The BGS Lexicon of Named Rock Units — Result Details

Fuller's Earth Formation
Computer Code: FE Preferred Map Code: FE
Status Code: Full
Age range: Bathonian Age (JN) — Bathonian Age (JN)
Lithological Description: Silicate-mudstone, grey, bedded, variably calcareous, grading to lime-mudstone, fossiliferous, with units of thinly interbedded, more or less silici-muddy limestone (including the Fuller's Earth Rock Member, Dodington Ash Rock Member), and well-bedded sandy limestone and calcareous sandstone (including the Eyford Member and Througham Member). Where the Fuller's Earth Rock Member is present, the mudstone beds below and above are termed the Lower Fuller's Earth Member and Upper Fuller's Earth Member respectively, and parts of these may be given local names (see separate entries). The commercial fuller's earth bed occurs in the upper part of the formation in the Bath area. In the English Channel Basin the formation is predominantly mudstone with carbonaceous material at some levels and shell beds. In the St George's Channel Basin it is predominantly mudstone but includes calcareous sandstone beds.
Definition of Lower Boundary: In the northeast Cotswolds, passage up from fine- to medium-grained ooid-grainstone of the Chipping Norton Limestone Formation (Great Oolite Group) into silicate-mudstone, or (Cotswolds to the English Channel) generally sharp, commonly non-sequential, junction between predominantly coarse-grained peloidal, ooidal and shell-fragmental limestones or (St George's Channel) calcareous sandstone of the Inferior Oolite Group overlain by silicate-mudstone.
Definition of Upper Boundary: Generally sharp, commonly non-sequential, junction between variably calcareous silicate-mudstone, and limestones of overlying parts of Great Oolite Group: including (from Bath south to Dorset and in the English Channel) fossiliferous limestones of the Wattonensis Beds of the Frome Clay Formation, and (northeast of Bath) ooidal and shell-fragmental limestones, including the Chalfield Oolite Formation, Athelstan Oolite Formation, Taynton Limestone Formation, or fine-grained limestone of the Tresham Rock Formation.
Thickness: 5 to over 260m (thickest in the Wessex Basin area). Offshore: generally over 100 to 300m in the English Channel (Hamblin et al., 1992) (Barton et al., 2008), up to 300m in the Celtic Sea-St George's Channel (Tappin et al., 1994).
Geographical Limits: Onshore: Dorset coast to the Burford area, Oxfordshire. Through the mid Cotswolds, the Upper Fuller's Earth passes north into various limestone formations (see e.g. Wyatt, 1996). In subcrop, widespread in the Wessex Basin. Offshore: English Channel - Celtic Sea - St George's Channel basins.
Parent Unit: Great Oolite Group (GOG)
Previous Name(s): Fuller's Earth (-2180)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Area  Bath, Somerset (William Smith, 1799, unpublished; see Arkell, 1933; Penn and Wyatt, 1979). 
Type Section  Horsecombe Vale No.15 Borehole, Bath. ST76SE/24. 7.62 to 53.45m depth. Dominated by mudstone, and includes the fuller's earth bed. Resting on the hardground top of the Inferior Oolite Group (here the informal Doulting Beds). Sharp top with encrusting oysters overlain by the Chalfield Oolite Formation. (Penn et al., 1979). 
Reference Section  Stowell Park Borehole; SP01SE/1. 32.79 to 49.02m depth, including the Eyford Member 32.79 to 34.62m. Sharp, irregular base on burrowed top of ooidal limestone of the Salperton Limestone Formation (Inferior Oolite Group). Overlain by white ooid-limestone of the Taynton Limestone Formation (Green and Melville, 1951; Sumbler, Barron and Morigi, 2000a, b). 
Reference Section  BGS Purse Caundle Borehole ST71NW/7, near Sherborne, Dorset. 12.48 to 89.99m depth. Dominated by mudstone, with subordinate limestone. Subdivided into three members: Lower Fuller's Earth, Fuller's Earth Rock and Upper Fuller's Earth which are further divided into named units. Passes up from silici-muddy limestone of Inferior Oolite Group (here the informal Crackment Limestones). Passes up into calcareous mudstone of Wattonensis Beds (Frome Clay Formation) Samples held by BGS.(Barton et al., 1993)(Bristow et al., 1995). 
