Douglas Blane meets the coal museum guides who used to mine the seams.
In a lush tropical forest, water drips from giant fronds on to the forest floor. Strange reptiles and insects crawl and slither on the marshy ground, where leaves and trees that once reached up to the sun have fallen. Eventually a dead forest accumulates beneath the living one and millions of years of heat and pressure turns it to black stone.
Time passes. In the petrified forest people of all ages crawl and slither. They hack at the black stone and carry it to the surface. After a while only men work underground, joined by mighty machines that chew through rock. When the men leave, silence and darkness take over.
Above, in the sunshine, a few of the men tell the story of coal to children in bright orange helmets. The Lady Victoria Colliery at Newtongrange has become the Scottish Mining Museum.
"Even after coalmining was mechanised," says tour guide Billy Whitson, "it was brutal - three shifts a day under intense pressure to get the coal out, sometimes in horrific conditions. Water broke in at the last mine I was at and the men were up to their chests in it, working to save the mine.
"When I was in my fifties they started a consortium at Monktonhall pit and I said I wouldn't join, but the lure was too strong and I went back. It was the comradeship. If you're brought up in a mining environment there's nothing like it."
Grants worth pound;5 million have recently been spent on redeveloping the museum. In addition to the guided tour of the colliery and a chance to operate the massive winding engine, visitors now get a trip along an underground roadway to a simulated coalface and two major exhibitions which tell the story of coal and the people who extracted it, from earliest times to the modern day.
"I gang to work at four in the morning until five at night," comes the voice of a young lad of the 1840s, while a primary 7 class from Drumbrae school, Edinburgh, listens with rapt attention. "I work every day. It's gey drippy, soul-crushing work. I've forgotten all my letters. I'd like to go to school but I cannae.
"The improvements are great," says teacher Julia Higgins. "I bring a class here every year - it's part of our school curriculum on the Victorians - and before we come I talk about the people and the work. It's only when they get here that they appreciate what the conditions were really like."
One of the new developments at the museum is the Operations Centre, where experiments on gears and pulleys, cutting coal, pumping water, mine ventilation, mechanical structures and combustion, provide children with insights into the science and technology of coalmining.
The exhibitions are varied, fascinating and informative; the reconstructions are convincing ("but we had to turn the noise at the coalface down a bit, because it frightened some of the visitors"). But the museum's most valuable asset is probably the tour guides - eight fit and friendly miners with 250 years experience between them.
"As soon as our guide started talking the children focused on him," says Mrs Higgins. "This was someone who had been a miner, and he had so much to tell them that brought it alive. They are a resource that is going to be missed when they retire."
"The youngest of us is 59," says Mr Whitson. "Just a laddie. We all enjoy it here, talking to the visitors and working with miners again." He laughs. "In our minds we're still digging coal."
At the peak of production 148,000 coalminers, who with their families made up 10 per cent of Scotland's population, were extracting 43 million tonnes of coal a year from more than 200 pits. Today Longannet in Fife, which produces two million tonnes a year, is the only deep mine in Scotland.
"There are those," concludes the commentary, "who believe that coal will recover strongly as stocks of other fossil fuels are used up. Who knows? What we do know is that Scotland's prosperity was built on coal, on mines like this, and on the skills and labour of Scotland's miners."
The Scottish Mining Museum, Newtongrange, Midlothian EH22 4QN.
Tel: 0131 663 7519.
www.scottishminingmuseum.com Open daily. pound;2 per child, teachers free. Teachers' pack.