Alum Bluff Group: Difference between revisions

Alum Bluff Group
Alum Bluff Group
Stratigraphic range: Neogene
Type	Group
Location
Region	Georgia (U.S. state), Florida, Alabama
Country	United States

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The Alum Bluff Group is a geologic group in the states of Georgia, Florida, and Alabama. It preserves fossils dating back to the Neogene period.

Age

Period: Paleogene to Neogene
Epoch: Late Oligocene to Early Miocene
Faunal stage: Chattian through Hemphillian ~23.03–5.33 mya, calculates to a period of 17.7 million years

Location

The Alum Bluff Group replaces the Hawthorn Group west of the Apalachicola River with occurrences in Bay, Calhoun, Holmes, Jackson, Liberty, Okaloosa, Walton, and Washington counties. It is younger than the Torreya Formation to the east based on superpositioning.

The Alum Bluff Group outcrops beneath a thin overburden in the western panhandle from river valleys in Okloosa County eastward to western Jackson County.

Lithology

The group is composed of clays, sands and shell beds. These vary from fossil bearing sandy clays to sands, clays, and carbonate beds absent of fossil content with glauconite and phosphate mica which is common. The coloration is from cream to olive gray with mottled reddish brown in the weathered sections. The sands are soft and very fine to coarse with sporadic gravel while carbonate lenses are quite hard. Permeability of the sediments are generally low and are part of the intermediate confining unit/aquifer system.^[1]^[2]

Subdivision

The Alum Bluff Group are defined by the stratigraphic position and mollusks contained within. The group includes:

The Alum Bluff Group has a residuum on Miocene sediments and undifferentiated sediment of the Miocene. This consists of reddish brown, variably sandy clay with inclusions of variably fossiliferous, silicified limestone. The residuum includes Lower to Upper Miocene and younger weathered sediments.^[3]

Fossils

Mollusks both herbivorous and carnivorous in equal percentages.^[4]
Filter feeders at ~7%

References

Various Contributors to the Paleobiology Database. "Fossilworks: Gateway to the Paleobiology Database". Retrieved 17 December 2021.
Finch, J., Geological essay on the Tertiary formation in America: American Journal of Science, v. 7, p. 31–43, 1823.

