The BGS Lexicon of Named Rock Units — Result Details
Harrath Tuff Member
Computer Code: | HHT | Preferred Map Code: | HhT |
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Status Code: | Full | ||
Age range: | Caradoc Series (O4) — Caradoc Series (O4) | ||
Lithological Description: | Rhyolitic tuff - densely welded, foliated, white-weathered. | ||
Definition of Lower Boundary: | Base of rhyolitic tuff that rests on an erosion surface cut in dacitic lapilli-tuff of the Waberthwaite Formation; basaltic andesite intrusions may intervene. | ||
Definition of Upper Boundary: | Top of rhyolitic tuff - probably an erosion surface at contact with overlying dacitic lapilli-tuff of the Waberthwaite Formation. | ||
Thickness: | 60 to c.250m | ||
Geographical Limits: | Between Harrath (hill) and Corner Croft, north of The Hill, near Millom, Cumbria. | ||
Parent Unit: | Waberthwaite Tuff Formation (WB) | ||
Previous Name(s): | Rhyolitic Series [Obsolete Name and Code: Use HHT]
(-4093)
Harrath Tuffs and Lavas [Obsolete Name and Code: Use BWT, HHT] (-3886) |
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Alternative Name(s): | none recorded or not applicable | ||
Stratotypes: | |||
Type Area | Between Harrath (hill) and Corner Croft north of The Hill near Millom, Cumbria. | ||
Reference(s): | |||
Green, J F N, 1913. The older Palaeozoic succession of the Dudden Estuary. London, 23pp. | |||
Mathieson, N A, 1986 Geology, structure and geochemistry of the Ordovician volcanic succession in south west Cumbria. Unpublished Ph.D. thesis, University of Sheffield. | |||
Johnson, E W, Soper, N J, Burgess, I C, Ball, D F, Beddoe-Stephens, B, Carruthers, R M, Fortey, N J, Hirons, S, Merritt, J W, Millward, D, Roberts, B, Walker, A B and Young, B. 2001. Geology of the country around Ulverston. Memoir of the British Geological Survey, England and Wales, Sheet 48. | |||
1:50K maps on which the lithostratigraphical unit is found, and map code used: | |||
E048 |