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): Greensand Of Morvern [Obsolete Name And Code: Use MOGR] (GSM)
Cenomanian Greensand (-1706)
Alternative Name(s): none recorded or not applicable
Stratotypes:
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]. 
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.) 
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. 
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). 
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. 
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. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
S043 S043 S044 S044 S052 S070 S081