Annona Chalk
| Annona Chalk Stratigraphic range: Cretaceous | |
|---|---|
 Outcrop east of Clarksville, TX (c. 1910) | |
| Type | Formation |
| Sub-units | Austin Group |
| Underlies | Ozan Formation, Marlbrook Marl |
| Overlies | Brownstown Marl, Ozan Formation |
| Thickness | 30 Meters |
| Lithology | |
| Primary | Chalk |
| Location | |
| Region | Arkansas |
| Country | United States |
| Type section | |
| Named for | Annona, Red River County, Texas[1] |
| Named by | Robert Thomas Hill |
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 the White Cliffs).[4] There is a gradual transition between the Annona chalk and the underlying Brownstown formation, where chalk and marl are interbedded.[5]
Exposures
Annona Chalk overlying Brownstown Marl at what is now called White Cliffs Natural Area, with the Little River in the foreground, Howard County, AR (c. 1910)
Another view of the same location (c. 1902)
Quarry at Whitecliffs Landing (c. 1902)
See also
References
- ↑ 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.
- ↑ 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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