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This walk:  2019-5-18. Adit, clam bridges, West Okement River, two wheelpits, finger dumps, reservoir sluice,  Meldon Pool, weighbridge building, kiln (west), Meldon Viaduct, woods, kiln (east), turbine house, magazine, aplite quarries, Meldon Dam & Reservoir, surveyors pillars.

Walk details below - Information about the route etc.

Previous walks in this area:  25 April 2012 21 August 2013 29 May 2015

Reconnaissance walks:  18 April 2019 30 April 2019  

Google Satellite map + GPS track of the walk 

 

 

Introduction

The Meldon area is unusual for Dartmoor in that it is located in the aureole of mixed country rock that surrounds the granite massif of Dartmoor. It has a chequered history of industrial working between medieval or post-medieval (tin working) and quarrying for limestone and aplite ended soon after 1921. Limestone was crushed and burned with charcoal to make lime that was spread on soil to "sweeten" it or less acid, and thereby more productive (coastal communities used seaweed). 

Limestone - "A rock composed almost entirely of calcium carbonate and typically formed from the accumulated remains of plankton with lime-rich structures or shells"

There is an adit near the Pool with shafts on the slopes above it, and other metal-working (tin?) remnants east of the West Okement River - they are probably Medieval. An estate map for Okehampton shows the lime kiln on the east bank of the West Okement River was there in 1790.

Parts of the site have been abandoned and then redeveloped so it is difficult to give a simple timeline. For instance, the 1841 Okehampton Tithe Map shows the original quarry with buildings around it. These were lost as the quarry expanded. Later, aplite - which contains rare minerals - was discovered in the limestone around 1889 and led to the establishment of the two aplite quarries to the east. A short-lived glass-making venture was also undertaken, although this ended around 1921.

Aplite - "Fine to medium grained acid igneous rock with a similar mineral composition to granite. Also commonly known as ‘microgranite’"

The limestone (and aplite) seem to have been worked out from a commercial standpoint. The limestone is surrounded by cherts which is "waste" in this operation and the original quarry went quite deep in the chase for limestone (as deep as the viaduct is high) and eventually the flooding and pumping probably made the undertaking unprofitable.

Chert - "Very fine-grained sedimentary deposit formed by the deposition of silica, which can be derived from plankton such as radiolaria, sponges or seepages from volcanic vents. Typically very hard, even glassy and can occur as thinly bedded deposits or as separated bands or nodules. Flint is a type of chert."

At some point, quarry waste was crushed for railway ballast and taken by tramway up an incline to the London & South West Railway, passing in front of the pre-1790 lime kiln but there seems to be no sign of this on the available maps, except that an incline was built right in front of the east lime kiln.

 

Further reading

DNPA Case Studies: (1) Geology & Geomorphology, (2) Ecology & (3) Industrial Archaeology

(1) DNPA Meldon Geology & Geomorphology

(2) DNPA Meldon Ecology

(3) DNPA Industrial Archaeology

DCC & DNPA - Meldon Aplite Quarries - notes    

DCC & DNPA Meldon Case Study - Information Sheet 3F: Glass making (glossy PDF)

Peter Keene (2007), Exploring a Dartmoor Valley: The Meldon Beneath Our Feet, Dartmoor National ParkAuthority & Devon County Council.

John W Perkins (1972), Geology Explained: Dartmoor and the Tamar Valley, David & Charles, Newton Abbot, Devon.

 

 

Car park sign. Click the image to see a larger version.

 

The walk is started via the small gate (left) beside the toilets in the car park and going through the small gate beside the field gate.

 

After leaving the car park and reaching the woods, the first thing we pass is this magnificent wall now almost completely enveloped by a row of beech trees. 

 

After descending into the wood and reaching level ground, there is a former bridge on the right with a gate between the abutments. The bank is apparently a former tramway but there is no mention of it in the usual reference sources.

 

Adit at SX 56375 92020, staining on the ground by metalliferous leaching indicates that there are metal ores in this vicinity.

 

Internal view, lit by flash.

 

Devon & Dartmoor HER - MDV120318 - Adit west of the West Okement River at Meldon Quarry
The adit is evidence of (tin) metal working; it is open for a short stretch (about 10 yards: Mike Brown (2001) Guide to Dartmoor, CD-ROM, Dartmoor Press, Grid Square 5640 9200) and was believed worked in tandem with the shafts on the slope immediately above it. Any evidence of the its spoil heap has been obliterated by later activity.  

Devon & Dartmoor HER - MDV120320 - Mine shafts west of the West Okement River at Meldon Quarry
Shafts are found above the adit similar to those belonging to the tin industry.

 

Clam bridge (i.e. a wooden footbridge) at SX 56427 920833, over the West Okement River below Meldon Dam: there is a ruinous wheelpit beside it, to the right in the photograph .....

 

Looking down at the West Okement River .....

 

Devon & Dartmoor HER - MDV20471 - Northern wheelpit at Meldon Quarry
This is one of two wheel pits found here and is the earliest; shown on the 1841 Tithe Map, it was fed by one (later two) reservoirs and a launder bank and housed a wheel of seemingly unrecorded size. . It pumped water out of the quarry by a flat-rod system and was out of use by 1905.  The wheel was of a "pitch back" design, which means that the water delivered to the top of the wheel did not overshoot it but caused it to run backwards. There is a second wheelpit just upstream ..... The flat stone near the left corner of the image has two small diameter holes .....

 

The flat stone with the two holes: the right-side one is obvious but the left-side one is near the left edge of the stone. There is a possible worn depression between the holes.

 

This photograph was taken down in the wheelpit with the river in view below - the stone has a square-section iron strut embedded in it with a large nut and washer still attached .....

 

As described above.

 

Abbout thirty-yards upstream from the clam bridge is the southern (newer) wheelpit (SX 56418 92043), built on the river bank, that housed a waterwheel about 5.5 metres (18-feet) in diameter. The walls are better preserved than the one noted above, but the structure is overgrown with trees growing inside it. Behind it is a bob-pit which housed a counter-weight that kept tension in the flatrods as they worked to operate pumps that were draining the quarry.

 

A view of Meldon Viaduct .....

 

Zoomed view.

 

 The markings indicate the position of the sluice (SX 56481 92028) below the reservoir that fed the first (older, smaller) water wheel. The wheelpit is behind, on the river bank.

 

Lesser Celandine.

 

These are waste dumps, more properly named as "finger dumps". In the late 1800s the "waste" was taken in trucks to a series of corrugated iron buildings at the northern end of the east side tramway. A transfer shed was used where the finished material was consigned to wagons operating on an incline leading to the London and South Western Rail sidings on the eastern edge of Meldon Viaduct. This incline becomes apparent as an earthwork partially obscuring the mouth of the early lime kiln. The crushed stone was used as ballast on railways and roads. Devon & Dartmoor HER - MDV120325 - Tram routes at Meldon Limestone Quarry

 

Abutments each side of the track - was this a bridge from the quarry to reach the first lime kiln or to reach the waste dumps?

 

A violet ..... Wild Sweet Violet (Viola odorata), possibly Wood Dog Violet.  Other violets: Common Dog Violet, Dame's Violet,  Early Dog Violet,  Fen Violet, Hairy Violet, Heath Dog Violet, Marsh Violet, Pale Dog Violet, Sweet Violet, Teesdale Violet, Water Violet) .....

 

Meldon Pool. Screened from the view of the stony track by a high bank and a thick canopy of trees, this scenic pool now fills the pit below the quarry face where limestone was once quarried for producing lime.  This is an old limestone quarry, now flooded. It comprises a special Carbonifereous period limestone, not found anywhere else on Dartmoor; laid down 350 million years ago by living coral reefs. The rock was treated in nearby lime kilns with alternate layers of limestone and charcoal (from coppiced hazel trees), which was lit at the bottom and burned at high temperature for three days. The lime was used for treating fields and soils in farming to "sweeten" the land. The pool is deeper than the nearby Meldon Viaduct is high: the pool is around 40 metres (130 feet) deep, the tallest viaduct span is 120 feet.

