| Computer Code: |
RRLO |
Preferred Map Code: |
RRL |
| Status Code: |
Full |
| Age range: |
Bolsovian Substage (CC)
— Bolsovian Substage (CC) |
| Lithological Description: |
Olivine basalt to microgabbro (dolerite) with phenocrysts of altered olivine and subordinate augite and/or plagioclase that commonly form glomerophyric masses. The groundmass displays ophitic or subophitic texture. Listric cooling joints are pervasively developed. |
| Definition of Lower Boundary: |
Sharp boundary seen in Hailstone Quarry [SO 9665 8835]. Basal 0.5 m of dolerite comprises joints sub-parallel with an igneous lamination and the basal boundary. Above this near vertical cooling joints are developed. Below the sharp boundary the Etruria Formation country-rock comprises 1.5 m of sandstone, underlain by black, hardened mudstone. |
| Definition of Upper Boundary: |
Sharp boundary formerly seen in Darby's Hill Quarry [SO 9683 8962]. About 1.6 m of finely crystalline microgabbro (dolerite) overlain by 1.8 m of unbaked red, mottled silty mudstone of the Etruria Formation. |
| Thickness: |
Up to 100 m. |
| Geographical Limits: |
Rowley Regis, southwest of Oldbury. Extends for about 3 km from Darby's Hill [SO 966 899] in the north to Hawes Hill [SO968 868] in the south. Also, isolated area around Tansley Hill [SO 956 894]. |
| Parent Unit: |
Brierley Hill Cluster (BRIER)
|
| Previous Name(s): |
Rowley Regis Laccolith
(-5009)
|
| Alternative Name(s): |
none recorded or not applicable
|
| Stratotypes: |
| Type Section |
Hailstone [SO 966 882] and Edwin Richards [SO 968 884] quarries, Rowley Regis. Sharp boundary seen in Hailstone Quarry [SO 9665 8835]. Prominent listric joints evident within both quarries. Described by Powell et al. (2000). |
| Reference(s): |
| Powell, J H, Glover, B W and Waters, C N. 2000. Geology of the Birmingham area. Memoir of British Geological Survey Sheet 168 (England and Wales). |
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: |
|
E168
E169
|
