| Computer Code: |
SGT |
Preferred Map Code: |
SGT |
| Status Code: |
Pending Upgrade |
| Age range: |
Soudleyan Substage (OY)
— Soudleyan Substage (OY) |
| Lithological Description: |
Grey porcellanous felsic ash-flow tuffs and interbedded volcaniclastic sandstones, with local thin mudstones. |
| Definition of Lower Boundary: |
Conformably overlies mudstones and siltstones of the Pen-plaenau Siltstone Formation. |
| Definition of Upper Boundary: |
Conformably overlain by mudstones of the Allt-tair-ffynnon Formation or Teirw Siltstone Formation. |
| Thickness: |
30 to 90m |
| Geographical Limits: |
Not defined. |
| Parent Unit: |
Not Available (!)
|
| Previous Name(s): |
Swch Gorge Tuff [Obsolete Name and Code: Use SGT]
(-1816)
|
| Alternative Name(s): |
none recorded or not applicable
|
| Stratotypes: |
| none recorded or not applicable |
| Reference(s): |
| Brenchley, P J. 1978. The Caradocian rocks of the North and West Berwyn Hills. Geological Journal, Vol. 13, 137-164. |
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: |
|
E120
E136
E137
|
