Reasons for Designation
For several millennia the south west peninsula has been one of the major
areas of non-ferrous metal mining in England, its more important and
prolific products including copper and tin along with a range of minor
metals and other materials, notably arsenic, which occur in the same ore
bodies. Before the 16th century, exploitation of this region's non-ferrous
metal resources almost exclusively involved tin. Extraction was focussed
along valley floors and hillslopes on and around the granite uplands of
the south west where tin ore had accumulated after natural erosion from
the parent lodes. These accumulations were exploited by streamworks, using
carefully controlled flows of water to expose and then concentrate the
ore, leaving behind distinctively deepened valley floors with various
patterns of spoil heaps.
By the early post-medieval period, most substantial deposits susceptible
to streamworking had become exhausted and exploitation increasingly
transferred to the mineralised lodes themselves; a change which also marks
the appearance of copper as an important product of the south western
mining industry. The early post-medieval exploitation of lodes was
restricted by the ability to drain the cut, resulting in relatively
shallow workings directly into the lode exposures at the bedrock surface,
often by pits called lode-back pits and sometimes enlarged to form longer
openworks along the lodes.
By the 18th century, ore extraction and processing rapidly expanded to
meet growing demands, aided and promoted by technological development.
Surface workings became larger and more extensive, and deeper extraction
was achieved from shafts, the water pumped from larger mines by early
steam engines or drained through near-horizontal tunnels called adits
which also served to access the lodes. Horse powered winding engines
lifted the ore from the shafts while larger and more efficient water
wheels served ore-processing areas. By such means, west Cornwall became
England's main producer of copper in the 18th-early 19th century.
Intensification accelerated in the late 18th-early 19th century with more
efficient steam-powered pumping engines allowing deeper shafts from which
extensive underground workings spread out. By the mid-19th century, steam
also powered winding and ore-processing operations, the engines, boilers
and ancillary machinery housed in distinctive masonry buildings grouped
around the main shafts and dressing areas. Later in the century,
compressed air was used for underground extraction equipment, fed from
steam-powered compressors on the surface. Ore-processing became
increasingly mechanised, along with the development of more effective
methods of separating and retaining different ores, notably in the
production of arsenic which became a major saleable product in the 19th
century. With these advances, east Cornwall and west Devon supplemented
their tin production to become one of the world's main sources of copper
and arsenic ore until the later 19th century, while in west Cornwall,
copper ores became exhausted and replaced as that areas main product by
the tin ores present at deeper levels.
From the 1860s, the south western mining industries began to decline as a
result of competition from cheaper sources of copper and tin ore overseas,
especially from South America, leading to a major economic collapse and
widespread mine closures by 1890, though limited ore-extraction and spoil
reprocessing continued into the 20th century.
The extensive remains from tin and, later, copper ore extraction in this
scheduling across the northern slopes of Caradon Hill provide an excellent
and rare survival from mining spanning the medieval period to the 20th
century, accompanied by a wealth of contemporary documentation for much of
that period. Despite the inevitable modification of some earlier features
by later works and the relatively limited areas of collapse which have
affected some later built structures, this scheduling presents areas of
good coherent survival from each main developmental phase of ore
extraction in south west England, these survivals combining to give an
even greater collective value. Within this overall context, certain
specific survivals are especially rare, notably the 1880s ore processing
works at Wheal Jenkin and the features pertaining to flat-rod power
transfer at the West Rosedown Mine. Of particular significance is the
survival across the same slopes of a medieval field system sufficiently
extensive and intact to demonstrate the nature of agricultural land use in
that period and its close adaptation to the slope and altitude, but also
illustrating well the relationship between medieval mining and the
agricultural context into which it expanded.
