleuraD. dekayiPartridge Point on Thunder Bay, about 4 miles south of Alpena.Also found in the Norway Point Formation.
GreenopsG. alpenensisAlpena County, Michigan.
PhacopsP. iowensisAlpena County, Michigan.Also found in the Potter Farm and Petoskey formations.
ProetusP. (Crassiproetus) alpenensisAlso found in the Potter Farm Formation.

See also

References

Notes and References

  1. Orr . R. William . 1971 . Conodonts from Middle Devonian Strata from the Michigan Basin . en-US.
  2. Imbrie . John . 1959 . 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 . en-US.
  3. Watkins . J. Lloyd . 1959 . Middle Devonian Auloporid Corals from the Traverse Group of Michigan . Journal of Paleontology . 33 . 5 . 793–808 . 0022-3360.
  4. Kesling . Robert V. . 1964 . Two New Crinoids of the Family Periechocrinitidae from the Middle Devonian Thunder Bay Limestone of Michigan . Contributions from the Museum of Paleontology, University of Michigan . en-US . XIX . 11 . 143–155.
  5. Stumm. Erwin. 1953. Trilobites of the Devonian Traverse Group of Michigan. University of Michigan Press - Museum of Paleontology.