The BGS Lexicon of Named Rock Units — Result Details
Oreton Limestone Formation
| Computer Code: | ORTL | Preferred Map Code: | Ort |
|---|---|---|---|
| Status Code: | Full | ||
| Age range: | Tournaisian Age (CT) — Tournaisian Age (CT) | ||
| Lithological Description: | The lower part is dominated by hard grey crystalline Limestones, crinoidal limestones and ooidal limestones. The upper part of the succession comprises mudstone with thin nodular limestones. | ||
| Definition of Lower Boundary: | The base of the lowermost ooidal or crinoidal limestone-dominated sequence of the Oreton Limestone Formation, underlain conformably by calcareous mudstone and impure limestone of the Avon group in the southern crop near Cleehill [SO 571 750]. This boundary has not been mapped on the Ludlow (181) Sheet. In the north crop near Oreton [SO 665 806]] , the Oreton Likestone Formation is shown resting directly upon conglomeratic sandstone, interpreted to be the basal unit of the Avon Group. | ||
| Definition of Upper Boundary: | Mudstone and nodular limestones of the Oreton Limestone Formation are overlain with an angular unconformity by quartzitic sandstone of the Cornbrook Sandstone Formation. | ||
| Thickness: | About 45 m thick in the northern outcrop between Oreton and Farlow [SO 646 803], and 20 m thick in the southern crop at Clee Hill [SO 571 750]. | ||
| Geographical Limits: | Clee Hills Outlier, between Cleehill [SO 571 750] and Oreton [SO 665 806]. | ||
| Parent Unit: | Pembroke Limestone Group (PEMB) | ||
| Previous Name(s): | Main Limestone
(ML)
Oreton Limestone [Obsolete Name and Code: Use ORTL] (-2354) Main Limestone (ML) |
||
| Alternative Name(s): | none recorded or not applicable | ||
| Stratotypes: | |||
| Partial Type Section | Two quarries at Oreton, about 250 m NE of the New Inn. The western quarry [SO 6519 8068] comprises 11.5 m ofmainly ooidal limestone; the eastern one [SO 6518 8062] comprises 10-11 m of ooidal limestone. Neither base nor the top of the formation are seen. Greig et al., 1968 | ||
| Reference(s): | |||
| Greig D C, Wright, J E, Hains, B A and Mitchell, G H. 1968. Geology of the country around Church Stretton, Craven Arms, Wenlock Edge and Brown Clee. Memoir of the Geological Survey, Sheet 166 (England and Wales). (London: H.M.S.O.). 379pp. | |||
| George, T N. 1956. The Namurian Usk Anticline, Proceedings of the Geologists' Association, Vol.66, 297-316. | |||
| George, T N, Johnson, G A L, Mitchell, M, Prentice, J E, Ramsbottam, W H C, Sevastopulo, G D and Wilson, R B. 1976. A correlation of the Dinantian rocks of the British Isles. Special Report of the Geological Society of London, No 7. | |||
| Dixon, E E L. 1917. The geology of the Titterstone Clee Coal Field. Transactions of the Royal Society of Edinburgh, Vol.51, 1064-1071. | |||
| Turner, N and Spinner, E. 1988. A palynological study of Lower Carboniferous strata (Dinantian), from Titterstone Clee, Shropshire, England. Pollen et Spores, Vol. 30, 429-459. | |||
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: | |||
| E166 E181 | |||