| Computer Code: |
DO |
Preferred Map Code: |
DO |
| Status Code: |
Pending Upgrade |
| Age range: |
Ashgill Series (OA)
— Ashgill Series (OA) |
| Lithological Description: |
Micaceous siltstones and mudstones with subsidiary sandstone and limestone bands. Variable basal limestone (Dolhir Limestone Member) to fissile mudstone (Tyn-y-Twmpath Member). Formation has rich shelly (brachiopod) fauna. Includes Corwen Grit Member at top of formation. |
| Definition of Lower Boundary: |
Unconformable on various Caradoc Formations. |
| Definition of Upper Boundary: |
Top of Corwen Grit Member succeeded by pale grey-green siltstones and mudstones of the Fron Frys Formation. |
| Thickness: |
490 metres. Lateral variations, 320 - 490 metres. |
| Geographical Limits: |
Not defined. |
| Parent Unit: |
Not Applicable (-)
|
| Previous Name(s): |
Dolhir Beds
(-869)
|
| Alternative Name(s): |
none recorded or not applicable
|
| Stratotypes: |
| Type Area |
Wrexham, Sheet 121. |
| Reference(s): |
| Brenchley, P J. 1978. The Caradocian rocks of the North and West Berwyn Hills. Geological Journal, Vol. 13, 137-164. |
| Hiller, A, 1981. The Ashgill rock of the Glyn Ceiriog district, north Wales. Geological Journal, Vol.16, p.181-200. |
| 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: |
|
E120
E136
E150
E137
|
