Rock formation on Leckhampton Hill, south of Cheltenham, Gloucestershire, England
The Devil's Chimney is a rock formation on Leckhampton Hill, south of Cheltenham, Gloucestershire, England.
It is a largely man-made pillar outcrop, formed when an incline to a quarry was cut behind it, isolating the pillar from the main hillside. It is named for its peculiar shape, that of a crooked and twisted chimney rising from the ground. The Devil's Chimney is a local landmark, but its origins are uncertain. In 1926 it survived an earthquake, but not without a few cracks. In 1985 it was repaired and protected from further erosion.
Location.
The Devil's Chimney is on the western edge of the Leckhampton Hill Local Nature Reserve, which is part of the Cotswolds Area of Outstanding Natural Beauty. Leckhampton Hill has a history of extensive stone quarrying.
Local legend.
The outcrop was well-known as a local landmark by the time that Cheltenham was established as a popular tourist destination, although its true origin appears to have been forgotten already. Ruff's "History of Cheltenham" (1803) describes it as, "its grotesque chimney, built by preternatural hands" and "Built by the devil, as say the vulgar. It was no doubt built by shepherds in the frolic of an idle hour".
Legend holds that the Devil's Chimney is the chimney of the Devil's dwelling deep beneath the ground. Supposedly the Devil, provoked by the many Christian churches of the area, would sit atop Leckhampton Hill and hurl stones at Sunday churchgoers. However the stones were turned back on him, driving him beneath the ground and trapping him there so he could not further harass the villagers. Now he uses the mass of stones as his chimney to let free the smokes of hell.
Visitors to the Devil's Chimney would leave a coin on the rock as payment to the Devil in exchange for his staying in his underground home and not leaving to create mischief and spread evil in the local area.
Geology.
Leckhampton Hill comprises a flat-topped plateau, reaching a maximum height of 965 feet ASL. Four main horizontal rock strata form it. These are all limestones of the Middle Jurassic Inferior Oolite sequence. Below these are the Lias clays that form the valley floor. The Lower Lias form the valley floor, the marlstones of the Middle Lias form a prominent shelf that now carries the B4070 Birdlip Road which passes below the Chimney. The hill itself is formed of a series of limestones of similar age, but quite distinct appearance (from the base upwards): the lower limestones, pea grit, freestone and ragstones. There is also a variation in colour from a pale cream in the upper ragstones down to a russet brown at the base, owing to a higher iron content.
Heading uphill from the usual car park on Daisy Bank Road the lower slopes are planted with trees to stabilise them, where blocks of limestone slide downwards over the clays and then sands of the Lias acting as a weak lubricated layer. Some earthworks of the old tramways can be seen at this point, past lime kilns. 
Behind the lime kilns, a bed of the pisolitic Pea Grit forms a steeper but crumbly cliff. This is a distinctive and well-known exposure for the Cotswold oolites, which here form ovoid pisoliths the size of a pea. The mechanism of oolite formation is like that of a pearl, where material is progressively deposited around some initial seed fragment. In these rocks, the seeds have been identified as filaments of the algae "Girvanella pisolitica". 
Above the Pea Grits are two layers of freestone, separated by a band of oolitic marl, forming a series around thick, or deeper elsewhere in the area. Although all the limestones here have been quarried for lime burning, it was these freestones that formed the most valuable stone, and the main reason for quarrying at this location. These freestones, like those mined around Bath, were cut and worked 'green', i.e. still damp from the ground. As they dried out, a layer of calcium carbonate forms on the surface which has a protective effect against chemical erosion. Removing this layer accelerates erosion. The freestones show clear current bedding, although some examples are so pronounced that it could form a weak spot and make the stone less useful for stonemasonry.
The Chimney itself is formed from the lower freestone. Its flat top represents the upper surface of the lower freestone, and the transition to the marls that would not support any such narrow column.
Above the freestones are the ragstones, about thick. These split easily into flat pieces and are more easily quarried than the freestones, but were less valuable. They were used locally for dry stone walling and for building in rubble masonry or Neo Gothic styles, such as at St Pauls College. These ragstones are classed as shelly limestones, being fossiliferous with "Gryphaea" and "Trigonia" bivalves. Although the main plateau of the hill is at elevation, quarrying of the ragstone and upper freestone has been so extensive as to have formed a second plateau below this, around the perimeter of the hill.
The 19th-century geologist S. Buckman suggested that the strange shape of the Devil's Chimney could be put down to differential erosion, involving a softer outer rock being worn away to leave only the inner harder rock remaining. However there is no evidence for such a column of harder rock, nor an explanation for how it would form. The truth is probably that the Devil's Chimney was left behind by 18th-century quarry workers, who quarried around it as a joke.
Just to the South of the Chimney, the smaller workings of Salterley Grange Quarry form another exposure of the freestone. Movement of these rocks over the Pea Grit beneath has opened up much of their vertical jointing into fissures, some of which even show travertine deposits, although not in a commercially significant quantity. Some of the blocks between the fissures may, in time, separate sufficiently to indicae a possible formation mechanism for a column like the Chimney.
Quarrying.
Georgian Cheltenham was largely built with stone from the quarries of Leckhampton Hill. The oolitic limestone higher up the hill is a freestone of good quality for dressed stonework. Quarrying here was probably ancient, but it was expensive to transport the stone as the hill was too steep to allow stone to be carried by carts until it had been carried down to the Birdlip Road. The first industrial-era quarry began shortly after 1797 when the Cheltenham surgeon Charles Brandon Trye inherited the estate of Leckhampton Court. Soon afterwards, by 1803, he had constructed the first rope-worked incline from the road to the quarry atop the hill, passing just behind the Chimney. Bick dates the Chimney to before 1803 and reports that a Leckhampton antiquarian Alfred Bendall dated it to before 1795.
The Gloucester and Cheltenham Tramroad was formed in 1809 and included a branch southwards 2 3/4 miles to the foot of Leckhampton Hill, with Trye extending his tramway to join it, by constructing two more rope-worked inclines, Middle and Bottom, with a descent of 370 feet and a total length of 950 yards, costing Trye £1,900. These were designed by John Hodgkinson, the engineer of the Tramroad, who may also have designed the first incline. Although the utility of these new tramroads and inclines for the supply of building stone was welcomed in the "Cheltenham Chronicle" on their completion in April 1810, Trye did not live to see their benefits, as he died in 1811. After the opening of the tramroad, the price of dressed stone blocks in Cheltenham had dropped to just 1d per ton. 
Once the Tramroad was in operation, stone for Cheltenham was taken by that route and the original incline to the Birdlip Road was less important, and closed by about 1830. The quarries and inclines were still expanding though and another incline was constructed to the East, Top Incline. This may have re-used equipment taken from the closure of the original incline.
Conservation.
The outcrop is prone to erosion and by the 1960s had clearly visible signs of a likely collapse within 25–50 years. This was most noticeable on the exposed western side away from the hill, where a large vertical fissue was obvious.
Repair work was performed in the 1980s. This is most obvious in the lower section, which now resembles a man-made wall.
References.
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