The BGS Lexicon of Named Rock Units — Result Details

Manchester Marls Formation

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 (-4196)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Reference Section  Mill Hill Borehole (SJ98NW/28) 91.44 to 119.79m (bottom of hole; Manchester Marls not bottomed). 
Reference Section  Tiviot Colour Works Borehole (SJ89SE/41). 109'0" to 319'0". Taylor and others, 1963, p154. 
Type Area  Manchester: formerly exposed crossing the Irk Valley. 
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