Annona Chalk
| Annona Chalk Stratigraphic range: Cretaceous | |
|---|---|
 Outcrop east of Clarksville, TX (c. 1910) | |
| Type | Formation |
| Sub-units | Austin Group |
| Underlies | Ozan Formation |
| Overlies | Brownstown Marl |
| Thickness | 30 Meters |
| Lithology | |
| Primary | Chalk |
| Location | |
| Region | Arkansas |
| Country | United States |
| Type section | |
| Named for | Annona, TX |
Annona Chalk overlying Brownstown Marl at White Cliff, Howard County, AR (c. 1910)
The Annona Chalk is a geologic formation in Arkansas, Texas, Louisiana, and Oklahoma.[1] 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.[2] The beds range in thickness, up to over 100 feet in depth in some areas (such as the White Cliffs).[3] There is a gradual transition between the Annona chalk and the underlying Brownstown formation, where chalk and marl are interbedded.[4]
See also
References
- ↑ USGS Geolex, Annona Chalk/Formation
- ↑ R. T. Hill. "ANNONA CHALK/FORMATION". Arkansas Geological Survey. v. 5: Arkansas Geological Survey. p. 308. Retrieved 25 May 2015.
- ↑ Veatch, Arthur Clifford (1906). Geology and Underground Water Resources of Northern Louisiana and Southern Arkansas. U.S. Government Printing Office.
- ↑ Matson, G. C., 1916, The Caddo Oil and Gas Field, Louisiana and Texas, USGS Bulletin 619
- Various Contributors to the Paleobiology Database. "Fossilworks: Gateway to the Paleobiology Database". Retrieved 8 July 2014.
- Notes on the Annona Chalk, Norman L. Thomas and Elmer M. Rice, Journal of Paleontology, Vol. 6, No. 4 (Dec., 1932), pp. 319-329
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