Computer Code: |
YA |
Preferred Map Code: |
YA |
Status Code: |
Pending Upgrade |
Age range: |
Ashgill Series (OA)
— Ashgill Series (OA) |
Lithological Description: |
Very silty mudstones with abundant siltstone laminae and scattered thin beds of sandstone. Units of thick-bedded sandstone locally present. Slump folding and destratification commonly present. |
Definition of Lower Boundary: |
Sharp incoming of mudstones with siltstone laminae and no burrows, above burrow mottled mudstones of the Nantmel Formation. Locally rests sharply on top of Doldowlod Conglomerate Member of Nantmel Formation. |
Definition of Upper Boundary: |
Either gradational and taken at incoming of sandstone dominant sequence of Scrach Formation, or sharp, where overlain by mudstones lacking silt laminae of the Cwmere Formation or Tycwtta Mudstones. |
Thickness: |
Up to 1200 metres. |
Geographical Limits: |
Central Wales. |
Parent Unit: |
Not Applicable (-)
|
Previous Name(s): |
none recorded or not applicable
|
Alternative Name(s): |
none recorded or not applicable
|
Stratotypes: |
Type Section |
Road section on A470 at base of hill, known as Yr Allt, north of Newbridge on Wye. |
Reference(s): |
none recorded or not applicable |
1:50K maps on which the lithostratigraphical unit is found, and map code used: |
E179
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