The BGS Lexicon of Named Rock Units — Result Details

Cringate Volcaniclastic Member

Computer Code: CRNV Preferred Map Code: notEntered
Status Code: Full
Age range: Arundian Substage (CJ) — Asbian Substage (CR)
Lithological Description: The Cringate Volcaniclastic Member consists of variably stratified volcaniclastic sedimentary rocks and/or tuffs. An exposure in the north-east bank of the Endrick Water at [NS 6800 8750] shows poorly stratified dull red tuff or volcaniclastic sedimentary rock with persistent beds of red mudstone, interspersed with lenticular masses, up to 1.5 m thick, of unsorted lava fragments set in a matrix of greenish clay. Some fragments are scoriaceous with small irregular amygdales filled with chlorite or carbonate minerals. The matrix includes carbonate minerals but also contains some grains of quartz and feldspar.
Definition of Lower Boundary: Seen only in the Endrick Water at [NS 6807 8742], where the Cringate Volcaniclastic Member overlies highly decomposed microporphyritic basalt, thought to be roughly equivalent to middle parts of the Spout of Ballochleam Lava Member (Francis et al., 1970).
Definition of Upper Boundary: Seen only in a left-bank tributary of the Endrick Water at [NS 6858 8756], where about 40 m of tuff or volcaniclastic sedimentary rock is overlain by 6m of microporphyritic basalt that forms a waterfall (Francis et al., 1970). The basalt is probably one of the highest lavas of the Spout of Ballochleam Lava Member.
Thickness: At least 45 m
Geographical Limits: The member is restricted to the valley of the Endrick Water around Cringate [NS 685 873], between the Fintry Hills and the south-western Gargunnock Hills, north-east of Glasgow.
Parent Unit: Clyde Plateau Volcanic Formation (CPV)
Previous Name(s): Cringate Interbasaltic Beds (-3959)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Section  Endrick Water, between the Fintry Hills and the south-western Gargunnock Hills, north-east of Glasgow Francis et al, 1970 
Reference Section  Left-bank tributary of the Endrick Water, near Cringate, south-western Gargunnock Hills, north-east of Glasgow Francis et al, 1970 
Reference(s):
Francis, E H, Forsyth, I H, Read, W A and Armstrong, M. 1970. The geology of the Stirling district. Memoir of the Geological Survey of Great Britain, Sheet 39 (Scotland). 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
S039