| Computer Code: |
GO |
Preferred Map Code: |
GoM |
| Status Code: |
Full |
| Age range: |
Pliensbachian Age (JE)
— Pliensbachian Age (JE) |
| Lithological Description: |
[Obsolete: use DYS] Interbedded silty, micaceous grey mudstones and fine-grained flaggy sandstones and noduler ironstones; sandstone defines base locally. |
| Definition of Lower Boundary: |
Generally gradational boundary with non-silty mudstones of remainder of Brant Mudstone Formation. Locally, base is defined by a sandstone that forms a slight topographical feature. |
| Definition of Upper Boundary: |
Sharp contact with basal sandstones of Marlstone Rock Formation. |
| Thickness: |
c. 15 to 25m |
| Geographical Limits: |
Mid Lias age silts and silty clays are mapped in southern part of 1:50k sheet 127 (Grantham) southwards and southwestwards through parts of Lincolnshire, Leicestershire (including former Rutland) and Northamptonshire. May be equivalent of Dyrham Siltstone Formation. |
| Parent Unit: |
none recorded or not applicable
|
| Previous Name(s): |
Middle Lias Mudstone and Siltstones [Obsolete Name and Code: Use GO]
(-4681)
|
| Alternative Name(s): |
none recorded or not applicable
|
| Stratotypes: |
| Type Area |
Around Great Gonerby, Grantham |
| Reference(s): |
| Berridge, N G, Pattison, J, Samuel, M D A, Brandon, A, Howard, A S, Pharaoh, T C, and Riley, N J. 1999. Geology of the Grantham district. Memoir of the British Geological Survey, sheet 127 (England and Wales). |
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: |
|
E127
|
