A collection of walks, discoveries, insights and pictures of exploring Dartmoor National Park
June 15, 2025
Upper Merrivale Tinners’ Mill(s)
On the latest OS Map (1:25k), centred at SX55196 76639 and on the right hand (west) bank of the River Walkham is a feature described as ‘Blowing House (remains of)’. In the 1990’s, the Dartmoor Tinworking Research Group (DTRG) conducted a thorough excavation of the site over five seasons, establishing that the site had actually been used and modified through 5 different phases over a 200 year period in the 16th and 17th Centuries. The DTRG had originally planned four seasons of work at the Upper Merrivale Mill(s), with the fourth season being in 1994, which was the 500th anniversary year of the Great Court held at Crockerntor on I1th September 1494.
During their excavations, the DTRG also found evidence for (probable) medieval tin streaming and the later processing of ore. They confirmed there were two Mill structures here (known as Mill A and Mill B), where both stamping (crushing) and smelting took place plus there were Dressing Floors nearby.
The DTRG excavations revealed that during a 3rd phase of the site, sometime in the 16th century, Mill (B) and its associated wheelpit were constructed. Then, in the early 17th century (between 1600-1650), a stamping mill, known as Mill (A) was constructed before it was replaced by a Blowing Mill on the same footprint later in that century. The building of the late 17th century Blowing Mill was conducted in what the DTRG describe as being the 5th phase. This later mill survives with a well defined wheelpit and a very large mould stone within its walls. Research has shown that the years 1691 – 1714 were relatively prosperous for the Devon tin industry with the production peak peak being around 1706. 24 years later, in 1730 only two blowing mills were still operating in Devon, namely; in Sheepstor and in Plympton, therefore a reasonable assumption is that the Upper Merrivale Blowing Mill had ceased work by then
One key question to be asked about the location of this (and the other two Walkham Tinners’ Mills) is where did the ore come from? The possibilities include but are not limited to; Dead Lake, large excavation around the head of a minor stream below Greena Ball, Roos Tor Pits and Beckamoor Combe.
Downstream from both Mills, once scattered mortar, mould and axle (bearing) stones have been grouped together. During a recent (June 2025) walk with the DTRG, the author and members of the society conducted some (light) vegetation clearance in the area of these scattered stones, making them more visible to visitors of this site.
Bibliography
Dartmoor Tinworking Research Group (DTRG) – Newsletters Nos 1-4 (July 1991, January 1992, July 1992, January 1993)
Worth’s Dartmoor (1967 – First Impression) – The Blowing House (pages 309/10)
Jeremy Butler (1991) – Dartmoor Atlas of Antiquities (The North) – Map 30 – pages 79 and 80
Sketch map of the Upper Merrivale Tinners’ Mills based on a 1996 plan of the excavations created by DTRG
The 5 phases of history associated with the site have been recorded by Dr Tom Greeves thus: 1) during medieval or earlier period the area was streamed for alluvial tin; 2) Medieval (?) processing of tin ore; 3) Eastern wheelpit serving a mill (Mill B); 4) Stamping mill constructed within the present visible structure and 5) Visible building (blowing mill), furnace, post-hole evidence for timber supports for bellows, stone bench, mouldstone, stonelined buddle and occupation surfaces – to circa 1700.
This simplified sketch map is a slightly modified version of one in Jeremy Butler’s Dartmoor Atlas of Antiquities (The North)Overlooking Mill A of the site, with its distinctive mould stone overlooking River Walkham and Great Mis Tor beyondMill A with the adjacent wheelpit. This mill was once a stamping mill (phase 4) before being converted into a blowing mill (phase 5). An interesting scenario considered by Mike Dickinson, former Devon Record Office archivist, with phase 4 is that it was precipitately abandoned on the call to arms for the civil war in 1642. Mike Dickinson states this idea is “unconvincing”Another view of Mill A, which is oriented north-west to south-east. Intriguingly, Worth records (Worth’s Dartmoor – Page 309) that this is a blowing house, which is less well preserved that the two preceding examples (ie those on the left (east) bank of the Walkham) and is not rectangular. Worth measurements were 38ft 9in (12m) and 33ft (10m) for the two long sides and 14ft (4.27m) and 12ft 6in (3.8m) for the ends. The DTRG recorded in 1991 that the “sides were masked by a steep turfed slope, but evidence for their position suggests a building measuring approximately 11 metres by 4 metres”. Wheelpit associated with Mill A. The wheelpit was cleared and excavated by the DTRG in 1991. It had been backfilled with rubble and contained early 17th century tobacco pipes!The wheelpit measures according to Worth 8ft 6in (2.6m) x 1ft 6in (0.46m)The walling of Mill A, when it was a Blowing House is from the 5th phase of the site, dating from late 17th century. The DTRG established that there had been a stamping mill here prior to this period (early 17th century) although not much of the original walling remains.The mould stone in Mill A. It has a small ‘sample’ ingot in the bottom left corner (as viewed in the photograph)Worth (pages 309/10) records that “no complete Mould Stone had been found at this site, but there is a broken mould, 8 in wide at the top, length not ascertainable, depth not less than 3 in”. Worth’s observation is rather confusing given the obvious (current) location of the above Mould Stone example. Worth recorded his findings circa 1929, so one wonders how this prominent stone was missed. The author has found a sketch by Dr Tom Greeves, which is dated 1976 and shows this mould stone in situ then, so how did Worth miss it ?The mould stone is probably in situ from where it was last usedThis is a sketch made by Worth on 27th August 1929 of Mill A. Clearly, there is no mould stone recorded. Worth appears to have completely missed it (maybe it wasn’t visible). How did it become visible between 1929 and 1976 (date of Dr Tom Greeves sketch)?Just outside Mill A, towards the river there is a mortar stone, testament to period of Stamping (crushing) which took place hereContextual picture of the mortar stone in relation to the riverMill B. In the Summary Report on the 2nd season of excavation at Upper Merrivale Tin Blowing and Stamping Mill by DTRG in 1992, it has been recorded: “When the furnace was operating in Mill A, stamping was being carried out in Mill B. (The) Stamping mill was probably crushing tin slag as well as ore”. The overall dimensions of Mill B are 7.4m north-south and 2.8m – 3.5m east-west. At the south end of the structure is a recess, internally measuring approximately 1.5m by 1.3m.Mill B was served by leats and there is a leat embankment aligned with the wheelpit (shown in picture above).Close up of the Wheelpit associated with Mill B. A dump of slag / ore at the top of the slope this suggests that stamps were housed in Mill B driven by this waterwheelA very short distance downstream from both Mills, are a number of scattered mortar, mould and axle (bearing) stones now grouped together. DTRG members (June 2025) clearing vegetation around the scattered mortar, mould and axle (bearing) stonesThe vegetation cleared stones. There are nine rather fabulous pen and ink drawings of many of the mould and mortar stones found at the mills and here, which were drawn by Ivor West and published on the 2nd DTRG Newsletter, dated January 1992This split mould stone two constituent parts were found in different locations by DTRG during their excavations of the site. One part was found in the riverClose up of a mould stoneClose up of various mortar stonesGreat Mis Tor from the southern end of Mill B
