| Computer Code: |
MCW |
Preferred Map Code: |
MCw |
| Status Code: |
Index Level |
| Age range: |
Homerian Age (SH)
— Gorstian Age (SG) |
| Lithological Description: |
[Obsolete: use CDW] Consists of variable proportions of fine-grained, blue-grey, calcareous siltstones with interbedded laminated siltstone and silty mudstone. The calcareous divisions form pronounced ridges with marked cleavage. |
| Definition of Lower Boundary: |
Taken at base of calcareous siltstones overlying coarse siltstones or fine-grained sandstones of the Lower Coldwell Beds. |
| Definition of Upper Boundary: |
Transitional, taken at incoming of non calcareous laminated siltstones of the Upper Coldwell Beds. |
| Thickness: |
c. 30 metres, at type section, lateral variation (+-) 10 metres. |
| 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 |
Coldwell, near Hawkshead, Cumbria, Sheet 38 (Ambleside). |
| Reference(s): |
| Marr, J E. 1878. On some well defined Life Zones in the lower part of the Silurian (Sedgwick) of the Lake District. Quarterly Journal of the Geological Society, Vol.34, p.871-885. |
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: |
|
E039
|
