| Computer Code: |
LLC |
Preferred Map Code: |
notEntered |
| Status Code: |
Full |
| Age range: |
Emsian Age (DE)
— Emsian Age (DE) |
| Lithological Description: |
Red sandstones, siltstones and mudstones with beds of pebbly sandstone and conglomerate containing exotic pebbles sourced from the south; common calcrete profiles. |
| Definition of Lower Boundary: |
At base of lowest conglomerate with exotic pebbles (extraformational conglomerate), which overlies mudstones/siltstones/sandstones and intraformational conglomerates of the St Maughans Formation. |
| Definition of Upper Boundary: |
At the appearance of drab brown sandstones of the Brownstones Formation, which on the M4 Motorway Pantmawr cutting [ST 1487 8219] lies 5.6 m from the top of the highest bed of extraformational conglomerate, where the junction is sharply defined. |
| Thickness: |
About 137 to 150 m. |
| Geographical Limits: |
South and south-west of Machen, Monmouthshire; in the Cardiff district in the core of the Cardiff - Cowbridge Anticline, north-west limb of the Rogerstone Anticline and in two fault-bounded inliers at Michaelston-super-Ely and Drope. |
| Parent Unit: |
Milford Haven Subgroup (MIH)
|
| Previous Name(s): |
none recorded or not applicable
|
| Alternative Name(s): |
St Maughans Formation [Obsolete: use FWW]
|
| Stratotypes: |
| Reference Section |
Stream section in Nant Cwm Crynant [ST 2040 8565].
Type section at Railway cutting at Llanishen station, grid reference not given, Squirrell and Downing, 1969. |
| Reference(s): |
| Heard, A and Davies, R. 1924. The Old Red Sandstone of the Cardiff district. Quarterly Journal of the Geological Society, Vol.80, 489-519. |
| Squirrell, H C and Downing, R A. 1969. Geology of the South Wales Coalfield, Part 1, the country around Newport (Monmouthshire). Memoir of the Geological Survey of Great Britain, Sheet 249 (England and Wales). |
| Waters, R A and Lawrence, D J D. 1987. Geology of the South Wales Coalfield - Part III: the country around Cardiff. Memoir of the British Geological Survey, Sheet 263. (England and Wales). |
| Allen, J R L. 1975. Source rocks of the Lower Old Red Sandstone: Llanishen Conglomerate of the Cardiff area, South Wales. Proceedings of the Geologists' Association, Vol. 86, 63-76. |
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: |
|
E263
E262
|