Details
The monument includes extensive remains from medieval to 20th century tin
and copper mining and a medieval field system on the middle and lower
northern slopes of Caradon Hill on south east Bodmin Moor. This scheduling
is divided into three separate areas of protection comprising the mining
remains with the field systems and two sett boundary stones. The earliest
remains from ore extraction in the scheduling appear as a broad deepened
channel called a streamwork along the floor of Caradon Coombe, the valley
along the northern edge of Caradon Hill. Medieval in origin and named the
`Chepman Wille Worke' in 1515, the streamwork exploited tin ore weathered
from its parent lodes and accumulated in valley floor silts. Controlled
water flows flushed away the overburden of soil and grits, exposing the
heavier ore which was dug out and further concentrated. The surviving
channel, modified over much of its length by later mining, is only
included in this scheduling to the south of the modern property boundary
along the valley floor. As it extended west along Caradon Coombe, the
streamwork disrupted the lower edges of an earlier medieval field system
which enclosed most land in this scheduling. It varies in character; at
lower levels in the north east of the scheduling, the slope rising from
the valley floor is subdivided by curving strip fields with an overall
north east-south west axis, separated by low earth and rubble banks. A
bank across their lower ends was largely destroyed by the streamwork and
the strip field area itself is crossed by later mining pits and truncated
to the east by 19th century mining. The strip fields' uphill limit is
defined by a bank and ditch which also extends beyond the western limit of
the strip fields, following a WSW-ENE alignment towards the head of the
valley to form a major boundary in the differing partition of the higher
ground. Beyond sites of later mining disturbance, land on both sides of
that boundary is generally cleared of surface stone and bears faint
cultivation ridging; further low banks parallel with, and at right angles
to, the major boundary show the ridging was subdivided into large
sub-rectangular plots. The field system's elements are complementary: the
strip fields form more intensively cultivated land serving a settlement
beyond this scheduling, while the lightly ridged sub-rectangular plots on
higher ground typify a less intensively used `outfield' area with
intermittent cultivation between long stock-grazed fallow periods.
As streamworking exhausted the valley floor tin ore deposits, extraction
focussed on mineral lodes in the bedrock. Small prospecting pits were dug
to locate lodes which, when found, were dug into by larger pits, called
lode-back pits. Lode-back pits are commonly 4m-8m across, surrounded by
spoil and choked by collapse at about 1m-3m depth. Their original depth
was limited by the ability to drain them once the water table was reached;
another pit was then dug further along the lode. As a result, the numerous
lodes across these slopes, most on an overall WSW-ENE alignment, are
matched by linear scatters of lode-back pits on a similar axis across much
of this scheduling, with extensive prospecting pitting and exploitation of
local ore concentrations in intervening areas. The pits overlie all
elements in the medieval field system confirming the field system's
earlier date. Lode-back working here enters the historical record as the
`Carradon Downe Worke' in 1570; similar later references show this
activity and knowledge of the rich lodes continued into the 18th century
when major advances allowed their deeper exploitation.
By the early 19th century, the eastern third of the scheduling lay in the
Marke Valley Sett, an area of mining rights, while the rest lay in the
West Rosedown Sett, sometimes called the Wheal Jenkin Sett. At least three
well-spaced granite posts, each incised `MV' on one face, survive along
the sett boundary in this scheduling. The scheduling contains three major
foci of 19th century mining in these setts, with intensive work underway
at all three from the 1820s-1830s. In the north east is the Salisbury
Shaft complex of the Marke Valley Mine; across the centre of the
scheduling is the West Rosedown Mine, and in the west is Wheal Jenkin.
Early work in the Marke Valley Sett was in the east, beyond this
scheduling, followed by more productive operations in the west, mostly
extracting copper ore from the Engine Shaft, also beyond this scheduling,
and from 1850 at the Salisbury Shaft, within this scheduling, where a
pumping engine was installed to which a stamps or winding engine was added
in 1864. By the mid-1860s the mine produced about 5000 tons (5100 tonnes)
of copper ore annually, but its ore quality declined. In the 1870s the
Marke Valley Mine's company acquired the West Rosedown sett and in 1881
they moved their centre of operations to Wheal Jenkin, abandoning
Salisbury Shaft in 1883. Extensive remains of the Salisbury Shaft complex
include the shaft with its adjacent pumping engine house surviving to 9m
high; its boiler house is further collapsed but its chimney stands about
15m high. A stamps/winding engine house 35m south east of the shaft is
largely collapsed but remains of its loadings, sunken boiler house and
chimney survive well. Another winding engine house, 95m SSW of the shaft,
survives to gable height on the south and retains its bedstone and
loadings, with its sunken boiler house extensively intact, as is its
chimney. Other surviving remains include extensive spoil heaps on the
slope below the shaft; a large reservoir to serve a levelled
ore-processing area surviving east of the shaft, with an associated
masonry support; two small buildings near the pumping engine boiler house;
remains of an incline ascending the slope on the east of the complex
linking the processing area with the railway branch line; at least three
further shafts near the centre and southern edges of the overall complex,
and many leats and overgrown earthwork features. The West Rosedown Mine
crosses the hillslope about 0.5km south west of Salisbury Shaft. After
initial working of tin lodes already exploited by lode-back pits, a shaft
was sunk high on the midslope in the south of the scheduling, where a
pumping engine was installed in 1845. Later work focussed on a second
shaft sunk 295m downslope where another pumping engine was set up in 1858;
the higher shaft engine was removed but work there continued with pumping
powered by flat-rods from the lower shaft's engine. Always a small
operation, dwindling production led in the mine's closure in 1873.
