The BGS Lexicon of Named Rock Units — Result Details

Tongue House Member [Obsolete Name: Replaced By LIT, GWD, GY]

Computer Code: TNM Preferred Map Code: TNM
Status Code: Index Level
Age range: Caradoc Series (O4) — Caradoc Series (O4)
Lithological Description: Dacitic ignimbrites and lava contains three defined beds - in ascending order these are the Little Stand Tuff, Great Whinscale Dacite and the Grey Friar Tuff; in places bedded tuffs and other laterally impersistent andesitic ignimbrites separate these named beds.
Definition of Lower Boundary: Defined at base of thin-bedded tuffs underlying the nodular rhyolitic ignimbrite (Little Stand Tuff).
Definition of Upper Boundary: Top defined by overlying bedded tuffs on porphyritic andesite sheets.
Thickness: 200 metres in type section; lateral variations 85-200m; absent north of Hard Knott-Stonesty Gill.
Geographical Limits: Not defined.
Parent Unit: Birker Fell Andesite Formation (BFA)
Previous Name(s): Great Whinscale Member [Obsolete Name And Code: See TNM] (GWM)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Area  Tongue House, High Close, Sheet 38 (Ambleside). 
Reference(s):
Millward, D, Johnson, E W, Mathieson, N A, Branney, M, Beddoe-Stephens, B and Allen, P M. Not yet published. A revision of the lithostratigraphy of the Borrowdale Volcanic Group in the south-western part of the English Lake District, and on 1:10,000 maps SD19NE and 19NW. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E038