Scheduled Monument: SLACK, MOUNT PLEASANT AND BARMASTERS GROVE LEAD MINES, 390M SOUTH EAST OF BLAKELOW FARM (1019042)

REASONS FOR DESIGNATION Approximately 10,000 lead industry sites are estimated to survive in England, spanning nearly three millennia of mining history from the later Bronze Age (c.1000 BC) until the present day, though before the Roman period it is likely to have been on a small scale. Two hundred and fifty one lead industry sites, representing approximately 2.5% of the estimated national archaeological resource for the industry, have been identified as being of national importance. This selection of nationally important monuments, compiled and assessed through a comprehensive survey of the lead industry, is designed to represent the industry's chronological depth, technological breadth and regional diversity. The ore works were an essential part of a lead mining site, where the mixture of ore and waste rock extracted from the ground were separated (`dressed') to form a smeltable concentrate. The range of processes used can be summarised as: picking out of clean lumps of ore and waste; breaking down of lumps to smaller size (either by manual hammering or by mechanical crushing); sorting of broken material by size; separation of gravel sized material by shaking on a sieve in a tub of water (`jigging'); and separation of finer material by washing away the lighter waste in a current of water (`buddling'). The field remains of ore works include the remains of crushing devices, separating structures and tanks, tips of distinctive waste from the various processes, together with associated water supply and power installations, such as wheel pits and, more rarely, steam engine houses. Simple ore dressing devices had been developed by the 16th century, but the large majority of separate ore works sites date from the 18th and 19th centuries, during which period the technology used evolved rapidly. Ore works represent an essential stage in the production of metallic lead, an industry in which Britain was a world leader in the 18th and 19th centuries. Sites are common in all lead mining areas and a sample of the best preserved sites (covering the regional, chronological, and typological variety of the class) will merit protection. The remains of Slack, Mount Pleasant and Barmasters Grove lead mines 390m south east of Blakelow Farm are well preserved and include a number of components relating to the mining of these veins. They have particularly early origins and will retain significant information about early lead working. The standing, earthwork, buried and rock cut remains combined with the documentary sources provide evidence for both the historical and technological development of what was once a far more extensive, multi-period mining landscape. They incorporate a wide range of mining and processing features, which enable the development of the mine working and its chronological range to be reconstructed. The large veins, smaller scrins, shafts, hillocks and other extraction features provide evidence for methods of extraction whilst other processing areas will contain deposits showing the effectiveness of these techniques. The mining remains also provide an insight into the Derbyshire Barmote Court system of mining and the constraints this imposed on the miners of the area. DETAILS The monument includes the earthwork, buried, standing and rock cut remains of Slack, Mount Pleasant and Barmasters Grove lead mines 390m south east of Blakelow Farm. The monument is situated on Bonsall Moor, between Bonsall Lane and Tower Lane. Geologically, the monument lies to the north of the Great Bonsall Fault, with the lead veins running through gently folded limestone and lying at a stratigraphic horizon beneath the Matlock Lower Lava. Ore accounts dating from 1541 provide the earliest record of mining on Bonsall Moor but most of the surviving surface remains represent mining activity of the 18th and 19th centuries. In 1881 Slack Mine and the adjacent mines were bought by Edward Wass who in the following year had his agent, Jonathon Stevenson, examine the New Shaft at the mine. This examination revealed water at a depth of 222 feet (67.6m). As a result it was proposed to extend the 18th century Dalefield sough (a level driven primarily for drainage), over a distance of 800 yards (732m) to the mine. Although this was started, the task was never completed due to financial constraints. The mines would have been worked under the jurisdiction of the Barmote Courts, the legal administrative unit governing Derbyshire lead mining. The Derbyshire system of mining was largely based on local mining customs and consisted of individual groups of miners or small mining companies working relatively short lengths of the vein. The monument survives as a series of earthwork, buried, standing and rock cut remains which include several almost parallel veins and scrins. These are aligned roughly north to south and are marked by a series of hillocks (mounds of waste rock which either contain insufficient quantities of ore to warrant extraction, or waste from ore crushing activity) interspersed with the remains of mining shafts and open cuts (veins worked open to daylight). Slack Mine, which includes Nether Slack, Upper Slack and Scorah Slack, is situated on two parallel veins. At the northern end of the monument, in the area of Nether Slack, is a shaft which was documented in the late 18th century as being 50 fathoms deep. This has now partly collapsed but sits adjacent to a retaining wall and a coe, close to Bonsall Lane. Close to these remains is an ore processing area including a water channel and a buddling area where water was used to separate small sized ore from adhering dirt. Towards the southern end of the monument, in the vicinity of Scorah Slack, is a large shaft surrounded by a substantial coe with retaining walls. Similar remains characterise Mount Pleasant and Barmasters Grove mines which are situated in the eastern half of the protected area. Within the easternmost field are the remains of at least ten open shafts scattered along the lines of hillocks, hollows and deep open pit holes which mark the line of the lead veins. The individual mines are not marked by concentrated areas of activity but instead relate to stretches of the vein which were worked by different miners or groups of miners, a characteristic of the Derbyshire lead mining custom. All modern fences, gates and stiles are excluded from the scheduling although the ground beneath them is included. SELECTED SOURCES Book Reference - Author: Rieuwerts, J. - Title: The Lead Mines of Bonsall Moor - Date: 1997 - Type: DESC TEXT - Description: Report held in Peak Park Office