Scheduled Monument: HOW GROVE LEAD MINE (1402079)

SUMMARY OF MONUMENT How Grove is a small lead mine of mid-C18 to the early C20. It is situated on an island of preserved hillocks on Dirtlow Rake, Derbyshire. REASONS FOR DESIGNATION Rarity: It is a rare survival of an exceptionally late lead mine with well preserved remains of individually rare features such as circular buddles which were more common in south-west England, north Pennines and Wales and D shaped buddles which may be unique to the area. Survival: It is an exceptionally well preserved site displaying a diversity of surviving features, which are more often than not destroyed during later phases of mining activity. Documentary Evidence: A relatively detailed and almost continuous picture of mining on Dirtlow Rake is available from the surviving Castleton Barmaster Books, Group Value (association): How Grove sits within an area of well preserved mining remains the best surviving of which are designated as Scheduled Monuments. Combined these sites provide evidence for both the historical and technological development of what was once a far more extensive, multi-period and regionally distinct mining landscape. HISTORY Approximately 10,000 lead industry sites are estimated to survive in England, spanning nearly three millennia of mining history from the later Bronze Age (c1000 BC) until the present day, although before the Roman period it is likely to have been on a small scale. Lead rakes are linear mining features along the outcrop of a lead vein resulting from the extraction of relatively shallow ore. Some sites contain associated features such as coes (miners' huts), gin circles (the circular track used by a horse driving simple winding or pumping machinery), and small-scale ore-dressing areas and structures, often marked by tips of dressing waste. The majority of rake workings are believed to be of C16 - C18 date, but earlier examples are likely to exist. Rakes are the main field monuments produced by the earlier and technologically simpler phases of lead mining. They are very common in Derbyshire, where they illustrate the character of mining dominated by regionally distinctive Mining Laws, and moderately common in the Pennine and Mendip ore fields; they are rare in other lead mining areas. How Grove lead mine is situated approximately 1km south of Castleton, on a small island of preserved hillocks on Dirtlow Rake, and dates from the mid-C18 to the early C20. Dirtlow Rake is one of several, roughly parallel, veins in this part of the ore field that have been extensively mined, originally for galena with discarded gangue minerals of fluorspar, calcite and barytes. Much of the rake was heavily re-worked for gangue material (minerals which accompany metallic ores) in the late C20. The earliest mention of Dirtlow Rake is as a place name in 1538, but the earliest known direct documentary reference to mining the vein is in 1672. In the open cuts of Dirtlow Rake between How Grove and Pin Dale, there is evidence of pick work on the sides of the veins which is undoubtedly of pre-C18 date, executed before gun powder was in common use, and may well be much earlier. The earliest workings were surface opencasts, but it is unclear how deep the mines may have become by C17 when soughs and pumping engines started to be employed across the ore field. Until this time the depth of working was determined by the water table, which was relatively shallow in the eastern half of the ore field, rarely exceeding 50-75m. At Dirtlow Rake the water table greatly exceeded this, and given the vertical nature of the ore beds, early mining may have been restricted by the sensible limit to which ore could be brought to the surface with stowes (winding gear) rather than engines. In the C17 and C18 engine shafts were sunk into a series of mines along Dirtlow Rake, which are known to have had adjacent gin engines used for winding ore from below. A relatively detailed and almost continuous picture of mining on Dirtlow Rake is available from the surviving Castleton Barmaster Books, which date from 1752. It is documented that How Grove was named after a local mining family and was worked by a series of partners, each with a percentage of shares. A combination of ownership information and records of productivity provide a very detailed account of the mine, and demonstrate changes in the character and scale of mining through time. How Grove was worked almost continually from 1752 to 1886 with a few short intervals of apparent inactivity. By the C20 lead extraction had ceased on Dirtlow Rake, although fluorspar may have been removed in small quantities. Until the 1960s however, much remained that dated to the lead mining era, and the hillocks around How Grove were substantially intact. In the 1960s and 1970s small areas were reworked, with the fluorspar-rich parts largely being removed. More recently a large chemicals company has worked large and deep opencasts to the west of the surviving remains, which has resulted in much of the earlier evidence being removed. DETAILS The surviving area of How Grove lead mine measures approximately 126m long and up to 40m wide, and is enclosed on the northern and eastern edges by a ruinous, and partly buried, belland yard wall. To the south the edge of the scheduling is defined by a field track. The site comprises standing, buried and earthwork remains, which include a coe or miner's hut, dressing floors, a crushing circle, and ore dressing pits and channels, including a circular buddle and a water storage dam. A deep hollow near the coe may also be a run-in shaft. Much of the area was archaeologically excavated and conserved between 1998 and 2000, and many features remain exposed. The rake runs roughly south-west to north-east, and is best described starting at the south western end. Here, the first most visible feature is a coe, a rectangular structure measuring approximately 4.5m by 2.9m internally, with a doorway in the south-east corner. It is built of mortared random limestone, with remnants of internal rendering, and is set within a high hillock on the north and west sides. The west wall stands to almost full height at circa 2m, but the east wall had collapsed to circa 0.6m and has been partly rebuilt. The southern wall has also undergone some conservation to provide long term stabilisation. In the north wall is a small fireplace, and a small iron grate was found amongst the collapse material. The coe is shown on the township map of 1819, but given the floor stratigraphy it is clear it continued in use into the late C19 and early C20. Moving eastwards, there is a flat-topped dressing floor, which has been created by levelling waste heaps of tailings derived from previous ore dressing operations. Its centre is largely covered by a crushing circle and its surrounding horse track. The latter is directly linked to a narrow gateway through the northern belland yard wall by a carefully-made path with a stone retaining wall to one side, providing access for the horse from the fields to the site. The crushing bed comprises a ring of 23 large limestone slabs with an outer diameter of c4.8m and a circular timber post c0.27m in diameter at the centre. To the south west of the crusher there is a series of channels and pits, together with a possible hard-standing and the top end of the water storage pond. To the east of the crusher, built into the relatively steep side of the hillock, is a complex series of features associated with buddling, a process used for separating small sized ore from dirt by means of flowing water. The most prominent feature is a circular buddle. This measures c2.75m across, and its sides are constructed of a carefully constructed dry stone retaining wall of 4-6 limestone courses. At the centre is the stump of a circular post which probably supported a feeder launder. Approximately 0.7m east of the circular buddle is a D-shaped pit that measures 1.8m by 1.8m and is 0.5m deep. This is also interpreted as a buddle. Both the circular and D-shaped buddles were fed by launders set on a narrow horizontal terrace and supported on a dry stone wall on the down slope side. The earthen dam, for a large water storage pond, now filled with a modern hillock, survives just beyond modern disturbance. This is flat-topped, about 7m long, and built of a mixture of clay, tailings and small pieces of limestone and calcite. The 1899 Ordnance Survey map shows a pond at How Grove, the north eastern end of which matches the position of the dam. The only visible shaft in this part of the rake is 95m to the north east of the coe. The excavated structures at How Grove represent two main phases of activity. The first, of probably late C18 to mid-C19 date, has features typical of a medium sized Peak District mine, with a surviving, well-built, coe, horse drawn crusher, small dressing floor and water storage pond (later modified). The second, of late-C19 or early-C20 date, is a semi-mechanised plant, set up when the lead industry elsewhere had virtually collapsed. SELECTED SOURCES Article Reference - Author: Barnatt, J - Title: Excavation and Conservation at How Grove, Dirtlow Rake, Castleton, Derbyshire - Date: 2002 - Journal Title: Mining History Book Reference - Author: Ford, T. D. and Rieuwerts, J. H (eds) - Title: Lead Mining in the Peak District - Date: 2000 Book Reference - Author: Barnatt, J and Smith, K - Title: The Peak District - Date: 2004 Unpublished Title Reference - Author: Cranstone, D - Title: MPP The Lead Industry Step 1 Report - Date: 1992 Book Reference - Author: Barnatt, J. and Penny, R. - Title: The Lead Legacy. The prospects for the Peak District's Mining Heritage. - Date: 2004