The BGS Lexicon of Named Rock Units — Result Details
Carstone Formation
| Computer Code: | CA | Preferred Map Code: | Ca |
|---|---|---|---|
| Status Code: | Full | ||
| Age range: | Albian Age (KA) — Albian Age (KA) | ||
| Lithological Description: | The typical lithology of the Carstone Formation is a greenish-brown (rusty when weathered), thick-bedded, cross-bedded, oolitic ferruginous sandstone. The formation is medium- to coarse-grained and pebbly in part, especially at the base where it becomes a conglomerate. Pebbles comprising quartz, quartzite, pyritised sandstone, ironstone, grey siltstone and rolled ammonites. Some beds are silty and/ or contain clay wisps. Glauconite may be present in variable amounts. The Carstone Formation is burrowed in places with common Arenicolites and Skolithus. | ||
| Definition of Lower Boundary: | The Carstone Formation, which was deposited during a phase of unconformable transgression, oversteps many different lithostratigraphical units. Its base is erosional and locally burrowed into the underlying strata. The base can be recognized by a downward change from greenish-brown, thick-bedded, cross-bedded, commonly bioturbated, oolitic, ferruginous, medium- to coarse-grained and pebbly sandstone on (from south to north): Palaeozoic sequences on the London Platform (e.g. Four Ashes Borehole); quartz sands and thin mudstone (Dersington Formation); buff and grey, clayey ferruginous sands and quartz sands (Sandringham Sands Formation) in central Norfolk, between Leziate and West Dereham; pale and medium clays (Kimmeridge Clay Formation) in central Norfolk (Mudford-Great Ellingham); pale-medium grey, very fine- to fine-grained, bioturbated, shelly sandstones with phosphatic nodules (Roach Formation) in Northern Norfolk; Shelly, calcareous mudstone (Sutterby Marl) in southern Lincolnshire; Ironstone (Fulletby Formation) in central Lincolnshire; Dark, glauconitic mudstones and limestones (Tealby Formation) in northern Lincolnshire; brown, shelly oolitic ironstone (Claxby Ironstone Formation); late Jurassic mudstones (Kimmeridge Clay and Ampthill Clay formations) and coarse-grained sandstone (Elsham Sandstone Member) at the Humber Estuary; pale to medium, fine- to medium-grained sandstones and dark mudstones (Kellaways Formation) in southern Yorkshire; Upper Lias mudstones on the south side of the Market Weighton High. | ||
| Definition of Upper Boundary: | In southern and central Norfolk the upper boundary is defined by an up-section transition from greenish-brown, massive, cross-bedded, bioturbated, oolitic ferruginous sandstone to pale to medium grey mudstones and siltstones (Gault Formation). In northern Norfolk and Lincolnshire the boundary is marked by a sharp, perhaps gradational, up-section change from greenish-brown, massive cross-bedded, bioturbated, oolitic, ferruginous sandstone into red, pink or cream limestones and marls (Hunstanton Chalk Formation). | ||
| Thickness: | Generally up to about 5m, but it reaches its maximum thickness, of 18.9m, in the Hunstanton Borehole. | ||
| Geographical Limits: | The southern limit of the formation is between Duxford and Soham, Cambridgeshire, and southeast of the Four Ashes Borehole (TM07SW1 [TM 02230 71860]) on the London Platform High, although it is not seen at outcrop in these areas. The Carstone extends northwards through Norfolk and its best exposure is in the cliffs and foreshore at Hunstanton. North of The Wash, the Carstone Formation is present in Lincolnshire, beneath the Wolds and forming a narrow outcrop along their western margin. In northern Lincolnshire it is thin and locally absent. North of the Humber the Carstone Formation is again thin and patchy, but it has been recorded near South Cave, Goodmanham, Millington and Kirby Underdale, finally disappering on the Market Weighton High. | ||
