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Summary

A complex of leats extends for 2 kilometres from the upper part of Blackbrook River and its tributaries to the lower course where the leats seem associated with the local tin streamworks.

Location

Protected Status: none recorded

Other References/Statuses

• National Monuments Record: SX67SW100
• National Record of the Historic Environment: 910057
• Old DCC SMR Ref: SX67SW/108
• Old DCC SMR Ref: SX67SW/173
• Old DCC SMR Ref: SX67SW/174

Monument Type(s) and Dates

• LEAT (Post Medieval to Early 20th Century - 1540 AD (Between) to 1901 AD (Between))

Full description

Royal Air Force, 1946, RAF/CPE/UK/1890, 1301 (Aerial Photograph). SDV169268.

Greeves, T. A. P., 1982, Dunnabridge Farm (Plan - measured). SDV266230.

(11/05/1982) DNP survey drawing shows 'leat?' taking sinuous course from Roundhill Farm at SX 6066 7419 to Blackbrook River at SX 6162 7414.

Royal Commission on the Historical Monuments of England, 1985, Aerial Photograph Project (Dartmoor) - Dartmoor Pre-NMP (Cartographic). SDV319854.

Leat visible extending from SX 60167400 to SX 60637415. This leat is approximately parallel to another leat which runs alongside a little to the south:
This leat is visible between SX 60657314 and SX 60007396 where it leaves the map. It may be associated with another leat, crf: SX67SW/108. A ditch runs into this leat at SX 60127396 (visible on 1946 aerial photograph).

Royal Commission on the Historical Monuments of England, 1985, Aerial Photograph Project (Dartmoor) - Dartmoor Pre-NMP (Cartographic). SDV319854.

Parts of this feature are shown as a wall on Ordnance Survey 6" 1954 map. This leat appears to be two leats, the first of which runs into the second:- 1. Sx60667419 to sx61167409.2. Sx60987399 to sx61627414. However, the leat is probably continuous (i.e. one continuous feature) and the section between sx60987398 and sx61177408 has probably been confused with what looks like a modern drain shown in the Dartmoor National Park survey 1982. The leat has been drawn as two features, as it appears on the RAF 1946 photo.

Royal Commission for the Historical Monuments of England, 1987-1993, Duchy Farms Project Survey Visit (Report - Survey). SDV350839.

(22/04/1988) A complex of leats extends for 2kms from the upper part of Blackbrook River and its tributaries to the lower course where the leats seem associated with the local tin streamworks.
They start on Tor Royal Farm as two fairly parallel leats. One, at SX 60157400, is sourced from a tributary of the Blackbrook, the other from the stream itself, 450m further W.
Where they enter the fields of Roundhill Farm they are 20m apart with a 4m difference in contour height but converge to a distance of 10m and a height difference of 2m at SX 67647421, immediately S of Roundhill house and gardens, which have apparently destroyed the courses of both leats.
In a field 90m N of the farm buildings a single leat emerges to make a broad northern loop before turning to the SE. (Initially it comes within 50m of the Wheal Harmony openworks of 1832 (SX 67 SW 322) but no clear evidence of a branch leat could be found).
At SX 61187409, on its SE extension, the leat combines with another, 650m long, sourced by the Blackbrook some 230m to the W. This continues eastwards and, via a series of extensive streamworkings, re-joins the Blackbrook at SX 61627415.
Generally the leat channels, all dry, are rather less than 1m wide and 0.2m deep and barely traceable across peat cutting areas in the northern loop. Upcast banking is usually faint, but from SX 60877424 south-eastwards to the lower leat its form changes dramatically. The channel is 1.2m wide and 0.2m deep but accompanied by a bank on the lower SW side that is between 2.5m and 3m wide and from 0.6m to 1m high. Perhaps the course necessitated an originally greater cutting: there is no obvious quarrying for material. A slight ditch on the lower side of the bank could never have produced the volume. Although there are a number of breaks in the bank to be effective it would originally have had to be continuous.
It is impossible to date these streamworking leats but reasonable to assume that the initial pair were disused when overlaid by Roundhill farm buildings which, from the Tithe Map, were being established by 1839.

Environment Agency WMS, 2020, Environment Agency LIDAR Composite DTM 2020 - 1m (Cartographic). SDV364513.

Sources / Further Reading

Associated Monuments

Associated Finds: none recorded

Associated Events

• EDV8627 - Roundhill Farm Duchy Farms Survey
• EDV8628 - Tor Royal Farm Duchy Farms Survey
• EDV8409 - Dartmoor Royal Forest Project

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