The BGS Lexicon of Named Rock Units — Result Details

Kellaways Formation

Computer Code: KLB Preferred Map Code: Kys
Status Code: Full
Age range: Callovian Age (JC) — Callovian Age (JC)
Lithological Description: Mudstone, grey, commonly silici-silty or silici-sandy, with (predominantly in the upper part) beds of generally calcareous siltstone and sandstone.
Definition of Lower Boundary: Generally sharp, conformable or non-sequential junction with bioclastic limestone of underlying Cornbrash Formation, overlain by grey mudstone, commonly a thin unit of shell-fragmental, more or less sandy mudstone occurs at base (where this is more strongly cemented it is included in the Cornbrash Formation).
Definition of Upper Boundary: Generally sharp but conformable junction between sandstone/siltstone in upper part of formation with mudstone of overlying Oxford Clay Formation; in expanding successions, (Wessex Basin), arbitrary boundary drawn at the top of the highest substantial sandstone or sandy mudstone, above which the succession is predominantly mudstone; in the Market Weighton area, sharp disconformable contact with chalky argillaceous sediments of the Chalk Group/Hunstanton Formation.
Thickness: 0 to perhaps (in south Dorset) 50m; typically c.20m in the Wessex Basin, and c.5 to 8m on the East Midlands Shelf.
Geographical Limits: Dorset coast (Weymouth area) to Malton area, Yorkshire (just north of the Market Weighton High). Extensive in onshore subcrop, though absent over the interior of the London Platform.
Parent Unit: Ancholme Group (AMG)
Previous Name(s): Kellaways Beds Formation (-996)
Kellaways Rock Plus Kellaways Clay (-4730)
Kellaways Formation Plus Cayton Clay Formation (-2266)
Kellaways Beds (-347)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Area  Kellaways, near Chippenham, Wiltshire. 
Reference Section  BGS Walks Farm Borehole, 2.5km northnortheast of Heckington, near Sleaford, Lincolnshire. TF14 NE/18. 91.60 to 98.37m depth. Berridge et al., 1999 and manuscript log of borehole TF/4NE/18 in BGS Archive. 
Reference Section  'Fault Corner', Grange Top Quarry, Ketton, Rutland. Fully exposed, 8.50m thick (Hudson and Clements, 2007, 258-259) 
Type Section  BGS Tytherton No.3 Borehole, 2.7km eastnortheast of Chippenham, Wiltshire. ST 97SW/2, 3.35 to 24.27m depth. Top of formation not seen. Cave and Cox, 1975. 
Reference(s):
Smith, W. 1817. Strata identified by organized fossils, Part 3. [London.] 
Gaunt, G D, Fletcher, T P and Wood, C J. 1992. Geology of the country around Kingston upon Hull and Brigg. Memoir of the British Geological Survey, sheets 80 and 89 (England and Wales). 172pp. 
Hudson, J D and Clements, R G. 2007. The Middle Jurassic Succession at Ketton, Rutland. Proceedings of the Geologists' Association, Vol 118, 239-264. 
Cave, R and Cox, B M. 1975. The Kellaways Beds of the area between Chippenham and Malmesbury, Wiltshire. Bulletin of the Geological Survey of Great Britain, No.54, 41-46. 
Judd, J W. 1875. The geology of Rutland and parts of Lincoln, Leicester, Northampton, Huntingdon and Cambridge. Memoir of the Geological Survey of Great Britain (Old Series sheet 64). 
Arkell W J, 1933. The Jurassic System in Great Britain [Oxford: Clarendon Press.] 
Berridge, N G, Pattison, J, Samuel, M D A, Brandon, A, Howard, A S, Pharaoh, T C and Riley, N J. 1999. Geology of the Grantham district. Memoir of the British Geological Survey, sheet 127 (England and Wales). 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E102 E114 E127 E159 E171 E172 E187 E188 E202 E203 E204 E217 E218 E219 E220 E236 E237 E253 E266 E268 E281 E327 E341 E342 E343 E064 E072 E080 E081 E089