Browsing the Internet on my mobile telephone one evening, my eyes stopped on the following passage on the Wikipedia entry for Castleton:
Castleton used to be on the A625 road from Sheffield to Chapel-en-le-Frith, on the way to Manchester. Leaving Castleton, the western road used to go over Mam Tor, but after continual collapses and repairs (Mam Tor is called the 'Shivering Mountain' because of its very loose shales) it was eventually abandoned.
Did someone mention an abandoned road?
The above map shows the area around Castleton as is was nearly half a century ago, as recorded in the ever-fascinating AA Book of the Road 1966 edition. You can clearly see that the main road through Castleton is called the A625. The route from Sheffield, through Hathersage, continues to Chapel-en-le-Frith.
But what's this? The current map as depicted by Multimap shows no sign of the A625. Instead, the route through Castleton is labelled the A6187, and takes a different route to the west of the village. Look, no kink!
The explanation is that kink, or rather, the ground upon which it lay. The original 19th Century route from Castleton to the west threaded though Winnats Pass, a difficult mile long 1 in 5 climb between two pillars of rock. In 1847 the Manchester & Sheffield Turnpike Company decided to bypass this route, and built a more gentle road up the western slopes of nearby Mam Tor.
I don't know if the 1,700ft peak was known as the Shivering Mountain in 1847, but if t was the Manchester & Sheffield Turnpike Company missed a vital clue as to the certain failure of their project. The above southerly view shows a shady scar, known as the Mam Tor Landslide. This is essentially a 4,000 year old landslip, which when last measured ten years ago was found to be still moving at an average annual rate of 25cm.
The instability of the ground, plus the increasing amount of traffic (especially heavy lorries from the mid-20th century) resulted in major repairs being required in 1912, 1933, 1946, 1952, and 1966. In 1974 and 1977 major landslides put the road out of action for many weeks at a time; after the latter event some sections were reduced to single carriageway.
But keeping the road open was always going to be a Sisyphean task, and Derbyshire County Council recognised they were fighting losing battle in 1979. Interestingly, they chose to simply abandon the road that crossed the landslip area (just half a mile or so of tarmac) from the hairpin bend just beyond the disused Odin Lead Mine to Blue John Cavern at the top of the hill. The road was re-numbered in the year 2000; the new A625 turns south-west just before Hathersage, and joins the A623 beyond Froggatt.

The map above is the most recent Ordnance Survey map of the area. Compare this to an Ordnance Survey from around 1930 (below), and one from 1899 (double below).
And now I suppose you might like to see some pictures? Well, seeing as you've been good enough to read this far...

Gemma and me at the bus turning circle, near Blue John Cavern. This is the end (or start) of the road at the top of Mam Tor. It was a little windy.

I walked about two-thirds of the way down the road. Here is the view of the hairpin bend, just before a major section of missing road. I was amazed at how in places, the road just wasn't there; the asphalt and foundations had simple crumbled into tiny pieces and dribbled down the hill.

From the same spot, looking uphill. Note the massive steps in the road, which here is slipping down towards the bottom-left of the picture.

A little further up the hill, looking down towards Mam Farm. See how the Chapel-bound carriageway has dropped around four feet, and has then been swaddled in ballast washed out from under the Castleton-bound lane.
Below are a trio of views towards Castleton. You might just be able to make out the out-of-place cement works in the first two.



Here's my beautiful girlfriend sat on the above 'step'.

Next, a downhill view from the same step (check out the white lines still in evidence), and then a close-up of the large crack.



The same step, again from below, models unknown. Even cyclists are forced to dismount at this point.
Finally, look at this hole. JUST LOOK AT IT!
I thought that we'd have the place to ourselves, but there were plenty off people walking and cycling on this thirty-one year old tarmac corpse. I wonder what it will be like in another thirty-one years, and how long nature will take to erase any trace of the old A625. I don't feel like the Shivering Mountain is under any obligation to rush.