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
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 
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: