Computer Code: |
ACV |
Preferred Map Code: |
notEntered |
Status Code: |
Full, pending ratification |
Age range: |
Neoproterozoic Era (AZ)
— Neoproterozoic Era (AZ) |
Lithological Description: |
Mainly quartz-rhyolites, possibly with tuffs, and some hornblende-andesite. |
Definition of Lower Boundary: |
Drawn at the base of the Clogwyn Group where the base of quartz-rhyolites possibly with tuffs and some hornblende-andesite; base not seen. |
Definition of Upper Boundary: |
Drawn at the conformable upward passage of the Clogwyn Group where rhyolites with some tuffs are conformably overlain by grits and feldspathic tuffs of the Tryfan Group. |
Thickness: |
305 metres approx. |
Geographical Limits: |
Clogwyn Melyn, near Nantlle, Caernarvonshire. |
Parent Unit: |
Not Entered (?)
|
Previous Name(s): |
none recorded or not applicable
|
Alternative Name(s): |
none recorded or not applicable
|
Stratotypes: |
Type Area |
Clogwyn Melyn, near Nantlle, Caernarvonshire. |
Reference(s): |
Morris, T O and Fearnsides, W G, 1926. The stratigraphy and structure of the Cambrian Slate Belt of Nantlle, (Caernarvonshire). Quarterly Journal of the Geological Society of London, Vol.82, p.250-303. |
1:50K maps on which the lithostratigraphical unit is found, and map code used: |
none recorded or not applicable |