@@ Line 24: / Line 24: @@
 The '''Alum Bluff Group''' is a [[Group (geology)|geologic group]] in the states of [[Georgia (U.S. state)|Georgia]], [[Florida]], and [[Alabama]]. It preserves [[fossils]] dating back to the [[Neogene]] [[Period (geology)|period]].
+==Age==
+'''[[Period (geology)|Period]]''': [[Paleogene]] to [[Neogene]]<br />
+'''[[Epoch (geology)|Epoch]]''': [[Late Oligocene]] to [[Early Miocene]]<br />
+'''[[Faunal stage]]''': [[Chattian]] through [[Hemphillian]] ~23.03–5.33 [[Mya (unit)|mya]], calculates to a period of {{Mya|23.03-5.33|million years}}
+==Location==
+The Alum Bluff Group replaces the [[Hawthorn Group]] west of the [[Apalachicola River]] with occurrences in [[Bay County, Florida|Bay]], [[Calhoun County, Florida|Calhoun]], [[Holmes County, Florida|Holmes]], [[Jackson County, Florida|Jackson]], [[Liberty County, Florida|Liberty]], [[Okaloosa County, Florida|Okaloosa]], [[Walton County, Florida|Walton]], and [[Washington County, Florida|Washington]] counties. It is younger than the [[Torreya Formation]] to the east based on superpositioning.
+The Alum Bluff Group [[outcrop]]s beneath a thin [[overburden]] in the western panhandle from river valleys in [[Okaloosa County, Florida|Okloosa County]] eastward to western Jackson County.
+==Lithology==
+The group is composed of [[clay]]s, [[sand]]s and shell beds. These vary from fossil bearing sandy clays to sands, clays, and [[carbonate]] beds absent of fossil content with [[glauconite]] and phosphate [[mica]] which is common. The coloration is from cream to olive gray with mottled reddish brown in the weathered sections. The sands are soft and very fine to coarse with sporadic [[gravel]] while carbonate lenses are quite hard. Permeability of the sediments are generally low and are part of the intermediate confining unit/aquifer system.<ref>{{Cite web |url=http://sofia.usgs.gov/publications/maps/florida_geology/units.html |title=United States Geological Survey: Lithostratigraphic Units |access-date=2018-08-07 |archive-date=2018-08-07 |archive-url=https://web.archive.org/web/20180807125409/https://sofia.usgs.gov/publications/maps/florida_geology/units.html |url-status=dead }}</ref><ref>[https://books.google.com/books?id=vxRNAAAAMAAJ&output=pdf&sig=ACfU3U0e2VrarMyw36S5vkr4pBrKOlCyNg&source=gbs_v2_summary_r&cad=0 Matson, George Charles, The phosphate deposits of Florida, Bulletin - United States Geological Survey, 1915]</ref>
+== Subdivision ==
+The Alum Bluff Group are defined by the stratigraphic position and [[mollusks]] contained within. The group includes:
+* [[Chipola Formation]]
+* Oak Grove Sand
+* [[Shoal River Formation]]
+* [[Choctawhatchee Formation]]
+* [[Jackson Bluff Formation]]
+The Alum Bluff Group has a [[residuum on Miocene]] sediments and [[undifferentiated sediment]] of the Miocene. This consists of reddish brown, variably sandy clay with inclusions of variably fossiliferous, silicified limestone. The residuum includes Lower to Upper Miocene and younger weathered sediments.<ref>[https://mrdata.usgs.gov/geology/state/sgmc-unit.php?unit=FLMIab%3B0 United States Geological Survey: Alum Bluff Group]</ref>
+==Fossils==
+*[[Mollusks]] both herbivorous and carnivorous in equal percentages.<ref>[http://gsa.confex.com/gsa/2008SE/finalprogram/abstract_136744.htm Kline, H., Herbert, G., Harries, P., Oches, E., CHES, E., and Portell, R., Trophic Structure OF Shell Beds from the Early Miocene Chipola Formations of Florida]</ref>
+*[[Filter feeder]]s at ~7%
 ==See also==
-{{Portal|Earth sciences|Georgia|Paleontology|Neogene|Cenozoic}}
+{{Portal|Earth sciences|Georgia (U.S. state)|Paleontology}}
 * [[List of fossiliferous stratigraphic units in Georgia (U.S. state)]]
 * [[Paleontology in Georgia (U.S. state)]]
 ==References==
+<references />
-* {{cite web|title= Fossilworks: Gateway to the Paleobiology Database|author= Various Contributors to the Paleobiology Database|url= http://www.fossilworks.org/|accessdate= 22 June 2014}}
+* {{cite web|title= Fossilworks: Gateway to the Paleobiology Database|author= ((Various Contributors to the Paleobiology Database))|url= http://www.fossilworks.org/cgi-bin/bridge.pl?action=home|access-date= 17 December 2021}}
+*<small>Finch, J., Geological essay on the Tertiary formation in America: American Journal of Science, v. 7, p.&nbsp;31–43, 1823.</small>
+==Further reading==
-[[Category:Geologic groups of Georgia (U.S. state)]]
+*<small>Berkenkotter, Richard D,  Application of statistical analysis in evaluating bedded deposits of variable thickness—Florida phosphate data (United States. Bureau of Mines. Report of investigations, U.S. Dept. of the Interior, Bureau of Mines (1964)</small>
+* [https://pubs.usgs.gov/pp/0142f/report.pdf Gardner J.A. (1937). The molluscan fauna of the Alum Bluff Group of Florida. Part VI. Pteropoda, Opisthobranchia and Ctenobranchia (in part). United States Geological Survey Professional Paper. 142-F: 251–435, pls 37–48]
+[[Category:Geologic groups of Georgia (U.S. state)]]
-{{GeorgiaUS-geologic-formation-stub}}