| Computer Code: |
MM |
Preferred Map Code: |
MM |
| Status Code: |
Full |
| Age range: |
Guadalupian Epoch (PUG)
— Lopingian Epoch (PUL) |
| Lithological Description: |
Red marl (calcareous mudstone and siltstone) with thin beds of fossiliferous marine limestone and dolomite; locally green; sandy in places especially in top part; local breccias and pebbly beds. (Tonks and others, 1931, p.165; Taylor and others, 1963, p.53). |
| Definition of Lower Boundary: |
Conformable upward change from red sandstones (Collyhurst Sandstone) into red marls; a pebbly bed was included in the base of the Manchester Marls at Stockport by Taylor and others, 1963, p.53. |
| Definition of Upper Boundary: |
Conformable upward passage into red sandstones of the Sherwood Sandstone Group. |
| Thickness: |
45 - 60m in Manchester; more in Stockport; dies out west of St. Helens. |
| Geographical Limits: |
Lancashire, Cheshire. |
| Parent Unit: |
Cumbrian Coast Group (CCO)
|
| Previous Name(s): |
Manchester Marl [Obsolete Name and Code: Use MM]
(-4196)
|
| Alternative Name(s): |
none recorded or not applicable
|
| Stratotypes: |
| Type Area |
Manchester: formerly exposed crossing the Irk Valley. |
| Reference Section |
Mill Hill Borehole (SJ98NW/28) 91.44 to 119.79 m (bottom of hole; Manchester Marls not bottomed). |
| Reference Section |
Tiviot Colour Works Borehole (SJ89SE/41). 109' 0" to 319' 0" (Taylor and others, 1963, p.154). |
| Reference(s): |
| Tonks, L H, Jones, R C B, Lloyd, W and Sherlock, R L, 1931. The geology of Manchester and the south-east Lancashire Coalfield. Memoir of the Geological Survey of England and Wales. |
| Taylor, B J, Price, R H and Trotter, F M. 1963. Geology of the country around Stockport and Knutsford. Memoir of the Geological Survey of Great Britain. |
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: |
|
E075
E097
E085
E098
E084
E067
|
