| Computer Code: |
CRI |
Preferred Map Code: |
CRI |
| Status Code: |
Index Level |
| Age range: |
Arenig Series (OR)
— Arenig Series (OR) |
| Lithological Description: |
[Obsolete: use ALL] Has the impersistent Garth Grit Member at its base, and comprises streaky mudstones and siltstones. Also includes fossiliferous Henllan Ash Member. |
| Definition of Lower Boundary: |
Base of Garth Grit - where present and by incoming of streaky mudstones above Afon Gam Formation. |
| Definition of Upper Boundary: |
Top of formation is the base of the mudstones overlying the Henllan Ash. |
| Thickness: |
0 to 340m |
| Geographical Limits: |
Not defined. |
| Parent Unit: |
none recorded or not applicable
|
| Previous Name(s): |
none recorded or not applicable
|
| Alternative Name(s): |
none recorded or not applicable
|
| Stratotypes: |
| Type Area |
Snowdon, Sheet 119. |
| Reference(s): |
| Lynas, B D T, 1973. The Cambrian and Ordovician rocks of the Migneint area, North Wales. Journal of the Geological Society, London, Vol.129, 481-503. |
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: |
|
E120
|
