| Computer Code: |
LORS |
Preferred Map Code: |
LORS |
| Status Code: |
Full |
| Age range: |
Early Devonian Epoch (DL)
— Early Devonian Epoch (DL) |
| Lithological Description: |
[Obsolete: use DAUG]
The coarsening-upwards succession comprises red floodplain mudrocks, with common calcrete, and sandstones ranging from high-sinuosity channelised deposits to low-sinuosity, braided stream deposits, the latter including sheet flood sandstones and laterally accreted sandbodies. These represent increasingly proximal alluvial deposition, culminating in coarse conglomerate fan deposits locally. |
| Definition of Lower Boundary: |
The base of the group is placed at the appearance of red beds in the late Silurian. In the Marloes peninsula of south-west Pembrokeshire, the base of the group is placed at the conformable junction of the tidal deposits of the Gray Sandstone Group and the overlying Red Cliff Formation. Elsewhere, the base of the group is traditionally placed at the base of the Ludlow Bone Bed, a thin, lenticular phosphatised lag deposit at the base of the littoral Downton Castle Sandstone Formation. |
| Definition of Upper Boundary: |
The upper boundary is a major regional unconformity, above which Upper Devonian rocks of the Upper Old Red Sandstone Group overstep the Lower Old Red Sandstone Group. |
| Thickness: |
The Lower Old Red Sandstone Group is up to 4200 m thick in the Pembroke peninsula and up to about 2000 m thick elsewhere. |
| Geographical Limits: |
At outcrop in the West Midlands [e.g. Clee Hills SO 58 83], Welsh Borderland [e.g. Ludlow SO 45 75] and southeast [e.g. Monmouthshire SO 41 07], south central Wales [e.g. Brecon Beacons SO 04 21] and Pembrokeshire [e.g. SS 02 98]. |
| Parent Unit: |
none recorded or not applicable
|
| Previous Name(s): |
none recorded or not applicable
|
| Alternative Name(s): |
none recorded or not applicable
|
| Stratotypes: |
| none recorded or not applicable |
| Reference(s): |
| Waters, C N, Gillespie, M R, Smith, K, Auton, C A, Floyd, J D, Leslie, A G, Millward, D, Mitchell, W I, McMillan, A A, Stone, P, Barron, A J M, Dean, M T, Hopson, P M, Krabbendam, M, Browne, M A E, Stephenson, D, Akhurst, M C, and Barnes, R P. 2007. Stratigraphical Chart of the United Kingdom: Northern Britain. (British Geological Survey.) |
| 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. |
| 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: |
|
E246
E251
E005
E236
S109
S109
S115
S115
S087
|
