The BGS Lexicon of Named Rock Units — Result Details

Llanfawr Mudstone Formation

Computer Code: LRM Preferred Map Code: LrM
Status Code: Full
Age range: Abereiddian Stage (O2) — Caradoc Series (O4)
Lithological Description: Grey mudstone (few interbedded tuffs).
Definition of Lower Boundary: Faulted.
Definition of Upper Boundary: Not seen.
Thickness: Approximately 1000 metres.
Geographical Limits: North limit: near Cellws Farm (SO 0745 6345). West limit: Llanfawr Quarries. South limit: near Llandrindod Hall (SO 0642 6110), and East limit: near New Barn (SO 0958 6213).
Parent Unit: Not Applicable (-)
Previous Name(s): Nemagraptus Gracilis Shales (-1047)
Glyntograptus Teretiusalus Shales (-376)
Alternative Name(s): none recorded or not applicable
Type Section  Llanfawr Quarries which lie 700 metre north-east of the railway station, Llandrindod Wells. 
Reference Section  Unnamed dingle, 1.35 km east-south-east of railway station, Llandrindod Wells. 
Elles, G L. 1939. The stratigraphy and faunal succession in Ordovician rocks of Builth-Llandrindod inlier. Quarterly Journal of the Geological Society, Vol.95, p.383-445. 
1:50K maps on which the lithostratigraphical unit is found, and map code used: