Computer Code: |
UNF |
Preferred Map Code: |
notEntered |
Status Code: |
Index Level |
Age range: |
Ludlow Epoch (SU)
— Ludlow Epoch (SU) |
Lithological Description: |
[Obsolete: use NGF] Comprises ribbon-banded mudstones, blue grey, thin-bedded to shaly. More generally flaggy and in places massive. More weathered than overlying group. |
Definition of Lower Boundary: |
Drawn at the base of the Neodiversograptus Nilssoni zone where ribbon-banded mudstone conformably rests upon part ribbon banded mudstone with more frequent silt of the Bryn Sylldy Formation. |
Definition of Upper Boundary: |
Drawn at the conformable upward passage of sandstones, silty mudstones and disturbed beds of the Upper Nantglyn Flags, with a facies change to striped, silty mudstones and subordinate sandstones. |
Thickness: |
From 75 metres to approx. 600 metres. |
Geographical Limits: |
Nantglyn, Denbighshire. |
Parent Unit: |
none recorded or not applicable
|
Previous Name(s): |
none recorded or not applicable
|
Alternative Name(s): |
Nantglyn Flags Formation
|
Stratotypes: |
Type Area |
From Tywyn through Eglwysbach to Llanrwst, through Oerfa across the Denbigh Moors as far as Llech Daniel. |
Type Area |
Through Clocaenog Forest, terminating against the Gwaynynog Fault. Sheet (120) Corwen. |
Type Area |
From Llansannan through Moel Grugoer to Bylchau. |
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. |
Boswell, P G H, 1926. A contribution to the geology of the eastern part of the Denbighshire Moors. Quarterly Journal of the Geological Society, Vol.82, p.562. |
1:50K maps on which the lithostratigraphical unit is found, and map code used: |
E107
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