The BGS Lexicon of Named Rock Units — Result Details
Shaftesbury Sandstone Member
| Computer Code: | SHYS | Preferred Map Code: | Shy |
|---|---|---|---|
| Status Code: | Full | ||
| Age range: | Albian Age (KA) — Albian Age (KA) | ||
| Lithological Description: | The member is an alternating succession of fine- to medium-grained glauconitic sand and sandstone. At the top, a massive, 2 to 3m-thick, shelly calcareous sandstone called the Ragstone is present in some areas. | ||
| Definition of Lower Boundary: | The lower boundary is not usually observed and is probably gradational with an upwards decrease in silt and clay grade material and mica of the underlying Cann Sand Member up into fine- to medium-grained glauconitic, partially cemented sands of the member. In field mapping terms the boundary is a well-marked feature break, presumably coinciding with incoming of cemented sandstone in the overlying Shaftesbury Sandstone. | ||
| Definition of Upper Boundary: | In general the upper boundary is placed at the facies change from indurated, shell-rich sandstone without chert ("Ragstone") of the Shaftesbury Sandstone Member, to less indurated sandstone with regularly developed beds of chert of the Boyne Hollow Chert Member. Where the "Ragstone" is absent the boundary is placed below the lowest chert bed or at a disconformity immediately beneath. The boundary is locally marked by phosphatic nodules in the Shaftesbury (Sheet 313) district, and may also be disconformable thereabouts. In some parts of the Shaftesbury district, the upper boundary is the unconformable contact with the Bookham Conglomerate Bed at the base of the Chalk Group. | ||
| Thickness: | 0 to 25m (3.9m exposed at the type locality, of a total thickness of about 15m). | ||
| Geographical Limits: | Found in Dorset and Wiltshire. Main outcrop from Fontmell Magna [ST 865 170] northwards across the Shaftesbury Sheet (313) and onto the Wincanton Sheet (297) but extends onto the Frome (281), Devizes (282), Wincanton (297), Salisbury (298), Ringwood (314), Bridport (327), Dorchester (328), West Fleet and Weymouth (341 & 342) sheet areas. | ||
| Parent Unit: | Upper Greensand Formation (UGS) | ||
| Previous Name(s): | Ragstone Beds
(-525)
Ragstone [Obsolete Name and Code: Use SHYS] (-1181) Ragstone and Freestone Beds [Obsolete Name and Code: Use SHYS] (-3676) |
||
| Alternative Name(s): | none recorded or not applicable | ||
| Stratotypes: | |||
| Type Section | Old quarry, 110m at 295 degrees from Mayo Farm on northeast side of Boyne Hollow. Face now degraded, but section recorded by Jukes-Browne and Hill, 1900. | ||
| Reference(s): | |||
| Jukes-Browne, A J and Hill, W. 1900. The Cretaceous Rocks of Britain. 1. Gault and Upper Greensand. Memoir of the Geological Survey of Great Britain. | |||
| Drummond, P U O. 1970. The Mid-Dorset Swell. Evidence of Albian-Cenomanian Movements in Wessex. Proceedings of the Geologists' Association, Vol.81, 679-714. | |||
| Bristow, C R. 1989. Geology of the East Stour - Shaftesbury district (Dorset) British Geological Survey Technical Report WA/89/58. | |||
| Bristow, C R. 1991. Geology of Sheet ST 81 (Shillingstone-Compton Abbas, Dorset). British Geological Survey Technical Report WA/91/03. | |||
| White, H J O. 1923. The geology of the country south and west of Shaftesbury. Memoir of the Geological Survey of Great Britain, Sheet 313 (England and Wales). | |||
| Bristow, C R, Barton, C M, Freshney, E C, Wood, C J, Evans, D J, Cox, B M, Ivimey-Cook, H C, and Taylor, R T. 1995. Geology of the country around Shaftesbury. Memoir of the British Geological Survey, Sheet 313 (England and Wales). | |||
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: | |||
| E281 E313 E327 E341 E342 E343 | |||