Reference Section  Winterborne Kingston Borehole SY89NW/1 793.00 to 906.06m depth. Mudstone-dominated and includes the Fuller's Earth Rock. Overlies Inferior Oolite Group limestone, and underlies the Wattonensis Beds of the Frome Clay Formation (Penn, 1982)(Barton et al., 2008). 
Reference(s):
Cope, J C W (Editor). 1980. A correlation of Jurassic rocks in the British Isles. Part Two: Middle and Upper Jurassic. Geological Society of London Special Report, No.15. 
Penn, I E. 1982. Middle Jurassic stratigraphy and correlation of the Winterborne Kingston Borehole, Dorset. 53-76 in Rhys, G H, Lott, G K and Calver, M A (editors), The Winterborne Kingston Borehole, Dorset, England. Report of the Institute of Geological Sciences, No.81/3. 
Sumbler, M G, Barron, A J M and Morigi, A N. 2000. Reply to Wyatt, R J. 2000. Correlation of the Bathonian (Middle Jurassic) succession in the Minchinhampton-Burford district. Proceedings of the Geologists' Association, Vol. 111, 189. 
Barton, C M, Woods, M A, Bristow, C R, Newell, A J, Westhead, R K, Evans, D J, Kirby, G A, and Warrington, G. 2008. Geology of south Dorset and south-east Devon and its World Heritage Coast. British Geological Survey Special Memoir. 
Tappin, D R, Chadwick, R A, Jackson, A A, Wingfield, R T R and Smith, N J P. 1994. The geology of Cardigan Bay and the Bristol Channel. British Geological Survey Memoir. 
Green, G W and Melville, R V. 1956. The stratigraphy of the Stowell Park Borehole (1949-51). Bulletin of the Geological Survey of Great Britain, Vol. 11, 1-66. 
Arkell, W J. 1933. The Jurassic System in Great Britain. (Oxford: Clarendon Press.) 
Barton, C M, Ivimey-Cook, H C, Lott, G K and Taylor, R T. 1993. The Purse Caundle Borehole, Dorset: stratigraphy and sedimentology of the Inferior Oolite and Fuller's Earth in the Sherborne area of the Wessex Basin. British Geological Survey Research Report No.SA/92/01. 
Bristow, C R, Barton, C M and Freshney, E C, et al. 1995. The geology of the country around Shaftesbury. Memoir of the British Geological Survey, Sheet 313 (England and Wales). 
Penn, I E, Merriman, R J and Wyatt, R J. 1979. A proposed Type section for the Fuller's Earth (Bathonian) based on the Horsecombe Vale No.15 Borehole, near Bath, with details of contiguous strata. The stratigraphy and correlation of the Bathonian strata of the Bath-Frome area. Report of the Institute of Geological Sciences, No.78/22, 3-22. 
Penn, I E and Wyatt, R J. 1979. The stratigraphy and correlation of the Bathonian strata of the Bath-Frome area. Report of the Institute of Geological Sciences, No.78/22, 23-88. 
Wyatt, R J. 1996. A correlation of the Bathonian (Middle Jurassic) succession between Bath and Burford, and its relation to that near Oxford. Proceedings of the Geologists' Association, Vol.107, 299-322. 
Hamblin, R J O, Crosby, A, Balson, P S, Jones, S M, Chadwick, R A, Penn, I E and Arthur, M J. 1992. The geology of the English Channel. British Geological Survey Memoir. 
Sumbler, M G, Barron, A J M and Morigi, A N. 2000. Geology of the Cirencester district. Memoir of the British Geological Survey, Sheet 235 (England and Wales). 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E217 E234 E235 E236 E265 E281 E297 E313 E341 E342 E343 E252 E251 E312 E327
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