| Computer Code: |
HMG |
Preferred Map Code: |
HM |
| Status Code: |
Full |
| Age range: |
Comley Series (EC)
— St David's Series (ED) |
| Lithological Description: |
Laterally-persistent coarse- to medium-grained green sandstones, interbedded with green and grey siltstones. |
| Definition of Lower Boundary: |
Base not exposed; possibly rests unconformably on Neoproterozoic rocks. |
| Definition of Upper Boundary: |
Conformably overlain by manganiferous siltstones of the Trwyn y Fulfran Formation. |
| Thickness: |
>190m |
| Geographical Limits: |
Pwllheli area, northwest Wales. |
| Parent Unit: |
Harlech Grits Group (HGG)
|
| Previous Name(s): |
Hell's Mouth Grits [Obsolete Name and Code: Use HMG]
(-3473)
|
| Alternative Name(s): |
Rhinog Formation
|
| Stratotypes: |
| Type Section |
Trwyn y Ffosle cliff section, from sea level to the base of the overlying Trwyn-y-Fulfran Formation. |
| Reference(s): |
| Young, T P, Martin, F, Dean, W T and Rushton, A W A. 1994. Cambrian stratigraphy of St Tudwal's Peninsula, Gwynedd, northwest Wales. Geological Magazine, Vol.131, 335-360. |
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: |
|
E134
|
