Slaley Sough

Overview

Slaley Sough, on Bonsall Leys, was driven from 1740 to drain the Great Rake before a costly 1850s extension along Parsons Rake; properly known as Bonsall Leys No. 2 Level, its long inner passage remains dry today thanks to an overlying layer of toadstone.

History

Slaley (or Slayley) Sough, built around 1740-1790 and first mentioned in April 1749, was driven beneath the Matlock lower lava to reach the Bonsall Lees Great Rake; its 18th-century course ran for 220 metres. It was extended between 1854 and 1859 for a further 600 metres along Parsons Rake, principally by the Bonsall Lees Mining Co., at a cost of £1,325 -- though the extension did find better ore. A section of the sough dated 1854 is held by the Derbyshire Record Office. Properly known as Bonsall Leys No. 2 Level, the sough was described in detail by R. B. Flindall and A. J. Hayes in a 1971 Peak District Mines Historical Society Bulletin article on the adit workings north of the Via Gellia. Its later, larger passage includes a 150-foot blind rise known to spar miners of the 1950s as the Thunder Shaft, on Flixen Rake -- blind even when first sunk, despite an original assumption that its raises continued to the surface. The extension was funded by investors drawn in during the speculative mining boom that followed the mid-1850s Limited Liability Acts, when local tradesmen took small shares in ventures as a form of gambling; unlike some contemporary schemes at Matlock, which tended toward fraud, those at Bonsall were, in one historian's words, 'blindly optimistic' rather than dishonest. The overlying toadstone keeps the workings unusually dry for a drainage sough, though a faint sound of running water -- its source never identified -- can be heard through a narrow rift in one wall not far from the sough's final forefield.

Geology

A drainage sough driven through solid, unusually dry ground beneath a layer of toadstone (basalt), reaching the Great Rake and, in its 1850s extension, Parsons Rake and Flixen Rake.

Workings

A long coffin-level drainage sough (properly Bonsall Leys No. 2 Level), including a 150ft blind rise (Thunder Shaft) on Flixen Rake, extended in the 1850s at a cost of £1,325.

Closure

No definite closure date was found in the sources read for this pass; the 1850s extension appears to be the last significant phase of work recorded.

What remains

Accessible via a small, awkward entrance level; explored and discussed by cavers into the 2010s, with its raises and side workings not all confirmed as fully explored.

A roadside entrance survives in the Via Gellia (Bonsall Leys No. 1 Level); old 18th-century surface shafts intersected by the sough are recorded but largely blocked.

Nearby mines

• Haslowfield Mine — 0.4 km SW
• Good Luck Mine — 0.6 km SW
• Via Gellia Lead Mines — 0.6 km SW
• Bondog Hole Mine — 1.3 km SW
• Hopton Wood Quarries and Middleton Mine — 1.5 km S

Straight-line distance, within 15 km. Show on the map.

What's uncertain

Points where sources disagree or the record could not be settled; both accounts are kept. All open questions in the archive.

• The sough's 1850s extension was funded by investors drawn in by the speculative mining boom following the mid-1850s Limited Liability Acts; ventures at Bonsall in this period were 'blindly optimistic' rather than fraudulent, unlike some contemporary schemes at Matlock. (uncertain) ²

Recorded claims

Individual factual claims, each attached to the source(s) that support it below. Where sources disagree, both are kept.

• Slaley Sough, built c.1740-1790 and first mentioned in April 1749, was driven beneath the Matlock lower lava to the Bonsall Lees Great Rake (220m in its 18th-century form), and was extended 1854-59 for a further 600m along Parsons Rake, principally by the Bonsall Lees Mining Co., at a cost of £1,325. ¹
• Properly called Bonsall Leys No. 2 Level, the sough was described by R.B. Flindall and A.J. Hayes in a 1971 PDMHS Bulletin article; its later passage includes a 150ft blind rise on Flixen Rake known as the Thunder Shaft, which was blind even when first sunk. ²
• The sough's 1850s extension was funded by investors drawn in by the speculative mining boom following the mid-1850s Limited Liability Acts; ventures at Bonsall in this period were 'blindly optimistic' rather than fraudulent, unlike some contemporary schemes at Matlock. (uncertain) ²

Photographs & further reading

Sources

1. (primary) Derbyshire HER: Slaley Sough, Bonsall (MDR3104) — Derbyshire Historic Environment Record
2. (observational) Slaley Sough (forum thread) — UK Caving forum (contributor History Trog, author of the 1971 PDMHS Bulletin article on the site)

Record created: 16 September 2026 · Last researched: 16 September 2026