The BGS Lexicon of Named Rock Units — Result Details

Inner Hebrides Group

Computer Code: IHEB Preferred Map Code: notEntered
Status Code: Full
Age range: Cenomanian Age (KE) — Campanian Age (KC)
Lithological Description: Glauconitic sandstones, pure silica sands, silicified chalks, flints and conglomerates.
Definition of Lower Boundary: The lower boundary is unconformable on a varied "basement" at the erosion surface below the Morvern Greensand Formation.
Definition of Upper Boundary: The upper boundary is unconformable beneath the Paleocene lavas or conformable (?) beneath the Beinn Iadain Mudstone Formation of presumed Paleocene age.
Thickness: The group comprises a highly condensed sequence and is variable in thickness depending on the relative development of its constituent parts. The group may be as little as a few metres thick but is 10 to 15m on Mull and 11 to 22m in Morvern.
Geographical Limits: Known from the Inner Hebrides islands of Mull, Eigg, Skye, Scalpay, Soay and Raasay, and also from the Morvern district of the Scottish mainland.
Parent Unit: Not Applicable (-)
Previous Name(s): Chalk Of Mull - Morvern [Obsolete Name And Code: See IHEB And GRIB] (CHM)
Cretaceous Rocks (-2863)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Area  At various localities for the constituent formations in the Inner Hebrides and Morvern. Principal exposures are at Beinn Iadain and Loch Aline Mine in Morvern, at Gribun, Carsaig and Auchnacraig on Mull, at Clach Alasdair and Laig Gorge on Eigg and at Strathaird on Skye. 
Reference(s):
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.) 
Judd, J W. 1878. The secondary rocks of Scotland. Third paper. The strata of the Western Coast and Islands. With a note on the foraminifera and other organisms in the Chalk of the Hebrides by T R Jones. Quarterly Journal of the Geological Society of London, Vol.34, 600-743. 
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 Unpublished PhD Thesis CNAA, Polytechnic SouthWest (now University), Plymouth. 
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. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
none recorded or not applicable