| Computer Code: |
WDWR |
Preferred Map Code: |
notEntered |
| Status Code: |
Full |
| Age range: |
Oxfordian Age (JO)
— Oxfordian Age (JO) |
| Lithological Description: |
The formation comprises pale to dark grey and calcareous mudstone with occasional thin interbedded sandstone and siltstone. |
| Definition of Lower Boundary: |
The lower boundary is defined by a downward change pale, silty mudstone to hard oolitic limestone (Corallian Formation, Offshore) or sandstone (Seeley Formation). There is a corresponding decrease in gamma values and an increase in velocity. |
| Definition of Upper Boundary: |
The upper boundary is marked by a downward change from dark, hard mudstone (Kimmeridge Clay Formation (Offshore)) to paler, more calcareous mudstone. On geophysical logs, the boundary is usually characterised by a down-section decrease in gamma values and an increase in velocity. |
| Thickness: |
Very variable in thickness up to a maximum of c. 90 m on the East Midlands Shelf (e.g. Well 47/14a-2). |
| Geographical Limits: |
North Sea UK Quadrants 42, 43, 47, 48, 51 and 52. |
| Parent Unit: |
Humber Group (HMBG)
|
| Previous Name(s): |
none recorded or not applicable
|
| Alternative Name(s): |
none recorded or not applicable
|
| Stratotypes: |
| Type Section |
North Sea well 47/14a- 2; 878-966 m depth (Rhys, 1974, p.7; Lott and Knox, 1994. |
| Reference Section |
North Sea well 42/28- 1 at 674-728 m depth (Lott and Knox, 1994). |
| Reference Section |
North Sea well 47/09b- 5A at 885.5-907.5 m depth (Lott and Knox, 1994). |
| Reference Section |
North Sea well 47/18- 1 at 739-820.5 m depth (Lott and Knox, 1994). |
| Reference(s): |
| Lott, G K and Knox, R W O'B. 1994. 7. Post-Triassic of the Southern North Sea. In: Knox, R W O'B and Cordey, W G (eds.) Lithostratigraphic nomenclature of the UK North Sea. British Geological Survey, Nottingham. |
| Waters, C N, Smith, K, Hopson, P M, Wilson, D, Bridge, D M, Carney, J N, Cooper, A H, Crofts, R G, Ellison, R A, Mathers, S J, Moorlock, B S P, Scrivener, R C, McMillan, A A, Ambrose, K, Barclay, W J, and Barron, A J M. 2007. Stratigraphical Chart of the United Kingdom: Southern Britain. British Geological Survey, 1 poster. |
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: |
| none recorded or not applicable |
