The BGS Lexicon of Named Rock Units — Result Details

Dyserth Limestone Group [Obsolete Name And Code: Use CLWYD]

Computer Code: DYL Preferred Map Code: notEntered
Status Code: Index Level
Age range: Holkerian Substage (CQ) — Asbian Substage (CR)
Lithological Description: Predominantly limestones with bands of carbonaceous mudstone. Lowest beds contain cherts and dolomites and dolomitic limestone.
Definition of Lower Boundary: Drawn at the base of the Dyserth Group where cyclic brown limestone conformably rests upon arenaceous limestone of the Basement Beds.
Definition of Upper Boundary: Drawn at the conformable upward passage of brown grey and white limestones of the Dyserth Group unconformably overlain by darker fine-grained limestones of the Teila Formation.
Thickness: 500 metres approx.
Geographical Limits: Confined to the north Wales coastal area of Great Orme, Little Orme, Llanddulas and Prestatyn.
Parent Unit: Not Entered (?)
Previous Name(s): none recorded or not applicable
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Area  Great Orme. 
Reference(s):
Neaverson, E. 1930. The Carboniferous rocks around Prestatyn, Dyserth, and Newmarket (Flintshire). Proceedings of the Geological Society of Liverpool, Vol.15, 179-212. 
George, T N, Johnson, G A L, Mitchell, M, Prentice, J E, Ramsbottam, W H C, Sevastopulo, G D and Wilson, R B. 1976. A correlation of the Dinantian rocks of the British Isles. Special Report of the Geological Society of London, No 7. 
Definition not published. 
Warren, P T, Price, D, Nutt, M J C and Smith, E G. 1984. Geology of the country around Rhyl and Denbigh. Memoir for 1:50 000 geological sheets 95 and 107 and parts of sheets 94 and 106. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E094