[1] The Coal Measures lie above a bed of Millstone Grit and are interspersed with sandstones, mudstones, shales, and fireclays and outcrop in the Oldham district.
The Gannister Beds or Lower Coal Measures occupy the high ground of the West Pennine Hills above Oldham where the most productive seam is the Mountain mine.
[5] In A tour thro' the whole island of Great Britain finished in 1727, Daniel Defoe described "...Coals...upon the top of the highest hills" around Oldham.
[6] Exploitation of the local coal seams led to the rapid development of early steam-powered cotton mills and 65 had been built in Oldham by 1825.
[7] The early collieries were adits, accessing the coal from outcrops on the side of a hill at Crompton Moor, Oldham Edge and Werneth, employing up to a dozen workers.
James Watt installed a Newcomen steam pumping engine at the company's Fairbottom Colliery in the late 18th century.