The BGS Lexicon of Named Rock Units — Result Details

Bridport Sand Formation
Computer Code: BDS Preferred Map Code: BdS
Status Code: Full
Age range: Toarcian Age (JT) — Toarcian Age (JT)
Lithological Description: Grey, weathering yellow or brown, micaceous silt, very fine-grained sand and fine-grained sand, locally with calcite-cemented sandstone beds and lenses, variably sandy clay/mudstone at base, including Downcliff Clay [Member] of type area (Knox, R W O'B, Morton, A C and Lott, G K, 1982; Hesselbo, S P and Jenkyns, H C, 1995, and references therein).
Definition of Lower Boundary: Base of sand/silt or mudstone, as described in the Lithological Description, resting non-sequentially on limestone of the Beacon Limestone Formation or, north of c.Chipping Sodbury area in the Worcester Basin, a gradational boundary with mudstone of the Whitby Mudstone Formation (q.v.)
Definition of Upper Boundary: Non sequential; base of lowest limestone (commonly sandy) of the Inferior Oolite Group resting on sand/silt or mudstone (as in the Lithological Description), or on "[Cotswold] Cephalopod Bed" (sandy and argillaceous, ironshot commonly fossiliferous limestone) in the Worcester Basin area.
Thickness: To c.120m
Geographical Limits: Wessex Basin to Worcester Basin (Dorset Coast to central Cotswolds, Cheltenham area).
Parent Unit: Lias Group (LI)
Previous Name(s): Cotswold Sands (-3200)
Bridport And Yeovil Sands (-1975)
Midford Sand(S) (-680)
Upper Lias Sands (-681)
Yeovil Sands (-682)
Bridport Sands (-1339)
Cotteswold Sands (-3832)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Area  Broadwindsor to Burton Bradstock, Dorset. Wilson, V, et al, 1958. 
Type Section  Coastal cliff exposures (East Cliff and Burton Cliff) between West Bay and Burton Bradstock, Dorset. Callomon, J H and Cope, J C W, 1995; Hesselbo, S P and Jenkyns, H C, 1995. 
Reference Section  British Geological Survey Winterborne Kingston Borehole, Winterborne Kingston, Dorset (SY89NW/1) 927.89-1114.60m depth. Ivimey-Cook, H C, 1982; Knox, R W O'B, Morton, A C and Lott, G K, 1982; Rhys, G H, Lott, G K and Calver, M A, 1982. See also Cox, B M, et al, (1999) for additional reference sections. 
Reference(s):
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. 
Knox, R W O'B, Morton, A C and Lott, G K, 1982. Petrology of the Bridport Sands in the Winterborne Kingston borehole, Dorset. Report of the Institute of Geological Sciences, No.81/3, 107-121. 
Rhys, G H, Lott, G K and Calver, M A (editors), 1982. The Winterborne Kingston borehole, Dorset, England. Report of the Institute of Geological Sciences, No.81/3. 
Wilson, V, et al, 1957. Geology of the country around Bridport and Yeovil. Memoir of the Geological Survey of Great Britian, Sheets 327 and 312. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E234 E235 E251 E265 E281 E297 E312 E327 E217 E252 E280 E341 E342 E343 E264
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