Reasons for Designation
Tin has been exploited on Dartmoor since the prehistoric period and surviving
remains are numerous, well-preserved and diverse, with the two main types of
tinwork being streamworks and mines. The three different forms of tinwork used
to mine lode tin were lode-back pits, openworks and shafts. Lode-back pits
survive as shallow shafts which were sunk onto the lode outcrop to extract
cassiterite. These pits generally occur in linear groups following the line of
the lode, with associated spoil dumps. Many tin lodes have been worked at the
surface by digging pits onto the backs or surface exposures of the lode to
remove the mineral that lay above the water table. Openworks are also known as
beams and they were formed by opencast quarrying along the length of the lode.
The term openwork refers to the field evidence for opencast quarrying of the
lode, which produced relatively narrow and elongated gulleys.
Shaft mining is synonymous with underground extraction, with access to the
lode being through near vertical or horizontal tunnels known as shafts and
adits. Underground workings are often complex in character, with considerable
layout variations reflecting developing extraction techniques. Within the
vicinity of most mines are found the remains of prospecting activity. This
generally takes the form of small pits and gulleys. Some mines have associated
surface buildings which provided a variety of services for the working miners.
The ore quarried from all three forms of mine was taken for processing to
nearby stamping mills.
A national survey of the tin industry in England was completed in 1999. This
demonstrated the number and diversity of surviving remains and the
significance of some areas for understanding the origins and development of
the industry. Dartmoor is one such area and here a representative selection of
sites with significant surviving remains has been identified as nationally
important.
Wheal Katherine, 250m WSW of Plym Ford, forming an outlying part of
Eylesbarrow Tin Mine contains a broad range of different forms of evidence
relating to prospecting, exploitation and processing of both tin deposits
and lodes. In particular, a well-preserved stamping mill complete with
extensive dressing floor survives in close proximity to an informative
group of openworks, lode back pits and shafts.
Details
The monument includes structures and earthworks associated with Wheal
Katherine situated on the lower south facing slopes of Eylesbarrow
overlooking the River Plym. Tin extraction within the area later to become
known as Wheal Katherine probably dates back to at least the 12th century,
although it is not until the 16th century that specific documentation is
known. Some of the earthworks visible within the monument will certainly
be the result of mining activity before the better documented phases of
the 19th century. Wheal Katherine was worked both independently and at
times as part of its bigger neighbour, Eylesbarrow Tin Mine. In 1817,
three years after work commenced at Eylesbarrow, Wheal Katherine opened,
but by the 1830s it formed part of Dartmoor Consolidated Mines, whose
major concerns were at Eylesbarrow. Over the following years the mine was
managed by various companies before closing finally in 1856.
A number of different types of earthworks and structures relating to tin
extraction and processing survive within the monument. Amongst the
earliest are two areas of streamworking, both of which have been truncated
by later mining activity. The streamworks were formed during the
extraction of tin deposits using water to separate the heavy tin from the
lighter silts, sands and gravels. Once the streamworks were abandoned, the
tinners turned their attentions to the lode tin within the area. The first
stage was extensive prospecting using both pits and trenches. Large
numbers of these features survive within the vicinity of the tin work. The
pits were excavated solely by hand but the trenches were formed by using
both shovels and running water. The water was brought to the area in leats
and stored in reservoirs. Once the lodes had been identified they were
extracted using different mining techniques. Foremost among these was the
use of opencast quarries known as openworks to extract the lode tin and
these survive as deep, steep sided gullys trending approximately east to
west. The second form of evidence relating to mining survives as series of
deep pits and these are known as areas of lode back tin working. This form
of exploitation consists of deep pits being cut onto the back of the lode
with the tin ore encountered being raised to the surface. When extraction
became difficult the pit was abandoned and a new one opened elsewhere on
the lode. The resulting archaeological remains include linear series of
deep pits each associated with a spoil dump. The final form of mining is
represented by five particularly large pits called shafts and an adit.
These would have been dug to reach the tin ore below the depth accessible
by openworks and lode back pits. These features probably belong to the
19th century extraction phase. Ore extracted from these shafts and adits
would have been processed in the stamping mill and associated dressing
floors. The stamping machinery would have sat next to the large stone
faced wheelpit and the dressing floor survives as a series of linear and
rectangular hollows in the area south of the stamps. Two reck houses in
which the tin was further refined survive towards the southern edge of the
dressing floor. The final product from this processing area would have
been black tin which would have then been transported elsewhere for
smelting.
Amongst other structures surviving at Wheal Katherine is a wheelpit at
SX61036849 which would have provided power for pumping and perhaps lifting
at the nearby shaft, a stone revetted platform at SX60936845 and a
semicircular earthwork at SX60696836 both with no obvious function, two
tinners' buildings which would have provided shelter or storage, a small
building associated with two small fields and several leats.
MAP EXTRACT
The site of the monument is shown on the attached map extract.
It includes a 2 metre boundary around the archaeological features,
considered to be essential for the monument's support and preservation.
