| Computer Code: |
GCG |
Preferred Map Code: |
GCg |
| Status Code: |
Full |
| Age range: |
Caradoc Series (O4)
— Caradoc Series (O4) |
| Lithological Description: |
Aphyric, fine-grained andesite lava, flow banded at base and autobrecciated at top. |
| Definition of Lower Boundary: |
Flow banded andesite lava rests sharply on volcaniclastic rocks; in part rests unconformably on the Skiddaw Group (mudstones). |
| Definition of Upper Boundary: |
Brecciated andesite lava overlain sharply by volcaniclastic rocks. |
| Thickness: |
Up to 200m |
| Geographical Limits: |
North Lake District near Borrowdale. (Ashness Wood to Dale Head). |
| Parent Unit: |
Birker Fell Andesite Formation (BFA)
|
| Previous Name(s): |
none recorded or not applicable
|
| Alternative Name(s): |
none recorded or not applicable
|
| Stratotypes: |
| Reference Section |
Crags near and around village of Grange. |
| Reference(s): |
| Beddoe-Stephens, B. 1997. The initiation of Borrowdale Volcanism in the Ordovician Lake District as indicated by basal volcaniclastic deposits. British Geological Survey Technical Report WG/97/14. |
| Beddoe-Stephens, B. 1996. Mapping; petrology and geochemistry of the Borrowdale Volcanic Group on 1:10k sheets NY21NE and NY21NW. Part of the 1:50k Sheet 29 (Keswick). British Geological Survey Technical Report MPSR/96/16. |
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: |
|
E029
|
