The BGS Lexicon of Named Rock Units — Result Details
Bulkeley Hill Sandstone Formation [Obsolete: use HEY]
| Computer Code: | BHSF | Preferred Map Code: | notEntered |
|---|---|---|---|
| Status Code: | Index Level | ||
| Age range: | Early Triassic Epoch (TE) — Early Triassic Epoch (TE) | ||
| Lithological Description: | [Obsolete: use HEY] Sandstone, red, medium-grained with well-rounded "millet seed" grains, cross-stratified, interbedded with mudstone, red-brown and grey-green, and sandstone, brown, fine-grained, flaggy, micaceous. | ||
| Definition of Lower Boundary: | Conformable, within a gradational, interdigitating transition from the red, fine- to medium-grained sandstones of the Wilmslow Sandstone Formation to the interbedded red and green mudstone, brown flaggy sandstone and red-brown cross-stratified sandstone of the Bulkeley Hill Sandstone Formation. | ||
| Definition of Upper Boundary: | Unconformable, at the abrupt upward transition from the interbedded red and green mudstone, brown flaggy sandstone and red-brown cross-stratified sandstone of the Bulkeley Hill Sandstone Formation to deep red and grey mottled, coarse-grained pebbly sandstone at the base of the Helsby Sandstone Formation. | ||
| Thickness: | Up to 22 m at outcrop in the Bulkeley area, Cheshire (Poole and Whiteman, 1966), may reach up to 200 m in the subsurface to the east, based on seismic evidence (Evans et al., 1993). | ||
| Geographical Limits: | Crops out at surface in the Bulkeley area, south Cheshire. Westwards, the formation is cut out beneath the erosional base of the overlying Helsby Sandstone Formation (Poole and Whiteman, 1966). In the subsurface to the east (Prees area), the formation is most fully developed in the hanging wall of the fault zone marking the eastern boundary of the Cheshire Basin, where seismic evidence (Evans et al., 1993) indicates a thickness of over 200 m. | ||
| Parent Unit: | none recorded or not applicable | ||
| Previous Name(s): | Keuper Sandstone Passage Beds [Obsolete name use HEY]
(-56)
Bulkeley Hill Formation [Obsolete Name and Code: Use BHSF] (-4463) |
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| Alternative Name(s): | none recorded or not applicable | ||
| Stratotypes: | |||
| Type Area | Bulkeley Hill, Cheshire. Poole and Whiteman, 1966. | ||
| Reference(s): | |||
| Warrington, G, Audley-Charles, M G, Elliott, R E, Evans, W B, Ivimey-Cook, H C, Kent, P E, Robinson, P L, Shotton, F W and Taylor, F M. 1980. A correlation of the Triassic rocks in the British Isles. Special Report of the Geological Society of London, No.13. | |||
| Poole, E G, and Whiteman, A J. 1966. Geology of the country around Nantwich and Whitchurch. Memoir of the Geological Survey of Great Britain, Sheet 122 (England and Wales). | |||
| Rees, J G and Wilson, A A. 1998. Geology of the country around Stoke-on-Trent. Memoir of the British Geological Survey, Sheet 123 (England and Wales). | |||
| Evans, D J, Rees, J G and Holloway, S. 1993. The Permian to Jurassic stratigraphy and structural evolution of the central Cheshire Basin. Journal of the Geological Society of London, Vol.150, 857-870. | |||
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: | |||
| none recorded or not applicable | |||