Details

The monument includes the core part of Keaglesborough Mine together with
an historic farmstead known as Riddipit situated on the lower western
slopes of Raddick Hill overlooking the River Meavy. Keaglesborough Mine is
believed to have been operational from the early part of the 16th century
and many of the surface workings may date from this time. During the
latter part of the 18th and early years of 19th centuries tin processing
facilities, including two stamping mills and associated dressing floors,
were established. Water to power the mills and dress the tin was brought
to the site by leat from the River Meavy below Hart Tor.

The earliest industrial remains within the monument are a series of
parallel dumps surviving at two places on the edge of an openwork. These
represent the much truncated remains of an earlier eluvial streamwork
which was largely removed during subsequent opencast mining operations,
resulting in the formation of the substantial openwork which is up to 10m
deep. Subsequent mining was carried out underground with the only evidence
at the surface being an adit cut into the base of the openwork and two
shafts further to the east. Much of the tin from the underground workings
would have been crushed and dressed in the stamping mills and dressing
floors. Both mills survive as rectangular platforms denoted on three sides
by drystone wall revetment. In the centre of each platform is a
stone-lined pit in which the wheel providing power for the stamps rotated.
Leading from each wheelpit is a well-preserved channel known as a
tail-race, which would have carried water from the wheel. On the northern
side of these wheelpits and tail-races are a series of rectangular and
triangular hollows which represent the site of buddles and other devices
used to separate the cassiterite (tin dioxide) from waste materials.
Collectively these structures form the dressing floor. Irregular shaped
mounds standing in the vicinity of the dressing floors represent waste
material discarded during the dressing process. The water supply to each
mill was carried to the wheel on a leat embankment and timber launder. The
eastern leat embankment, in particular, survives as a revetted bank
standing up to 1.9m high, whilst both timber launders will survive only as
buried features.

A short distance to the west of the northern end of the eastern dressing
floor is a rectangular earthwork which may represent the site of a small
building connected in some way with the mine.

Riddipit farmstead stands at the lower end of the openwork and survives as
a group of two long buildings, together with ancillary structures,
situated around a central courtyard. The farm at Riddipit certainly dates
to the middle part of the 16th century, but may have earlier origins.
Considerable quantities of 16th and 17th century pottery recovered from
the site provide evidence of occupation during this period. All of the
surviving buildings are of drystone construction with the walls standing
up to 1.6m high. The farmstead was abandoned in the middle part of the
19th century.

All modern fence posts within the monument 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.

Source: Historic England

Reasons for Scheduling

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.

Despite afforestation, Keaglesborough Mine and Riddipit farmstead survive
well and together provide a glimpse into the often complex relationship
between historic mining and farming. The earthworks and structures
associated with Keaglesborough provide an insight into the development of
tin extraction, but of special importance are the well-preserved stamping
mills, which will contain information relating to the technological
character and efficiency of tin extraction.

Source: Historic England

Sources

Other
Devon County Sites and Monuments Register, SX57SE157.01, (1989)
Haynes, R.G., Ruined Sites on Dartmoor - Middleworth, 1966, Unpublished Manuscript
MPP fieldwork by S. Gerrard, Gerrard, S., (2002)
MPP fieldwork by S. Gerrard, Gerrard, S., (2002)

Source: Historic England