The BGS Lexicon of Named Rock Units — Result Details

Craigmaddie Muir Sandstone Member

Computer Code: CRMS Preferred Map Code: notEntered
Status Code: Full
Age range: Asbian Substage (CR) — Brigantian Substage (CX)
Lithological Description: Sandstone, white, cross bedded, with pebbly bands (beds) in places. Locally, interbedded with mudstone and rare intercalations of volcanic detritus. Strata within the member were described by Tait (1973) as fine-grained, buffweathering quartz arenite with conglomerate lenses that consist mainly of mudstone intraclasts. Tait (1973) interpreted the sandstone member as the deposits of a meandering river system. Visean (?Asbian-Brigantian).
Definition of Lower Boundary: The lower boundary of the Craigmaddie Muir Sandstone Member is mapped on Craigmaddie Muir [NS 5820 7652] and Muirhouse Muir [NS 5723 7785] and placed where sandstones without interbeds of conglomerate are observed at outcrop (BGS, 1987b; see also BGS, 1987c). The underlying Douglas Muir Quartz-Conglomerate Member is typically conglomerate with sandstone interbeds and, toward the top of the member, sandstone with pebbles or conglomerate beds. The lower boundary of the Craigmaddie Muir Sandstone Member had previously been mapped slightly lower in the sequence by Tait (1973) who noted it to be gradational containing 'lenses of conglomerate of similar composition' to the underlying Douglas Muir Quartz-Conglomerate Member near the base.
Definition of Upper Boundary: The upper boundary of the Craigmaddie Muir Sandstone is placed at the base of the Balmore Marine Band (Hall et al., 1998, fig. 9). This is at a higher position than that of Clough et al. (1925, fig. 2) who placed it at the top of the main sequence of sandstones about 45 m below the Craigenglen Beds, but at a lower position than Tait (1973) who placed the boundary beneath the Balgrochan Beds. Tait's (1973) informal division 'lower Craigmaddie Muir Sandstone Member' equates with the Craigmaddie Muir Sandstone Member as presented here.
Thickness: Between 170 and 180 m.
Geographical Limits: The member is confined to the fault-bounded block south of the Craigend and Campsie faults and north of the Bankend and Glorat faults, extending from Muirhouse Muir [NS 576 777] eastwards to Craigmaddie Muir [NS 590 765], Craigend Muir [NS 585 776], and the vicinity of Lennoxtown [NS 626 780], north-east of Milngavie, Strathclyde.
Parent Unit: Lawmuir Formation (LWM)
Previous Name(s): Craigmaddie Sandstones [Obsolete Name and Code: Use CRMS] (-1459)
Craigmaddie Muir Sandstones [Obsolete Name and Code: Use CRMS] (-4569)
Craigmaddie Sandstone Formation [Obsolete Name and Code: Use CRMS] (-3957)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Partial Type Section  Partial type sections were described by Hall et al. (1998), who referred to the prominent outcrops of bedrock on Craigmaddie Muir exposing strata from the base and the middle parts of the member [NS 580 766 to 588 764]. 
Type Section  The type section of the upper part of the member (about 68 m thick), to its upper boundary placed at the base of the Balmore Marine Band, is recorded from exposures in the subsurface beneath Craigmaddie Muir in the Strathblane-Balmore tunnel (BGS Registration Number NS57NE/30) [NS 5895 7521]. 
Reference(s):
Dean, M T, Browne, M A E, Waters, C N and Powell, J H. 2011. A lithostratigraphical framework for the Carboniferous successions of northern Great Britain (onshore). British Geological Survey Research Report, RR/10/007. 165pp. 
Clough, C T, Hinxman, L W, Wilson, J S G, Crampton, C B, Wright, W B, Bailey, E B, Anderson, E M, and Carruthers, R G. 1925. The geology of the Glasgow district. Memoir of the Geological Survey of Great Britain, Sheets part 30, 31, 22 and 23 (Scotland). 
Hall, I H S, Browne, M A E and Forsyth, I H. 1998. Geology of the Glasgow district. Memoir of the British Geological Survey, Sheet 30E (Scotland). 
Tait, A M. 1973. Sedimentation of the Craigmaddie Muir Sandstone Formation, western Midland Valley of Scotland. Unpublished PhD thesis, University of Glasgow. 
British Geological Survey. 1987b. NS57NE. Solid Geology. 1:10 000. (Edinburgh: British Geological Survey.) 
British Geological Survey. 1987c. NS67NW. Solid Geology. 1:10 560. (Edinburgh: British Geological Survey.) 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
S030