| Computer Code: |
TNCR |
Preferred Map Code: |
TCr |
| Status Code: |
Full |
| Age range: |
Caradoc Series (O4)
— Caradoc Series (O4) |
| Lithological Description: |
Bedded coarse-grained dacitic tuff and lapilli-tuff, sparsely garnetiferous. |
| Definition of Lower Boundary: |
Taken at the base of pyroclastic sequence unconformably overlying bedded sandstone of the Seathwaite Fell Sandstone Formation or andesite of the Birker Fell Andesite Formation. |
| Definition of Upper Boundary: |
Conformable contact with welded lapilli-tuff of the Thirlmere Member, or with that of the Lincomb Tarns Formation (undivided). |
| Thickness: |
Up to about 8m, except on Great Howe and Castle Rock, Thirlmere, where up to 280m |
| Geographical Limits: |
North Lake District around Thirlmere Reservoir. |
| Parent Unit: |
Lincomb Tarns Tuff Formation (LTA)
|
| Previous Name(s): |
Tarn Crags Member [Obsolete Name and Code: Use TNCR]
(-4931)
|
| Alternative Name(s): |
none recorded or not applicable
|
| Stratotypes: |
| Reference Section |
Tarn Crags. |
| Reference Section |
Crags near Black Crag Gill (Steel Fell). |
| Reference(s): |
| Millward, D. 1998. Summary of the geology east of Thirlmere, part of 1:10000 Sheet NY31NW. British Geological Survey Technical REport WA/98/17. |
| Woodhall, D G, 1998. The geology of the Wythburn, Thirlmere and Fairfield areas of the north-east Lake District. British Geological Survey Technical Report WA/98/07. |
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: |
|
E029
|
