The BGS Lexicon of Named Rock Units — Result Details

Llanfwrog Formation

Computer Code: LLW Preferred Map Code: notEntered
Status Code: Full
Age range: Chadian Substage (CI) — Chadian Substage (CI)
Lithological Description: Red and green mudstone, marl, sandstone and cornstone with sporadic thin, impure limestone beds.
Definition of Lower Boundary: Unconformity on Silurian seen in stream section at Llanfwrog (SJ 1049 5782) and at Lady Bagots Drive (SJ 1022 5952).
Definition of Upper Boundary: Overlain by lagoonal-peritidal limestones at Lady Bagots Drive (SJ 1026 5975).
Thickness: 20-60m
Geographical Limits: North Denbighshire, Vale of Clwyd, Dyserth.
Parent Unit: Not Entered (?)
Previous Name(s): Basement Beds (-3812)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Reference Section  Stream section in Lady Bagots Drive, Rhewl, near Ruthin, Clwyd. 
Type Section  Stream section, 400m to 1020m west of Llanfwrog church, Ruthin, Clwyd. 
Reference Section  Section, Lady Bagots Drive, Rhewl, near Ruthin, Clwyd. 
Reference(s):
Williamson, I T and Addison, R. Not yet published. The geology of the area around Flint. In Preparation for the Memoir of the British Geological Survey, Sheet 108 (England and Wales). 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
none recorded or not applicable