The BGS Lexicon of Named Rock Units — Result Details

Morvern Greensand Formation

Computer Code: MOGR Preferred Map Code: MoGr
Status Code: Full
Age range: Cenomanian Age (KE) — Cenomanian Age (KE)
Lithological Description: Glauconitic calcareous sandstone, white to pale greenish. Some gritty beds and calcareous inclusions up to cobble size. Conspicuously shelly (mainly oysters) in parts.
Definition of Lower Boundary: The lower boundary is unconformable on various Jurassic and Triassic strata.
Definition of Upper Boundary: The upper boundary is at a [?]conformable contact with the overlying Lochaline White Sandstone Formation. However Braley (1990) and Lowden et al. (1992) regarded the Lochaline White Sandstone Formation as a member within this formation and considered the upper boundary as unconformable with the Gribun Chalk Formation.
Thickness: 0.3 to 13.4m, according to Rawson et al. (1978).
Geographical Limits: Known from the Morvern district and the Isle of Mull.
Parent Unit: Inner Hebrides Group (IHEB)
Previous Name(s): Cenomanian Greensand (-1706)
Greensand Of Morvern [Obsolete Name And Code: Use MOGR] (GSM)
Alternative Name(s): none recorded or not applicable
Type Section  Beinn Iadain In Braley (1990) two sections given on Beinn Iadain as [NM 6917 5490 and NM 6965 5645] the former presumed to be the section described in Judd (1878) and Lee and Bailey (1925). Mortimore et al. (2001) give their locality as Beinn Iadain, Morvern [NM 670 541 to NM 689 528] and also a site called Beinn na H-Uamha at [NM 68]. 
Reference Section  Alt na Teangaigh, Isle of Mull. Stream section showing attenuated succession. Mortimore et al., 2001. 
Reference Section  Auchnacraig Cliff (Braley, 1990) Two section showing slightly different lithstratigraphical relationship [see Mortimore et al., 2001]. 
Lee, G W and Bailey, E B. 1925. The pre-Tertiary Geology of Mull, Loch Aline and Oban. Memoir of the Geological Survey of Great Britain, parts of Sheets 35, 43, 44, 45 and 52 (Scotland). 
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. 
Lee, G W and Pringle, J. 1932. A synopsis of the Mesozoic rocks of Scotland. Transactions of the Geological Society of Glasgow, Vol.19, 158-224. 
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. 
Rawson, P F, Curry, D, Dilley, F C, Hancock, J M, Kennedy, W J, Neale, J W, Wood, C J and Worrsam, B C. 1978. A correlation of Cretaceous rocks in the British Isles. Geological Society of London, Special Report No.9. 
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. 
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.) 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
S043 S043 S044 S044 S052 S070 S081