The BGS Lexicon of Named Rock Units — Result Details
Long Top Tuff Member
Computer Code: | LTT | Preferred Map Code: | LTT |
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Status Code: | Full | ||
Age range: | Caradoc Series (O4) — Caradoc Series (O4) | ||
Lithological Description: | Bedded units of massive, eutaxitic rhyolitic tuff and lapilli-tuff. Intercalations of bedded and laminated tuff widespread. Localized units of pyroclastic breccia. | ||
Definition of Lower Boundary: | Base of rhyolitic pyroclastic rocks. Unconformable, on slumped surface of Whorneyside Tuff Formation and locally on the underlying Birker Fell Andesite Formation, but locally interbedded. | ||
Definition of Upper Boundary: | Defined by the bases of overlying Crinkle Tuff Member of the Airy's Bridge Tuff Formation. | ||
Thickness: | 0 - 310m | ||
Geographical Limits: | Crinkle Crags and Scafell area, extending to Coniston Fells, Duddon Valley, Eskdale, Wasdale, Borrowdale and Langdale. | ||
Parent Unit: | Airy's Bridge Tuff Formation (AIB) | ||
Previous Name(s): | Long Top Member [Obsolete Name and Code: Use LTT]
(-2303)
Long Top Tuffs [Obsolete Name and Code: Use LTT] (-2304) |
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Alternative Name(s): | none recorded or not applicable | ||
Stratotypes: | |||
Type Area | Long Top, Crinkle Crags. | ||
Reference(s): | |||
Oliver, R L, 1961. The Borrowdale Volcanic and associated rocks of the Scafell area, English Lake District. Quarterly Journal of the Geological Society of London, Vol 117, p. 377-417 | |||
Branney, M J, Davis, N C, Kokalaar, B P and McConnell, B J. 1993. The Airy's Bridge Formation in the central Fells. British Geological Survey Technical Report WA/93/41 | |||
1:50K maps on which the lithostratigraphical unit is found, and map code used: | |||
E038 E029 |