The BGS Lexicon of Named Rock Units — Result Details

Lower Mottled Mudstone Member

Computer Code: LMM Preferred Map Code: LMM
Status Code: Pending Upgrade
Age range: Wenlock Epoch (SW) — Wenlock Epoch (SW)
Lithological Description: Calcareous siltstone, dark grey to black mudstone and irregular mottled mudstone. Shelly fauna. Massive bedding.
Definition of Lower Boundary: Contrasts with the ribbon-banded silty mudstones of the Nantglyn Flags.
Definition of Upper Boundary: Contrasts with the ribbon-banded silty mudstones of the Nantglyn Flags.
Thickness: 12 - 76m
Geographical Limits: Not defined.
Parent Unit: Nantglyn Flags Formation (NGF)
Previous Name(s): Mottled Mudstones (-2294)
Alternative Name(s): none recorded or not applicable
Stratotypes:
none recorded or not applicable
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. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E120 E149 E094 E107