Computer Code: |
MODS |
Preferred Map Code: |
MoDS |
Status Code: |
Full |
Age range: |
Triassic Period (T)
— Triassic Period (T) |
Lithological Description: |
The Monadh Dubh sandstone Formation consists of 4 members, but was shown as one unit on the 50k maps. From the base these members are Shellesder, A'Mharagach, Sgaorishal and Allt Dubh.
The base of the unit lies directly on the Torridonian and comprises coarse, continental-derived conglomerates. Gradually the succession fines upwards and the top 25 m (two members) are dominated by fine sand and lacustrine carbonate rocks with ostracods. |
Definition of Lower Boundary: |
Direct, unconformable contact on Torridonian sandstones. |
Definition of Upper Boundary: |
Jurassic transgression - change from continental derived sediments - not seen? |
Thickness: |
82 m+ |
Geographical Limits: |
Isle of Rum |
Parent Unit: |
New Red Sandstone Supergroup (NRS)
|
Previous Name(s): |
none recorded or not applicable
|
Alternative Name(s): |
none recorded or not applicable
|
Stratotypes: |
Reference Section |
Monadh Dubh, northwest Rum. Emeleus, 1997. |
Reference(s): |
Steel, R J. 1974. New Red Sandstone piedmont and floodplain sedimentation in the Hebridean province, Scotland. Journal of Sedimentary Petrology, Vol.44, 336-357. |
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: |
S060
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