Geology of the Bath area: Applied geology: mineral resources
|This topic provides a summary of the geology of the Bath area – covered by the British Geological Survey
1:50k geological map sheet 265.
Authors: A J M Barron, T H Sheppard, R W Gallois, P R M Hobbs and N J P Smith (BGS).
A detailed account of the history of coal mining in the region is given by Cornwell (2003), from which much of the following is taken. Colliery names in bold are shown on the published 1:50 000 geological map. The earliest workings for coal are in the Coalpit Heath Syncline, where mining was underway by the 1680s, and steam-powered pumps were in use by the mid 18th Century. Mines such as the Half Moon [680 811], Oxbridge [681 815] and Upper Whimsey [678 807] pits were working seams in the Grovesend Formation, principally the High Coal. Larger pits at Ram Hill [679 803] and Serridge [675 796], located further south, were operating by 1790. The last colliery in the Coalpit Heath syncline was the Coalpit Heath Colliery, worked from the Frog Lane Pit [687 816], which was sunk in the early 1850s. The Hard, Top and High coals were all worked, but the colliery was abandoned in 1949. In the Mangotsfield area, the Brandy Bottom (Parkfield South) Colliery [682 772] had two shafts, one nearly 200 m deep. To the north-east, the Parkfield Colliery [689 778] had nine shafts, and was one of the most successful in the area. Both Parkfield and Brandy Bottom worked coals in the Grovesend Formation, and both were closed in 1936.
Mining was very extensive in the area of the Kingswood Anticline on the crop of the more productive South Wales Middle Coal Measures Formation. The oldest workings are bell pits dating back at least to 1680. Major pits include the very early Soundwell colliery [659 750], which had several shafts, and worked a number of coals in the Middle Coal Measures, including the Five Coals, the Kingswood Great Coal and the Soundwell Hard Venture Coal. The lowest seam known in the district was worked at Soundwell, but following accidents and flooding it was closed in 1853.
To the south, the Siston Common (or Syston Hill) Colliery [669 739] opened around 1790, but it worked complex, faulted ground and was closed by 1889. The Crown Colliery [672 735] was sunk around 1820, and faced similar difficulties. The Goldney Pit [670 726] at Cadbury Heath was opened at about the same time, mining seams around the level of the Coking Coal and the New Smith’s Coal. Further south, workings were largely undertaken in the Pennant Sandstone Formation. The California collieries [665 716] exploited the Millgrit, Chick and Hen Coals from 1875, but an inrush of water in 1904 led to their closure. In the Bitton area, the New [686 710] and Old [690 708] Golden Valley collieries were the deepest workings within the district, extending to a depth of some 625 m to work the upper parts of the South Wales Middle Coal Measures Formation.
Away from the main coalfield, a limited number of coal workings have been undertaken in the district around Bath. These include a trial shaft at Batheaston [7820 6750] and the Pennyquick (or Twerton No. 1) Colliery [715 646], which worked the Lower Five Coal and others in the South Wales Middle Coal Measures Formation at depths between 109 and 260 m.
Metalliferous mineralisation is scarce in the Bath district, and largely confined to replacive bodies of hematite (iron ore) found along faults and fractures in the Carboniferous rocks. They have only been worked in the region of the Coalpit Heath Syncline, around Frampton Cotterill. Iron ore was also worked in the Parkfield area of Pucklechurch at the end of the 19th century.
- Cornwell, J. 2003. The Bristol Coalfield. (Ashbourne, Derbyshire: Landmark Publishing.)