| Parent Unit: | Not Applicable (-) | ||
| Previous Name(s): | Carstone Grit [Obsolete Name and Code: Use CA]
(-2040)
Carstone Grit of the Langton Series [Obsolete Name and Code: Use CA] (-2659) Langton Series [Obsolete Name and Code: Use CA] (-4511) Lower Carstone [Obsolete Name and Code: Use CA] (-3265) Sand and clay [Obsolete Name and Code: Use CA] (-3891) Thoresway Sand [Obsolete Name and Code: Use CA] (-3892) Upper Carstone [Obsolete Name and Code: Use CA] (-3893) Carstone [Obsolete Name and Code: Use CA] (*749) |
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| Alternative Name(s): | none recorded or not applicable | ||
| Stratotypes: | |||
| Reference Section | Hunstanton Cliff and Foreshore at Hunstanton to St Edmound's Point. The uppr 10m of the Carstone, including its junction with the Hunstanton Formation are well exposed on the cliffs between the Esplanade and St Edmund's Point. (Gallois, 1994) | ||
| Reference Section | Hunstanton Borehole (TF64SE11). "The thickest development of Carstone recorded to date is that proved in the Hunstanton Borehole [6857 4078] between 17.96 and 36.86m" (Gallois, 1994, p.108). | ||
| Reference(s): | |||
| Gallois, R W. 1973. The base of the Carstone at Hunstanton. Bulletin of the Geological Society of Norfolk, Vol.23, 25-34. | |||
| Gallois, R W. 1975. The base of the Carstone at Hunstanton - Part 11. Bulletin of the Geological Society of Norfolk, No.27, 21-27. | |||
| Whitaker, W and Jukes-Browne, A J. 1899. The geology of the borders around The Wash: including Boston and Hunstanton. Memoir of the Geological Survey of England and Wales. | |||
| Gallois, R W. 1984. The Late Jurassic to Mid Cretaceous rocks of Norfolk. Bulletin of the Geological Society of Norfolk, Vol.34, 3-64. | |||
| Gallois, R W and Mortimer, A A. 1982. The stratigraphy of the Gault of East Anglia. Proceedings of the Geologists' Association, Vol.93, 351-368. | |||
| Owen, H G. 1991. Ammonites from the Middle Albian of Heligoland and adjacent regions with some phylogenetic observations. Geologishe Jahrbuch, A120, 289-303. | |||
| Owen, H G. 1995, The upper part of the Carstone and the Hunstanton Red Chalk (Albian) of the Hunstanton Cliff, Norfolk. Proceedings of the Geologists' Association. Vol.106, 171-181. | |||
| Rose, C B. 1862. On the Cretaceous group in Norfolk. Proceedings of the Geologists' Association, Vol.1, 234-236. | |||
| Waters, C N, Smith, K, Hopson, P M, Wilson, D, Bridge, D M, Carney, J N, Cooper, A H, Crofts, R G, Ellison, R A, Mathers, S J, Moorlock, B S P, Scrivener, R C, McMillan, A A, Ambrose, K, Barclay, W J, and Barron, A J M. 2007. Stratigraphical Chart of the United Kingdom: Southern Britain. British Geological Survey, 1 poster. | |||
| 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. | |||
| Gallois, R W, 1994. The geology of the country around King's Lynn and The Wash. Memoir of the British Geological Survey, Sheet 145 and part of 129 (England and Wales). | |||
| Strahan, A. 1886. Notes on the relations of the Lincolnshire Carstone. Quarterly Journal of the Geological Society, London, 42, 481-493. | |||
| Wilkinson, I P. 2006. The Holostratigraphy of the Albian Stage (Lower Cretaceous) of the United Kingdom and its continental shelf. British Geological Survey Research Report, RR/06/01. | |||
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: | |||
| E103 E115 E129 E132 E145 E146 E148 E160 E161 E162 E173 E175 E176 E055 E065 E080 E081 E089 E090 E091 | |||