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):
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. 
Definition not published. 
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. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E094