The BGS Lexicon of Named Rock Units — Result Details

Garwallt Tuff Member

Computer Code: GWT Preferred Map Code: notEntered
Status Code: Pending Upgrade
Age range: Costonian Substage (OO) — Costonian Substage (OO)
Lithological Description: Lapilli-crystal tuff with varying amounts of epiclastic material.
Definition of Lower Boundary: Conformably overlies mudstones of the Llangynog Formation.
Definition of Upper Boundary: Conformably overlain by volcaniclastic mudstones of the Llangynog Formation.
Thickness: 5 to 6m
Geographical Limits: No data.
Parent Unit: Llangynog Formation (LGF)
Previous Name(s): Garwallt Ash (-3450)
Alternative Name(s): none recorded or not applicable
none recorded or not applicable
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: