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. 
Strahan, A and others, 1914. The geology of the South Wales Coalfield, Part II. The country around Haverfordwest. Memoir of the Geological Survey of Great Britain. 
Dixon, E.E.L.. Geological Survey of Great Britain. 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. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E080 E089