The BGS Lexicon of Named Rock Units — Result Details
Beacon Limestone Formation
| Computer Code: | BNLS | Preferred Map Code: | BnL |
|---|---|---|---|
| Status Code: | Full | ||
| Age range: | Pliensbachian Age (JE) — Toarcian Age (JT) | ||
| Lithological Description: | Limestone, ferruginous-ooidal in lower part, nodular in upper part; conglomeratic in parts; variably grey, pink, reddish-brown and brown in colour. Includes Eype Mouth Limestone Member (above) and Marlstone Member (below). | ||
| Definition of Lower Boundary: | Non-sequential; downward change from ferruginous, conglomeratic limestone to argillaceous, silty or sandy beds of the Dyrham Formation. | ||
| Definition of Upper Boundary: | Base of sands of the Bridport Sand Formation. | ||
| Thickness: | Up to 5m; typically less than 1.5m | ||
| Geographical Limits: | Wessex Basin (including Central Somerset Basin) and Mendips-Radstock Shelf area, ie. Dorset coast to approximately Chipping Sodbury. | ||
| Parent Unit: | Lias Group (LI) | ||
| Previous Name(s): | Watton Bed [Obsolete Name and Code: Use BNLS]
(-1370)
Junction Bed [Obsolete Name And Code: Use BNLS] (JB) Junction Bed and Marlstone [Rock Bed] [Obsolete Name and Code: Use BNLS] (-2629) |
||
| Alternative Name(s): | none recorded or not applicable | ||
| Stratotypes: | |||
| Type Area | Dorset and east Somerset. | ||
| Type Section | Cliff exposure beneath Thorncombe Beacon (Callomon and Cope, 1995; Hesselbo and Jenkyns, 1995). | ||
| Reference Section | British Geological Survey Winterborne Kingston Borehole, Winterborne Kingston, Dorset (SY89NW/1) 1114.60-1117.89 m depth (Ivimey-Cook, 1982; Rhys, Lott and Calver, 1982; see also Cox et al., 1999 for additional reference sections). | ||
| Reference(s): | |||
| Callomon, J H and Cope, J C W. 1995. The Jurassic geology of Dorset. 51-103 in Taylor, P D (Editor), Field Geology of the British Jurassic. (Bath: The Geological Society.) | |||
| Waters, C N, Smith, K, Hopson, P M, Wilson, D, Bridge, D M, Carney, J N, Cooper, A H, Crofts, R G, Ellison, R A, Mathers, S J, Moorlock, B S P, Scrivener, R C, McMillan, A A, Ambrose, K, Barclay, W J, and Barron, A J M. 2007. Stratigraphical Chart of the United Kingdom: Southern Britain. British Geological Survey, 1 poster. | |||
| Rhys, G H, Lott, G K, and Calver, M A. 1982. The Winterborne Kingston borehole, Dorset, England. Report of the Institute of Geological Sciences, No.81/3. | |||
| Cox, B M, Sumbler, M G, and Ivimey-Cook, H C. 1999. A Formational framework for the Lower Jurassic of England and Wales (Onshore Area). British Geological Survey Research Report No. RR/99/01. | |||
| Hesselbo, S P and Jenkyns, H C A, 1995. A comparison of the Hettangian to Bajocian successions of Dorset and Yorkshire. 105-150 in Taylor, P D (Editor). Field geology of the British Jurassic (London Geological Society). | |||
| Ivimey-Cook, H C, 1982. Biostratigraphy of the Lower Jurassic and Upper Triassic (Rhaetian rocks of the Winterborne Kingston borehole, Dorset). Report of the Institute of Geological Sciences, No.81/3, 97-106. | |||
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: | |||
| E311 E327 E264 E265 E281 E341 E342 E343 | |||