[1] Its coal seams were formed from the vegetation of tropical swampy forests in the Carboniferous period over 300 million years ago.
The Romans may have been the first to use coal in Lancashire and its shallow seams and outcrops were exploited on a small scale from the Middle Ages and extensively after the start of the Industrial Revolution.
The coalfield was at the forefront of innovation in coal mining, prompting the country's first canals, use of steam engines and creating conditions favourable for rapid industrialisation.
The coal measures were subsequently subjected to folding; this accounts for the dip towards the south and west; faulting occurred at that time.
The Red Rock Fault skirts the north-west extremity of the North Staffordshire coalfield towards Macclesfield and Poynton Colliery in Cheshire.
The coalfield covers around 550 square miles (1,400 km2) extending from Stalybridge in the southeast to Ormskirk in the northwest and from Rainhill in the southwest to beyond Burnley in the northeast.
[12] John Leland visited Haigh in 1538 and observed that "Mr Bradshaw ... hath founde moche Canel like Se coal in his grounde very profitable to him.
[19] In 1600 the collieries were drifts where coal outcropped, and shallow bell or ladder pits where roof falls were common and poor drainage led to them being abandoned.
[20] Other soughs were dug, including one in 1729 to drain the Worsley mines and another from Standish Colliery to the Leeds and Liverpool Canal at Crooke.
A waterwheel was used from 1720 to lift water from the workings of the Plumbe Street Mine in Burnley using an endless chain of buckets, and James Brindley installed one at the Wet Earth Colliery in the Irwell Valley.
In the following 20 years the main lines of the railway system were constructed, linking the increasingly industrial towns in Lancashire with the rest of the country.
Providing fresh air and removing firedamp from pits with a single shaft was a problem as explosive gases accumulated.
The air flow was improved by braziers or fire baskets suspended in the shaft, and by the late 1700s underground furnaces, in combination with stoppings and doors.
[28] At the turn of the 19th century demand for coal increased rapidly for domestic and industrial consumption: steam was used to power factories and steamships.
Children as young as five sat in complete darkness opening ventilation doors for "hurriers", women and boys who hauled tubs of coal to the shaft bottom.
Some coal owners, including William Hulton, paid their workers with tokens or vouchers that could only be redeemed in their company shops, a practice outlawed by the Truck Act 1831.
The Duke of Bridgewater paid eight shillings (40p) for a six-day working week with shifts of 12 to 15 hours and fined those who were late half a crown.
William Hulton reputedly paid the poorest wages in Lancashire and was hostile to permitting his workforce the right to free assembly.
[19] The Mining Industries Act of 1925 attempted to stem the post-war decline and encouraged independent companies to merge in order to modernise and better survive the economic conditions of the day.
At the same time, the NCB embarked on an extensive programmes of boring to prove the reserves of coal, and modernised existing collieries.
[39] In the 1960s the NCB began closing collieries, some with workable coal reserves, by setting impossible production targets and by 1967 just 21 pits remained.
Mining was dangerous: flooding, gases, roof falls and explosions of firedamp contributed to the deaths of thousands of workers in Lancashire's pits.
The third worst mining disaster in the country was at Hulton Colliery Company's Pretoria Pit in 1910 when a faulty lamp caused an explosion killing 344 miners.
The employers arbitrarily fined men for minor reasons, disallowed wages on false pretexts and victimised perceived radicals.
[40] Lancashire was at the forefront of innovation in coal mining from James Brindley's 1756 water wheel at Wet Earth Colliery to the Duke of Bridgewaters's underground canals.
[46] Lancashire had the first pithead baths in the country at Gibfield Colliery in Atherton and the first mines rescue station to cover an entire coalfield at Howe Bridge in 1908.
[48] Hindley lies in the centre of the great Lancashire coalfield, and consists of a level-surfaced country dotted over with collieries and black pit-banks.
A close network of tramways and railways covers the face of a singularly dreary stretch of country, where the pastures are scanty and blackened.
What trees remain standing appear as dead stumps, with leafless branches reflected weirdly in the 'flashes' of water.Coal mining has left areas of derelict land and spoil heaps or "rucks" across the coalfield.
[50] The Astley Green Colliery Museum and Gin Pit Miners Welfare in Tyldesley are two of the last tangible reminders of the once thriving industry.