Gravel Point Formation
{{Short description|Geological formation}}
{{Infobox rockunit
| name = Gravel Point Formation
| image = Fossiliferous limestone (Gravel Point Formation, Middle Devonian; near South Point, west of Charlevoix, Michigan, USA) 8.jpg
| caption = Fossiliferous limestone from the Gravel Point Formation
| type = Geological formation
| age = {{fossil range|Givetian|Givetian|Middle Devonian (Givetian)}}
| period = Devonian
| prilithology = Limestone
| otherlithology =
| namedfor =
| namedby =
| region = Michigan
| country = United States
| coordinates =
| unitof = Traverse Group
| subunits =
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| overlies =
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The Gravel Point Formation is a geologic formation in western Michigan, United States. It preserves fossils dating back to the middle Devonian period and correlates with the Long Lake Limestone and Alpena Limestone.{{Cite journal |last=Mohan |first=Joseph |date=November 2013 |title=A Paleoenvironmental Analysis of the Middle Devonian Gravel Point Formation, Western Michigan |url=https://www.researchgate.net/publication/297469834 |journal=The Professional Geologist |volume=50 |issue=6 |pages=12–16}}
Description
The Michigan Basin was a shallow marine shelf during the middle Devonian, located between 30º South and 20º North latitude in central Laurasia. According to stratigraphic and paleontological examination, the sediments of the Gravel Point Formation were deposited in a shallow lagoonal reef environment.
Fossil content
=Vertebrates=
==Acanthodians==
class="wikitable" align="center" | ||||
colspan="6" align="center" | Acanthodians of the Gravel Point Formation | ||||
---|---|---|---|---|
Genus | Species | Presence
!Material | Notes | Images |
Gyracanthus
|G. sp. |South Point (Gravel Point), Little Traverse Bay, Charlevoix County.{{Cite journal |last1=Stack |first1=Jack |last2=Sallan |first2=Lauren |date=2018-09-20 |title=An examination of the Devonian fishes of Michigan |url=https://www.researchgate.net/publication/327778213 |journal=PeerJ |volume=6 |issue=2 |pages=e5636 |doi=10.7717/peerj.5636|pmid=30258725 |s2cid=52843222 |doi-access=free |pmc=6151260 }} |A single specimen (UMMP 1329). | A gyracanthid. |
==Bony fish==
class="wikitable" align="center" | ||||
colspan="6" align="center" | Bony fish of the Gravel Point Formation | ||||
---|---|---|---|---|
Genus | Species | Presence
!Material | Notes | Images |
?Onychodus
|?O. sp. |South Point (Gravel Point), Little Traverse Bay, Charlevoix County. |A single specimen (UMMP 14370). | An onychodontiform. |
==Placoderms==
class="wikitable" align="center" | ||||
colspan="6" align="center" | Placoderms of the Gravel Point Formation | ||||
---|---|---|---|---|
Genus | Species | Presence
!Material | Notes | Images |
Holonemiid
| |South Point (Gravel Point), Little Traverse Bay, Charlevoix County. |A single specimen (UMMP 3129). | | |
=Invertebrates=
Several species of ostracods, an unidentified arthropod 'hook', crinoid columnals and several species of polychaetes and scolecodonts are known from the formation.
==Brachiopods==
class="wikitable" align="center" | ||||
colspan="6" align="center" | Brachiopods of the Gravel Point Formation | ||||
---|---|---|---|---|
Genus | Species | Presence
!Material | Notes | Images |
Atrypa
|A. corrugata | | | | ||||
Douvillina
|D. sp. | | | ||||
Heteralosia
|H. sp. B | | | | ||||
Leptalosia
|L. radicans | |Also found in the Norway Point, Alpena, Four Mile Dam, Genshaw, Arkona and Hungry Hollow formations. | | ||||
Longispina
|L. emmetensis | |Also found in the Alpena Limestone and Four Mile Dam Formation. | | ||||
