Summary
Multi period lead rakes, a nucleated mine with ore works, smelt mill and enclosure 440m north of Charterhouse Warren Farm.
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. Lead rakes are linear mining features along the outcrop of a lead vein resulting from the extraction of relatively shallow ore. They can be broadly divided between: rakes consisting of continuous rock-cut clefts; rakes consisting of lines of interconnecting or closely-spaced shafts with associated spoil tips and other features; and rakes whose surface features were predominantly produced by reprocessing of earlier waste tips (normally in the 19th century). In addition, some sites contain associated features such as coes (miners' huts), gin circles (the circular track used by a horse operating 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 16th-18th century date, but earlier examples are likely to exist, and mining by rock-cut cleft has again become common in the 20th century. 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. Nucleated lead mines are a prominent type of field monument produced by lead mining. They consist of a range of features grouped around the adits and/or shafts of a mine. The simplest examples contain merely a shaft or adit with associated spoil tip, but more complex and (in general) later examples may include remains of engine houses for pumping and/or winding from shafts, housing, lodging shops and offices, powder houses for storing gunpowder, power transmission features such as wheel pits, dams and leats. The majority of nucleated lead mines also included ore works, where the mixture of ore and waste rock extracted from the ground was 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 sizes (either by manual hammering or 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 vary widely and 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. The majority of nucleated lead mines with ore works are of 18th to 20th century date, earlier mining being normally by rake or hush and including scattered ore dressing features. Nucleated lead mines often illustrate the great advances in industrial technology associated with the period known as the Industrial Revolution and, sometimes, also inform an understanding of the great changes in social conditions which accompanied it. Because of the greatly increased scale of working associated with nucleated mining such features can be a major component of many upland landscapes. It is estimated that several thousand sites exist, the majority being small mines of limited importance, although the important early remains of many larger mines have often been greatly modified or destroyed by continued working or by modern reworking. Ore hearth smelt mills were introduced in the 16th century and continued to develop until the late 19th century. They were the normal type of lead smelter until the 18th century, when they were partially replaced by the reverberatory smelt mill. The ore hearth itself consisted of a low open hearth, in which lead ore was mixed with fuel (initially dried wood, later a mixture of peat and coal). An air blast was supplied by bellows, normally operated by a waterwheel; more sophisticated arrangements were used at some 19th century sites. The slag from the ore hearth still contained some lead. This was extracted by re-smelting the slag at a higher temperature using charcoal or (later) coke fuel, normally in a separate slag hearth. This was typically within the ore hearth smelt mill, though separate slag mills are known. Early sites were typically small and simple buildings with one or two hearths, whereas late 18th and 19th century smelt mills were often large complexes containing several ore and slag hearths, roasting furnaces for preparing the ore, refining furnaces for extracting silver from the lead by a process known as cupellation, and reducing furnaces for recovering lead from the residue or litharge produced by cupellation, together with sometimes complex systems of flues, condensers and chimneys for recovering lead from the fumes given off by the various hearths and furnaces. The ore hearth smelt mill site will also contain fuel stores and other ancillary buildings. Ore hearth smelt mills have existed in and near all the lead mining fields of England. It is believed that several hundred examples existed nationally. The multi period lead rakes, a nucleated mine with ore works, smelt mill and enclosure 440m north of Charterhouse Warren Farm are the finest example in the Mendip Hills mining region and will contain archaeological, environmental and chemical evidence relating to the development of lead mining, processing and settlement and its social and economic impact over a prolonged period.
History
See Details.
Details
This record was the subject of a minor enhancement on 3 September 2015. This record has been generated from an "old county number" (OCN) scheduling record. These are monuments that were not reviewed under the Monuments Protection Programme and are some of our oldest designation records.
This monument, which falls into three areas, includes multi period lead rakes, a nucleated mine with ore works, smelt mill and enclosure situated within a steep sided dry valley called Velvet Bottom. The lead rakes, mining and lead processing plants date from the Roman period although the majority of visible remains are from the early post medieval to 19th century and survive as a complex series of earthworks visible both on the ground and on aerial photographs and lidar. These areas are characterised by long linear pits or rakes measuring at least 1270m long by 1160m wide which followed the seams of lead with linear pits or lines of small pits. The smaller pits are from approximately 2m square up to 16m by 9m and the linear pits are from 27m by 4m up to 195m by 13m. At least five ore processing sites are associated with the mining activity. These contain at least 30 buddle pits which generally survive as roughly circular depressions of 8m or 11m in diameter. Excavations of one pit in 1985 showed it to have been surrounded with a wall of up to 0.6m high and had an unusual wooden floor. The buddles were used to wash the ore. One area has distinct catch pits for reprocessing silt following initial washing. Other specific structures and buildings include wheel pits, tailings dams and drains, leats, waterwheel pits, houses and offices, shafts and a possible late 17th century reverberatory smelt mill with three furnaces, condenser flues and a bed for a rare steam powered engine.
Although the initial early mining had declined from the early post medieval period, a small brick smelter was constructed in around 1824 to rework earlier slimes and slag. In 1844 the Mendip Hills Mining Company commenced production and sunk shafts up until 1847 in the Ubley Rakes area. In 1856-8 two more were sunk in Charterhouse Rakes. None of the shafts were particularly productive so work concentrated on reprocessing earlier waste materials. In around 1861 the works was sold to the Cornish smelting firm of Treffry and Co and they continued lead smelting until 1878 and dressing and buddling until 1885. Other partial excavations revealed that both a Roman and medieval lead extraction industry had been in existence before the later visible workings. A further feature associated with this earlier phase was a rectangular enclosure of approximately 50m long by 45m wide defined by an outer bank of up to 4m wide and a 4m wide ditch and an inner bank of 3m wide. In the western corner is a second smaller enclosure.