Surviving remains include at least five near-level tunnels called adits
from the mine's earliest phase but also draining later 19th century
workings. They are spaced across the slope from high up near the
scheduling's southern edge, the northernmost extended under a valley floor
tramway embankment by a masonry tunnel with an arched portal. Both
post-1845 mine shafts are visible, each with a large spoil heap which, at
the higher shaft, supported a horse-powered winding engine. From the
flat-rod arrangement are a balance-bob pit and loadings at the higher
shaft and the trench and embankment which carried the flat-rods downslope
to the lower shaft. North of the lower shaft are remains of its engine
house and, to the east, the mine's main access track. In the angle between
that track and the shaft's spoil heaps is another horse-powered winding
engine platform. South west of the shaft are two largely intact
rectangular reservoirs with associated supply and overflow leats. At the
third 19th century mining focus, Wheal Jenkin, shafts were sunk from 1824
on a lode whose lode-back pits follow much of this scheduling's southern
edge. By the late 1830s, an engine house, dressing floors and
horse-powered winders served three main shafts, with the `Wheal Jenkin
Adit' extending 275m from the shafts to discharge beside the valley floor.
This phase contracted considerably by the 1860s and closed in 1872. When
acquired by owners of the Marke Valley Mine, one of the 1830s shafts was
re-excavated and renamed Bellingham's Shaft, pumped from 1886 from a new
engine house alongside. A stamps engine house was built to the north east,
with a substantial ore-processing works sited north of that. Despite this
scale of works, output was poor and the mine closed in 1890. Wheal Jenkin
retains good survivals, especially from the 1880s phase but including at
least two of the 1830s shafts: Whim Shaft and Pink Shaft. The Bellingham's
Shaft pumping engine house survives to gable height, with its 1886
datestone and remains of its boiler house. To the south east are two
substantial reservoirs while north of the Pink Shaft are footings of
ancillary buildings including the smithy, dry, carpenter's shop and
office. An ore tramway bed heads from Bellingham's Shaft towards extensive
remains of the stamps engine house, its boiler house and chimney. West of
that engine house is a further shaft and a large reservoir which served
the ore-processing works. That processing works is compact, containing at
least 21 round buddles, settling tanks, water wheel pits, dressing floors
and channels, matching in detail a contemporary mine plan. To its north, a
stream flows from the Wheal Jenkin Adit into the streamwork channel while
leats survive extensively across many parts of the mine. Prominent in the
later 19th century mine infrastructure was the Liskeard and Caradon
Railway whose abandoned trackbeds of 1876-7 cross and extend beyond this
scheduling following two main routes. One follows the midslope across the
West Rosedown and Wheal Jenkin Mines; the other enters the upper part of
the Marke Valley Mine to be extended by a tramway to the lower slope and
back towards the Salisbury Shaft. With economic failure of the mines it
served, the railway went into receivership in 1890.
Beside the deep shaft mining, many ore processing and spoil reprocessing
sites had been established along the valley floor streamwork by the 1830s,
some still visible in the scheduling. This activity continued throughout
the 19th century but the scheduling also includes at least two phases of
20th century reprocessing dumps beside the valley floor, from 1936 and
from the 1970s.
The following structures are Listed Buildings Grade II: at Wheal Jenkin,
the Bellingham's Shaft pumping engine house, the stamps engine house and
its boiler house chimney; at the Marke Valley Mine, the Salisbury Shaft
pumping engine and winding engine houses, their boiler house chimneys and
the upstanding chimney between them. All modern fences, gates, notices,
signs and their posts are excluded from the scheduling, although the
ground beneath them is included.
MAP EXTRACT
The site of the monument is shown on the attached map extract.
