The BGS Lexicon of Named Rock Units — Result Details

Pabay Shale Formation

Computer Code: PABS Preferred Map Code: PabS
Status Code: Pending Upgrade
Age range: Sinemurian Age (JS) — Pliensbachian Age (JE)
Lithological Description: Basal beds consist of fine-grained, dark, micaceous fissile mudstones. The remainder of the Formation consists of silty and micaceous mudstones. The unit is rich in infaunal and epifaunal benthic faunas, ammonites and belemnites. The unit coarsens upwards to the Scalpay Sandstone Formation, with thin, local, clastic coarsening cycles.
Definition of Lower Boundary: Abrupt facies change from Ardnish Formation sandstones to dark mudstones.
Definition of Upper Boundary: Diachronous and transitional to the Scalpay Sandstone Formation.
Thickness: 200m maximum
Geographical Limits: Sea of Hebrides Basin (mainly Skye and Raasay).
Parent Unit: Lias Group (LI)
Previous Name(s): Pabba Shale (-3601)
Pabba Beds [Obsolete Name And Code: See PABS] (PABB)
Pabba Shale Formation (-1111)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Reference Section  Hallaig, Isle of Raasay. Morton and Hudson, 1995. 
Type Section  Pabay Isle, north of Broadford Bay, Isle of Skye. Morton and Hudson, 1995. 
Reference Section  North shore of Loch Eishort, Skye. Morton and Hudson, 1995. 
Reference(s):
Morton, N. 1999b. Middle Hettangian (Lower Jurassic) ammonites from the Isle of Raasay, Inner Hebrides, and correlation of the Hettangian - lowermost Sinemurian Breakish Formation in the Skye area, north-western Scotland. Scottish Journal of Geology, Vol.35, Part 2, 119-130. 
Morton, N. 1965. The Bearrenaig Sandstone Series (Middle Jurassic) of Skye and Raasay. Scottish Journal of Geology, Vol.1, 189-216. 
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. 
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. 
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.) 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
S071 S081 S051