The BGS Lexicon of Named Rock Units — Result Details

Laig Gorge Limestone Member

Computer Code: LAGL Preferred Map Code: LagL
Status Code: Full
Age range: Turonian Age (KT) — Turonian Age (KT)
Lithological Description: Medium- to coarse-grained poorly sorted sandstones and conglomerates of the Laig Gorge Sandstone Member are overlain by sandy and micritic limestones of this member.
Definition of Lower Boundary: The lower boundary is at a burrowed contact with the Laig Gorge Sandstone Member on Eigg, but is considered absent in successions of the Inner Hebrides Group in Mull and Morvern by Mortimore, Wood and Gallois (2001). This member is equivalent to the Strathaird Limestone Formation of Braley (1990) and Lowden et al. (1992). See note in supplementary information.
Definition of Upper Boundary: At Strathaird on Skye the upper boundary of the member is disconformable at an erosion surface above which a coarse, poorly sorted, silicified chalk and flint conglomerate of the Clach Alasdair Conglomerate Member is found. At Laig Gorge on Eigg the boundary is a sharp contact with a basalt but the limestone appears unbaked.
Thickness: 3.0m at Laig Gorge, Eigg, and about 1.6m on Skye.
Geographical Limits: The Member is identified and named from Laig Gorge [NM 4735 8750] on the island of Eigg and on Skye (where it is called the Strathaird Limestone Formation but see note in supplementary information). Described as being found in Laig Gorge within the "smaller upper gorge between the waterfall caused by the quartz porphyry intrusion and the lowest basalt flow" (Emeleus, 1997).
Parent Unit: Strathaird Limestone Formation (STRL)
Previous Name(s): Laig Limestone Formation (-4142)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Reference Section  Strathaird on Skye. Where 1.56m of hard grey micritic limestone between the Laig Gorge Sandstone Member and the Clach Alasdair Conglomerate Member is visible in a stream section. 
Type Section  Laig Gorge on Eigg. Present in the 'upper gorge' where 0.85 of sandy limestone with an upper burrowed surface is overlain by 1.6m of hard micritic limestone. 
Reference(s):
Emeleus, C H. 1997. Geology of Rum and the adjacent islands. Memoir (sheet) of the Geological Survey of Great Britain (Scotland) (60). (The Stationery Office for the British Geological Survey.) 171pp. 
Lowden, B, Braley, S, Hurst, A and Lewis, J, 1992. Sedimentological studies of the Cretaceous Lochaline Sandstone, NW Scotland. 159-162 in Parnell, J (editor), Basins on the Atlantic Seaboard: Petroleum Geology, Sedimentology and Basin Evolution. Geological Society of London Special Publication, No.62. 
Mortimore, R N, Wood, C J and Gallois, R W, 2001. British Upper Cretaceous Stratigraphy. Geological Conservation Review Series. No. 23. (Peterborough: Joint Nature Conservation Committee.) 
Braley, S M. 1990. The Sedimentology, Palaeoecology and Stratigraphy of Cretaceous Rocks in N.W. Scotland. Unpublished PhD Thesis CNAA, Polytechnic SouthWest (now University), Plymouth. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
S060