| Computer Code: |
CYH |
Preferred Map Code: |
CYH |
| Status Code: |
Full |
| Age range: |
Ludlow Epoch (SU)
— Ludlow Epoch (SU) |
| Lithological Description: |
Interlaminated and very thinly interbedded grey silty mudstone, siltstone/fine-grained sandstone and carbonaceous (anoxic) hemipelagite; disruptive bioturbation negligible. |
| Definition of Lower Boundary: |
Disappearance of thick mudstone turbidite units of underlying undifferentiated Bailey Hill Formation. |
| Definition of Upper Boundary: |
First appearance of significant disruptive bioturbation, indicating onset of oxic bottom conditions. |
| Thickness: |
Up to 220m thick. |
| Geographical Limits: |
Dies out southwards; southern limit at c. (SO 158 795); northwards extends at least as far as (SO 120 850). |
| Parent Unit: |
Bailey Hill Formation (BAI)
|
| Previous Name(s): |
none recorded or not applicable
|
| Alternative Name(s): |
Approximately Equivalent To The Monograptus Leintwardinensis Shales.
|
| Stratotypes: |
| Type Section |
Track section north-east of the old (now abandoned) Cwm-yr-hob farmhouse, Felindre, Powys. |
| Reference Section |
Lyrychyn Quarry, Cilfaesty Hill. |
| Reference(s): |
| Cave, R, and Hains, B A. 2001. Geology of the country around Montgomery. Memoir of the British Geological Survey, Sheet 165 with part of 151 (Welshpool) (England and Wales). |
| Earp, J R. 1938. The higher Silurian rocks of the Kerry district, Montgomeryshire. Quarterly Journal of the Geological Society of London. Vol. 94/1, 125-160. |
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: |
|
E165
|
