The BGS Lexicon of Named Rock Units — Result Details
Seaham Formation
| Computer Code: | SEH | Preferred Map Code: | notEntered |
|---|---|---|---|
| Status Code: | Full | ||
| Age range: | Guadalupian Epoch (PUG) — Lopingian Epoch (PUL) | ||
| Lithological Description: | Predominantly thin-bedded limestone (calcite mudstone/wackestone with some interbedded coquina, packstone, grainstone, mudstone and concretionary limestone) with some dolostone. | ||
| Definition of Lower Boundary: | Sharp, conformable contact with the underlying Fordon Evaporite Formation (gypsum, anhydrite and halite) offshore and the laterally equivalent Seaham Residue and Edlington Formation onshore. Marked by the incoming of thinly bedded limestone above evaporite and laterally equivalent mudstone | ||
| Definition of Upper Boundary: | The base of the overlying Billingham Anhydrite Formation, or where the latter has been dissolved, at the base of the overlying mudstones and siltstones of the Roxby Formation. | ||
| Thickness: | 1 to 31.5m. | ||
| Geographical Limits: | Durham Province of the English Zechstein: County Durham, Tyne and Wear, Cleveland and northernmost North Yorkshire (equivalent to the Brotherton Formation in the Yorkshire Province). | ||
| Parent Unit: | Zechstein Group (ZG) | ||
| Previous Name(s): | Upper Magnesian Limestone [Obsolete Name and Code: Use SEH, ROD, CNCL]
(-2105)
Concretionary Limestone [Obsolete Name and Code: Use ROD, SEH] (-498) Seaham Beds [Obsolete Name and Code: Use SEH] (-1173) |
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| Alternative Name(s): | Brotherton Formation |
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| Stratotypes: | |||
| Type Area | Dock walls at Seaham Harbour, County Durham (Smith, 1970, 1994). | ||
| Reference(s): | |||
| Smith, D B, 1995. Marine Permian of England. Geological Conservation Review Series No. 8. [London: Chapman and Hall.] | |||
| Smith, D B, Brunstrom, R G W, Manning, D I, Simpson, S and Shotton, F W. 1974. A correlation of Permian rocks in the British Isles. Geological Society of London Special Report No. 5. | |||
| Smith, D B. 1971. The stratigraphy of the Upper Magnesian Limestone in Durham - a revision based on the Institute's Seaham Borehole. Report of the Institute of Geological Sciences, No.71/3. | |||
| Smith, D B, Harwood, G M, Pattison, J and Pettigrew, T H. 1986. A revised nomenclature for Upper Permian strata in eastern England. 9-17 in Harwood, G M and Smith, D B (editors). The English Zechstein and Related Topics. Geological Society Special Publication No.22. | |||
| Smith, D B, 1994. Geology of the country around Sunderland. Memoir of the British Geological Survey, Sheet 21, (England and Wales). | |||
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: | |||
| E021 E027 E032 E033 | |||