The BGS Lexicon of Named Rock Units — Result Details

Ruallan Till Member

Computer Code: RNTI Preferred Map Code: RLN
Status Code: Full
Age range: Devensian Stage (QD) — Devensian Stage (QD)
Lithological Description: Stony sandy clay diamicton, matrix-supported, dark yellowish brown, fissile, massive, extremely compact, containing angular to sub-rounded clasts of gneissose psammite and semipelite, pink and grey granite and some Devonian sandstone and siltstone. Typical lodgement till with well developed north-easterly fabric and containing concavo-convex discontinuities that are commonly sand-filled.
Definition of Lower Boundary: Generally a gradational contact over 10 to 20cm, but locally a sharp, planar contact and change in colour from dark yellowish brown to "strong brown" (Munsell Soil), with underlying stony sandy clay diamictons of the Cantray Till Member.
Definition of Upper Boundary: Erosional contact with gravel of the Carn Monadh Gravel Formation at the Allt Odhar Interstadial site, otherwise overlain by various younger deposits or boundary at the ground surface.
Thickness: 3.5m
Geographical Limits: Sheet 84W (Fortrose), southeast of Inverness.
Parent Unit: Beinn an Uain Till Formation (BUTI)
Previous Name(s): Upper Member Of The Dalcharn Upper Till (-4302)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Section  Exposed towards the tops of river cliff sections of the Allt Dearg, 6km southwest of Cawdor, Nairnshire, in the vicinity of the Dalcharn Interglacial site. Walker, M J C and 6 others. 1992 
Reference(s):
Sutherland D G and Gordon, J E. (editors). 1993. The Quaternary of Scotland. Geological Conservation Review Series: 6. London: Chapman and Hall. 
Fletcher, T P et al. 1996. Geology of the Fortrose and eastern Inverness district. Memoir of the British Geological Survey, Sheet 84W (Scotland). 
Walker, M J and 6 others. 1992. Allt Odhar and Dalcharn: two pre-Late Devensian (Late Weichselian) sites in northern Scotland. Journal of the Quaternary Science, Vol.7, 69-86. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
S084