| Computer Code: |
BTD |
Preferred Map Code: |
notEntered |
| Status Code: |
Full |
| Age range: |
Langsettian Substage (CA)
— Bolsovian Substage (CC) |
| Lithological Description: |
[Obsolete: use PCM]
Grey and dark grey mudstones with subsidiary feldspathic sandstones, siltstones, seatearths (fireclays) and coal seams. |
| Definition of Lower Boundary: |
At junction (conformable) with underlying Gwespyr Sandstone (Halkyn Formation). |
| Definition of Upper Boundary: |
At junction (conformable, diachronous) with overlying Buckley Formation. |
| Thickness: |
Up to c.400 metres. |
| Geographical Limits: |
Flintshire Coalfield, North Wales. Possible extension to all the North Wales Coalfields. |
| 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 Section |
Bettisfield Colliery No.2 Shaft. |
| Reference(s): |
| none recorded or not applicable |
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: |
|
E108
|
