The BGS Lexicon of Named Rock Units — Result Details

Builth Mudstones Formation

Computer Code: BMD Preferred Map Code: BMd
Status Code: Pending Upgrade
Age range: Wenlock Epoch (SW) — Wenlock Epoch (SW)
Lithological Description: Laminated silty mudstones.
Definition of Lower Boundary: In-coming of pervasively laminated silty mudstones gradationally overlying the Dolfawr Mudstones, or sharply overlying the Alpine Bridge Member of the Cerig Formation.
Definition of Upper Boundary: Not yet diagnosed.
Thickness: Not yet assessed.
Geographical Limits: Central Wales and Welsh Borders.
Parent Unit: Not Applicable (-)
Previous Name(s): none recorded or not applicable
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Section  River Wye north west of Builth Wells, from 300 metres below railway bridge up river for 3km. 
Reference(s):
none recorded or not applicable
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E196 E179