rowspan=2|Mucrospirifer
|M. latus | |A spiriferid. | | ||||
M. sp.
| |A spiriferid. | | ||||
Oligorhachis
|O. oligorhachis | |Also found in the Four Mile Dam Formation. | | ||||
rowspan=2|Orthopleura
|O. sp. A |One specimen (U.S.N.M. no. 124258). | | | ||||
O. sp. B
|One specimen (U.S.N.M. no. 124280). | | | ||||
rowspan="3"|Pentamerella
|P. aftonensis | | | | ||||
P. alpenensis
| |Also found in the Alpena Limestone and Four Mile Dam Formation. | | ||||
P. sp. D
| |A small collection of large shells (the largest being 38 millimeters). | | | ||||
Pholidostrophia
|P. geniculata | |Also found in the Alpena, Widder and Hungry Hollow formations. | | ||||
Pseudoatrypa
|P. keslingi | | | | ||||
Schuchertella
|S. anomala | |Possibly also found in the Four Mile Dam Formation. | | ||||
rowspan="6" |Strophodonta
|S. costata | |A strophomenid. | | ||||
S. cf. S. erotica
| |A strophomenid. | | ||||
S. erratica
| |Also found in the Alpena Limestone and Four Mile Dam Formation. | | ||||
S. fissicosta
| |Also found in the Four Mile Dam Formation. | | ||||
S. nanus
| |Also found in the Alpena Limestone and Four Mile Dam Formation. | | ||||
S. titan titan
| |Also known from the Alpena Limestone. | | ||||
Truncalosia
|T. gibbosa | |Also found in the Alpena, Genshaw, Norway Point, Petoskey and Potter Farm formations, the Arkona Shale and the Hamilton Group. | | ||||
Tylothyris
|T. subvaricosa | |Also found in the Cedar Valley, Milwaukee, Mineola, Bell, Rockport Quarry, Ferron Point, Genshaw, Alpena, Norway Point and Potter Farm formations. | |
==Bryozoans==
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colspan="6" align="center" | Bryozoans of the Gravel Point Formation | ||||
---|---|---|---|---|
Genus | Species | Presence
!Material | Notes | Images |
Fenestellapolypore
|F. magnifica | | A fenestellid. | |
==Cnidarians==
class="wikitable" align="center" | ||||
colspan="6" align="center" | Cnidarians of the Gravel Point Formation | ||||
---|---|---|---|---|
Genus | Species | Presence
!Material | Notes | Images |
rowspan=2|Aulocystis
|A. alectiformis | |Also found in the Alpena Limestone. | | ||||
A. fenestrata
| |Also found in the Alpena Limestone. | | ||||
rowspan="2" |Aulopora
|A. conferta | |Also found in the Bell, Ferron Point, Genshaw, Alpena, Four Mile Dam, Potter Farm, Petoskey and Hungry Hollow formations. | | ||||
A. socialis
| | | | ||||
Favosites
|F. mammilatus | | A tabulate coral. | | ||||
rowspan=2|Pachyphragma
|P. concentricum | |Also found in the Ferron Point, Four Mile Dam and Alpena formations. | | ||||
P. erectum
| |Also found in the Potter Farm and Petoskey formations. | |
==Sponges==
class="wikitable" align="center" | ||||
colspan="6" align="center" | Sponges of the Gravel Point Formation | ||||
---|---|---|---|---|
Genus | Species | Presence
!Material | Notes | Images |
Parallelopora
|P. winchelli | | A stromatoporoid. | |
==Tentaculitans==
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colspan="6" align="center" | Tentaculitans of the Gravel Point Formation | ||||
---|---|---|---|---|
Genus | Species | Presence
!Material | Notes | Images |
Tentaculites
|T. sp. | | A tentaculitid. |
==Trilobites==
{{Paleobiota-key-compact}}
class="wikitable" align="center" | ||||
colspan="6" align="center" | Trilobites of the Gravel Point Formation | ||||
---|---|---|---|---|
Genus | Species | Presence
!Material | Notes | Images |
Ancyropyge
|A. romingeri |"Longispina emmetensis zone".{{Cite journal|last=Stumm|first=Erwin|date=1953|title=Trilobites of the Devonian Traverse Group of Michigan|url=https://deepblue.lib.umich.edu/bitstream/handle/2027.42/48269/ID108.pdf?sequence=2|journal=University of Michigan Press - Museum of Paleontology}} | | | | ||||
Dechenella
|D. (Basidechenella) pulchra | |Also found in the Alpena Limestone and Dock Street clay of the Four Mile Dam Formation. | | ||||
Eldredgeops
|E. rana alpenensis | |Originally reported as Phacops rana alpenensis. Also found in the Alpena Limestone. | ||||
rowspan=2|Greenops
|G. aequituberculatus | |Also found in the Norway Point and Four Mile Dam formations. | | ||||
G. traversensis
| |Also found in the Dock Street clay of the Four Mile Dam Formation. | | ||||
style="background:#f3e9f3;" |Phacops
|style="background:#fbdddb;" |P. rana alpenensis |style="background:#fbdddb;" | |style="background:#fbdddb;" | |style="background:#fbdddb;" |Reassigned to the genus Eldredgeops. |style="background:#fbdddb;" | | ||||
Proetus
|P. (Crassiproetus) traversensis | | Also found in the Four Mile Dam Formation. | |
=Flora=
Algal colonies are known from the formation.
==Acritarchs==
class="wikitable" align="center" | ||||
colspan="6" align="center" | Acritarchs of the Gravel Point Formation | ||||
---|---|---|---|---|
Genus | Species | Presence
!Material | Notes | Images |
Lophosphaeridium
|L. sp. | | | | ||||
Tasmanites
|T. sp. | | | |
==Plants==
class="wikitable" align="center" | ||||
colspan="6" align="center" | Plants of the Gravel Point Formation | ||||
---|---|---|---|---|
Genus | Species | Presence
!Material | Notes | Images |
Ancyrospora
|A. sp. | |Miospores. | | |
See also
{{Portal|Earth sciences|Michigan|Paleontology}}
References
{{reflist}}
- {{cite web|title= Fossilworks: Gateway to the Paleobiology Database|author= ((Various Contributors to the Paleobiology Database))|url= https://www.fossilworks.org|access-date= 17 December 2021|archive-date= 25 March 2022|archive-url= https://web.archive.org/web/20220325060448/http://www.fossilworks.org/cgi-bin/bridge.pl?action=home|url-status= live}}
Category:Devonian southern paleotemperate deposits
Category:Limestone formations of the United States
Category:Long stubs with short prose
{{Michigan-geologic-formation-stub}}