| Computer Code: |
BRBE |
Preferred Map Code: |
notEntered |
| Status Code: |
Full |
| Age range: |
Late Devonian Epoch (DU)
— Tournaisian Age (CT) |
| Lithological Description: |
none recorded or not applicable
|
| Definition of Lower Boundary: |
The lower boundary of the group is placed at the base of the lowest bed that overlies the regional Acadian unconformity. A change of colour from red sandstones below the unconformity to pale green or buff sandstones above is common. |
| Definition of Upper Boundary: |
The upper boundary of the Old Red Sandstone (and of the Upper Old Red Sandstone) is placed generally at the top of the highest red bed of terrestrial facies, and at the base of limestones and mudstones of the Avon Group of the Carboniferous Limestone Supergroup, which mark the marine transgression in the early Carboniferous and the inception of shallow marine carbonate sedimentation. |
| Thickness: |
In Wales, the thickness of the group ranges from 45 m on the south-east crop of the South Wales Coalfield to 350 m in the Pembroke peninsula. A maximum thickness of 490 m occurs east of the Severn Estuary. |
| Geographical Limits: |
Widely distributed in the Pembroke Peninsula, the periphery of the South Wales Coalfield, Forest of Dean, Bristol district and the Mendips, along with an outlier in the Clee Hills and an inlier at Merevale, Warwickshire; also present at depth in southern and eastern England south of Cambridge. |
| Parent Unit: |
Old Red Sandstone Supergroup (ORS)
|
| Previous Name(s): |
Upper Old Red Sandstone Group
(ORSU)
|
| Alternative Name(s): |
none recorded or not applicable
|
| Stratotypes: |
| Type Area |
Brecon Beacons, Powys [SO 042 215]. |
| Reference(s): |
| Barclay, W J, Davies, J R, Hillier, R D, and Waters, R A. 2015. Lithostratigraphy of the Old Red Sandstone successions of the Anglo-Welsh Basin. British Geological Survey Research Report, RR/14/02. 96pp. |
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: |
| none recorded or not applicable |
