The Annona Chalk is a geologic formation in Arkansas, Texas, Louisiana, and Oklahoma.[2] It preserves fossils dating back to the Cretaceous period. The formation is a hard, thick-bedded to massive, slightly fossiliferous chalk. It weathers white, but is blue-gray when freshly exposed. The unit is commercially mined for cement. Fossils in the Annona Chalk include coelenterates, echinoderms, annelids, bivalves, gastropods, cephalopods, and some vertebrate traces.[3] The beds range in thickness, up to over 100 feet in depth in some areas (such as at White Cliffs).,[4] but thins to the east and is only a few feet thick north of Columbus, Arkansas and is completely missing to the east. The break between the Annona Formation and the Ozan Formation appears to be sharp with a few tubular borings up to a foot long extending down from the Annona in to the Ozan.[5]

Annona Chalk
Stratigraphic range: Cretaceous
Outcrop east of Clarksville, TX (c. 1910)
TypeSedimentary
Sub-unitsAustin Group
UnderliesMarlbrook Marl
OverliesOzan Formation
Thickness30 Meters
Lithology
PrimaryChalk
Location
RegionArkansas
CountryUnited States
Type section
Named forAnnona, Red River County, Texas[1]
Named byRobert Thomas Hill

Exposures

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Paleofauna

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B. crickmayi[6]
B. taylorensis[6]
D. binodosum[6]
D. clardyi[6]
N. (Nostoceras) danei[6]
N. (Nostoceras) monotuberculatum[6]
N. (Nostoceras) plerucostatum[6]
N. (Nostoceras) pulcher[6]
O. crassum[6]
A. ponderosana[7]
B. rotunda[7]
B. ovata[7]
B. windhami[7]
C. austinensis[7]
C. caudata[7]
C. communis[7]
C. filicosta[7]
C. paraustinensis[7]
C. crafti[7]
C. tollettensis[7]
C. blakei[7]
H. bruceclarki[7]
H. globosa[7]
H. micropunctata[7]
H. plummeri[7]
K. cushmani[7]
L. fletcheri[7]
M. montuosa[7]
M. pedata[7]
O. hannai[7]
P. texanus[7]
V. ozanana[7]

See also

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References

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  1. ^ Hill, R.T. (1894). "Geology of parts of Texas, Indian Territory and Arkansas adjacent to Red River". Bulletin of the Geological Society of America. 5: 308.
  2. ^ USGS Geolex, Annona Chalk/Formation
  3. ^ R. T. Hill. "Annona Chalk Formation". Arkansas Geological Survey. Arkansas Geological Survey. p. 308. Archived from the original on May 27, 2010. Retrieved 25 May 2015.
  4. ^ Veatch, Arthur Clifford (1906). Geology and Underground Water Resources of Northern Louisiana and Southern Arkansas. U.S. Government Printing Office.
  5. ^ Dane, 1929, Upper Cretaceous Formations of Southwestern Arkansas, Arkansas Geological Survey Bulletin 1
  6. ^ a b c d e f g h i j k l Kennedy, W. J.; Cobban, W. A. (1993). "Campanian ammonites from the Annona Chalk near Yancy, Arkansas". Journal of Paleontology. 67 (1): 83–97.
  7. ^ a b c d e f g h i j k l m n o p q r s t u v w x y Collins, Jr., Robert J. (June 1960). Stratigraphy and Ostracoda of the Ozan, Annona, and Marlbrook Formations of southwestern Arkansas (PhD). Louisiana State University and Agricultural and Mechanical College.