Midlothian Coalfield
The Midlothian Coalfield is a coalfield in southeast Scotland situated immediately to the east and southeast of Edinburgh. It is geologically continuous with the East Fife Coalfield beneath the Firth of Forth though the undersea coal reserves have only been partly exploited. There were undersea workings extending from Prestonlinks Colliery. The sulphur content of the majority of Midlothian coals is less than 1% making it especially suitable for modern requirements. Geology. The following seams were worked. They are shown in rough stratigraphical order thought not all seams are present throughout the coalfield. Those shown in bold were worked  to the greatest extent: Within the Scottish Coal Measures Group (Middle and Lower Coal Measures): Within the Upper Limestone Formation: Within the Limestone Coal Formation: Within the Lower Limestone Formation Within the West Lothian Oil-Shale Formation Monktonhall Colliery was abandoned in 1997 and Blinkbonny mine adit was sealed in 2003 so bringing to an end a long history of deep-mining of coal within the coalfield. Opencasting has continued at various sites since then including Blinkbonny, Oxenfoord, Gourlaw and Newbigging Farm.