The BGS Lexicon of Named Rock Units — Result Details

Hallaig Sandstone Member

Computer Code: HLGS Preferred Map Code: notEntered
Status Code: Pending Upgrade
Age range: Sinemurian Age (JS) — Sinemurian Age (JS)
Lithological Description: The Hallaig Sandstone Member is composed of moderately well-cemented medium to fine sand. Three cycles of grading were interpreted; from bioturbated sandstones with thin siltstones at the base to cross-stratified sandstones at the top of the unit. Hasselbo et al (1988, 1999) and Hesselbo and Coe (2000) include this Member within their redefined Pabay Shale Formation, which has not been accepted by the British Geological Survey. It was originally the highest sandstone within the Broadford Beds and hence is now the highest Member within the Ardnish Formation, as defined by Morton (1999).
Definition of Lower Boundary: Unseen.
Definition of Upper Boundary: Unconformably overlain (locally) by Pabay Shale Formation - see Morton, 1999, and reply by Hesselbo et al.
Thickness: ?50m+
Geographical Limits: Skye/Sea of the Hebrides Basin.
Parent Unit: Ardnish Formation (ADS)
Previous Name(s): Hallaig Sandstone (-632)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Partial Type Section  Cliff section near Boreaig, southern Skye. Hesselbo et al, 1998. 
Reference(s):
Cox, B M, Page, K N and Morton, N, 2002. The Middle Jurassic stratigraphy of Scotland. In Cox, B M and Sumbler, M G (editors), British Middle Jurassic Stratigraphy. Geological Conservation Review Series, Vol.26. (Peterborough: Joint Nature Conservation Committee/Chapman and Hall.) 
Morton, N. 1999. Discussion of the Lower Lias Group of the Hebrides Basin; reply by Hesselbo, S P, Oates, M J and Jenkyns, H C. Scottish Journal of Geology, Vol.35 Part 1, 85-88. 
Hesselbo, S P, Oates, M J and Jenkyns, H C. 19998. The Lower Lias Group of the Bebrides Basin. Scottish Journal of Geology, Vol.34, Part 1, 23-60. 
Hesselbo, S P and Coe, A L. 2000. Jurassic sequences of the Hebrides Basin, Isle of Skye, Scotland. In: Graham, J R and Ryan, A, (editors). Field trip guidebook, International Association of Sediementologists Meeting, Dublin, 2000, (University of Dublin, Ireland), p41-58. 
Morton, N and Hudson, J D, 1995. Field Guide to the Jurassic of the Isles of Raasay and Skye, Inner Hebrides, north-west Scotland. In: Taylor, P D (editor), Field Geology of the British Jurassic. Geological Society of London, 209-280. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
none recorded or not applicable