Computer Code: |
HAF |
Preferred Map Code: |
notEntered |
Status Code: |
Index Level |
Age range: |
Namurian Stage (CN)
— Namurian Stage (CN) |
Lithological Description: |
[Obsolete: use BSG, CFS, GS, PECH] Comprises Cefn-y-Fedw Sandstone at base (quartzose sandstone), replaced laterally by chert and mudstone in the type area; overlain by the Holywell Shales (grey and black mudstone with subsidiary sandstones) and Gwespyr Sandstone (feldspathic sandstone). |
Definition of Lower Boundary: |
Base of Cefn-y-Fedw Sandstone (member) where present; overlies Minera Formation (limestone with interbedded sandstones). In type area, at base of Pentre Chert (member), unconformably overlies Cefn Mawr Limestone Formation. |
Definition of Upper Boundary: |
Top of Gwespyr Sandstone (member). |
Thickness: |
250 - 350 metres. |
Geographical Limits: |
Flintshire Coalfield, North Wales. |
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 |
Bryn Mawr Quarry, Pentre Halkyn, Clwyd. |
Reference(s): |
Campbell, S D G, and Hains, B A. 1988. Deeside (North Wales) thematic geological mapping. British Geological Survey Technical Report, WA/88/2. p.78-79. |
1:50K maps on which the lithostratigraphical unit is found, and map code used: |
E108
|