The BGS Lexicon of Named Rock Units — Result Details

Upper Marl Group

Computer Code: UMG Preferred Map Code: notEntered
Status Code: Full, pending ratification
Age range: Pragian Age (DP) — Pragian Age (DP)
Lithological Description: Red, locally nodular, mudstones, fine- to very fine-grained sandstones and intraformational conglomerates: lithology represents fining up sequences (cyclothems).
Definition of Lower Boundary: Drawn at the base of the Upper Marl Group where it rests conformably on the Sandstone and Marl Group.
Definition of Upper Boundary: Drawn at the conformable upward passage from the top of the upper marl group to the base of the green flaggy sandstones formation of the Casheston Group.
Thickness: 106 metres to 305 metres approx.
Geographical Limits: South Pembrokeshire (Dyfed), southwest Wales.
Parent Unit: Not Entered (?)
Previous Name(s): none recorded or not applicable
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Area  Pembrokeshire. Between Milford Haven and the Pembrokeshire Coalfield. 
Reference(s):
Allen, J R L, 1963. Depositional features of Dittonian Rocks. Pembrokeshire compared with the Welsh Borderland. Geological Magazine, Vol.100, 385-400. 
Dixon, E E L, 1921. The Geology of the South Wales Coalfield, Part XIII , the country around Pembroke and Tenby, being an account of the region comprised in sheets 244 and 245. Memoir of the Geological Survey of Great Britain (HMSO). 
Strahan A, Cantrill T C, Dixon E E L, Thomas H H and Jones O T. 1914. The geology of the South Wales Coalfield. Part XI. The country around Haverfordwest. Memoir of the Geological Survey of Great Britain. (London: HMSO). 262pp. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E080 E089