Subterranean bridges might conjure images of Khazad-dûm in the Mines of Moria, where Gandalf faces the Balrog in The Lord of the Rings. Here on middle-of-the-road Earth, however, things are not quite so dramatic. Not quite, but nearly. In the bowels of underground abandoned mines, bridges of timber supported by rusting metal chains cross precipitous, abyssal gaps; yet mine explorers need no second invitation to brave them.
View from up top: Moel Fferna's Bridge of Death
The rotten planks of the legendary Bridge of Death in the Moel Fferna slate mine, North Wales straddle a heart-stopping drop, but this bridge is actually in better condition than most found in the Welsh slate mines. Even so, treading across to make it to the other side will earn you some well deserved kudos with the mine exploring community.
Subterranean Bridge of Death: Moel Fferna slate mine
This image shows another perspective on Moel Fferna's impressive Bridge of Death, which spans the roof of a large, high vaulted chamber. A scarcely visible tramline runs along the chamber floor, where the silhouette of a mine explorer can be seen. Moel Fferna is a rare case of a slate mine where there is no trace of surface workings; they were all completely underground.
Rotten bridge beneath the surface: Bleanau slate mine
Emerging from the claustrophobic confines of a derelict mining tunnel only to find yourself faced with a bridge that looks as though it might collapse at any moment is not an experience for the fainthearted. This next bridge is not even safe to set foot on, so decayed is it by the clawing hand of time: climbing ropes fixed to the rock face on one side were needed to traverse the uncertain gap it spans.
Into the unknown: A mine explorer clings to the wall while darkness looms ahead
The exact location of these next few bridges must remain unspecified because they were photographed before gaining access to the tunnel network in which they lie became an issue. Suffice to say that at their peak in the 19th century, the combined quarries produced well in excess of 50,000 tonnes of slate each year and together represented one of Britain's biggest.
Rickety crossing: Another bridge in a mine system that must remain nameless
In fact, in its heyday north-west Wales was home to the largest slate mines and quarries in the world, and the slate industry dominated the economy of the region until decline set in at the beginning of the 20th century. The Great Depression sandwiched by two World Wars saw the closure of many smaller quarries, while competition from other roofing materials led to the larger ones being shut down in the 1960s and '70s.
Underground Bridge of Death: Croesor Quarry slate mine
Croesor is another Welsh slate quarry that lies almost entirely underground. Despite a series of collapses, it is possible to make the trip from Croesor to the nearby Rhosydd Quarry via a tunnel. Home-made bridges, fixed ropes, zip wires and even inflatable boats have been installed to make this classic mine explorers' trip possible, if not necessarily safe. These pictures show the final and most awkward crossing – another ‘Bridge of Death’.
Making the crossing: Ropes help explorers over Croesor's timber bridge
Why are these bridges such a feature of Wales’ long disused slate mines? Well, where the slate was worked away below the main haulage floor, building a wooden bridge across the hollowed out chamber maintained it as a through way. Often suspended from chains fixed into the roof above, these bridges could be as much as 100ft (30m) above the floor below; high enough to let giddiness set in after a brutal day's work at the rock face.
Chamber of Horrors: Remains of bridge across a double chamber in Croesor
The image above is another stage in the Croesor-Rhosydd through trip, affectionately dubbed The Chamber of Horrors. As photographer Simon Lowe told Environmental Graffiti: "This bridge was unusual in that it spanned a double chamber and as the photo shows would have rested on the quarried away wall". The bridge supports still exist, doing a bad impression of a trapeze, while the partially worked away wall separating the chambers can be seen on the right.
Floating bridge: Beams of a bridge over freezing water in Croesor
The water in these underground cavities may look inviting, but be deceived ye not: it's deathly cold. Mine explorers must not only wrestle with claustrophobia and vertigo; when negotiating bridges that don't teeter over dizzying drops, the prospect of water at temperatures that could quickly bring on hypothermia may await. Above, the metal beams of a bridge over a flooded chamber in Croesor beckon the sure-footed. We'll leave it to the mine explorers and Gandalfs of this world.
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