| Computer Code: |
SPN |
Preferred Map Code: |
notEntered |
| Status Code: |
Full |
| Age range: |
Hirnantian Age (OH)
— Rhuddanian Age (SR) |
| Lithological Description: |
Nodular limestone and pale grey mudstone. |
| Definition of Lower Boundary: |
Base of lowest nodular limestone or massive mudstone above the laminated mudstone of the Ashgill Formation. |
| Definition of Upper Boundary: |
Base of the black graptolitic mudstone of the main part of the Skelgill Formation. |
| Thickness: |
0.4-1.8m |
| Geographical Limits: |
Howgill Fells, the Lake District, Cross Fell and the Craven Inliers. |
| Parent Unit: |
Skelgill Formation (SKB)
|
| Previous Name(s): |
Basal Beds [Obsolete Name and Code: Use PLMA, BKBD, SPN]
(-3221)
|
| Alternative Name(s): |
none recorded or not applicable
|
| Stratotypes: |
| Type Section |
100m up Spen Gill from its confluence with Stockless Gill. |
| Reference(s): |
| Kneller, B C, Scott R W, Soper N J, Johnson E W and Allen P M, 1994. Lithostratigraphy of the Windermere Supergroup, Northern England. Geological Journal, Vol. 29, 219-240. |
| Rickards, R B, 1970. The Llandovery (Silurian) graptolites of the Howgill Fells (northern England). Monograph Palaeontological Society, London, 1-108. |
| Scott, R W and Kneller, B C, 1990. A report on the Ashgill and Llandovery age rocks of Sheet 38 (Ambleside). British Geological Survey Technical Report WA/90/63. |
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: |
| none recorded or not applicable |
