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
|