The BGS Lexicon of Named Rock Units — Result Details

Mynydd-Tarw Tuff Member

Computer Code: MYTT Preferred Map Code: MtT
Status Code: Full
Age range: Caradoc Series (O4) — Caradoc Series (O4)
Lithological Description: Massive, pale grey, fine-grained tuff.
Definition of Lower Boundary: Underlain by mudstones of the Llangynog Formation.
Definition of Upper Boundary: Overlain by mudstones of the Llangynog Formation.
Thickness: c. 3.5m at Blaen-y-cwm, thins eastward (Wedd et al., 1929).
Geographical Limits: Central Berwyn Hills of Oswestry (137) and Bala (136).
Parent Unit: Llangynog Formation (LGF)
Previous Name(s): Mynydd-Tarw Ash (-1720)
Alternative Name(s): none recorded or not applicable
Type Area  Outcrops around Blaen-y-cwm. 
Wedd, C B, Smith, B, King, W B R and Wray, D A. 1929. Geology of the country around Oswestry. Memoir of the Geological Survey of Great Britain, Sheet 137. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E136 E137