Devon & Dartmoor HER - MDV4826 - Meldon Lime Works - a lot of detail: e.g. Okehampton Lime and Cement Quarries Company Limited was formed in 1880, probably on the east bank of the river. There were two small quarries that supplied the lime kiln to the north. The kiln is built into the side of an earlier quarry (that was "totally abandoned in 1808 but re-opened in the 1840s"). Quarrying transferred to the west bank in 1839. The quarry expanded in the period 1885-1905 - waste was being transferred across the river by 1885. The OS 25-inch England & Wales 1892-1914 Series map shows an embankment running north from the waste tips on the east side of the river to the gate to the site where waste might be removed.

 

View across Meldon Pool. Early in the Carboniferous Period, around 350 million years ago, the Variscan Orogenyeny occurred, when the Atlantic tectonic  plate collided with the European plate. This climaxed with the intrusion of the molten magma of the Dartmoor granite. Oceanic sediments were pushed up, folded and baked with the tremendous heat of the process. The rocks around the granite were changed and are referred to as the metamorphic aureole. - Meldon is entirely within this region. Super-heated fluids leaked from the granite into the metamorphosed rocks of the surrounding country rocks to form new minerals. Source: Peter Keene (2007), "Exploring a Dartmoor Valley", DNPA & Devon County Council.

 

The surface exposure of dark limestone sandwiched between layers of hard flinty chert.

 

View from the north end of the Pool.

 

"Quarry" (bottom left quarter) on 1841 Okehampton Tithe Map, Copyright Devon County Council. The limestone quarry was smaller pre-1841 with various buildings around it that disappeared as the quarry became larger.  Beyond the buildings, an inclined plane can be seen extending northwards beyond the buildings to take stone to the kiln.  NB - on the Tithe Map, the quarry is 1/3rd way in from the LEFT & 1/4 way up, to its RIGHT is a big tear with the "O" of "Okehampton" to the right of the tear.

 

Devon & Dartmoor HER - MDV120246 - Weigh House and weighbridge south of the Meldon viaduct - this was a ruin but is now being rebuilt. The cast iron weighbridge is in the ground in front of the building ....

 

Remains of the weighbridge, made by Bartlett & Son, Bristol and Bartlett & Son in Grace's Guide to British Industrial History.

 

The west lime kiln beside the track just north of the Pool, SX 56425 92261, its rear furnace chamber now blocked. Built 1880-1885, certainly post-Tithe Map (1841), because only the kiln across the river is shown. Ccharcoal was made here from the surrounding woodlands until the train came with cheaper fuel, coal. The limestone was roasted in alternate layers using charcoal to convert it fom calcium carbonate into quicklime, calcium oxide (CaO).  This would be slaked with water and then powdered to form slaked lime (calcium hydroxide, CaOH) to put on land to raise the pH and increase its fertility. The stone and charcoal were lifted to a loading platform at the top of the kiln using an inclined tramway from the quarry. The charge was lit through the grate at the back of the kiln and after three days, the lime was shovelled out through the same grate into waiting carts. The limekiln was disused by 1905. Source: Peter Keane (2007), Exploring a Dartmoor Valley: The Meldon Beneath Our Feet, DNPA & Devon County Council, page 17.    

 

  

An unusual feature are the two small recesses in the walls of the main chamber, one of which is seen above .....

 

The blocked-up grate .....

 

This photograph was an attempt to show what is left of the inclined plane from the back of the kiln running back to the quarry (Pool), but the vegetation makes this hard to see.

 

Scene showing the weighbridge (right) and the kiln (left) and a gate leading to the track underneath the viaduct .....

 

Meldon Viaduct, from the website .....

"Meldon Viaduct, a Scheduled Ancient Monument, is a superb example of Victorian Engineering and is one of only two in the country of this type of construction. Built in 1874 for the London and South Western Railway main line between Waterloo and Plymouth, it was widened to double track in 1878 and closed to trains in the late 1960s.

The widening was achieved by constructing a second viaduct along side the first, using an almost exact copy of the original design. Over the years the two structures have been tied together in an effort to reduce sway when trains crossed the viaduct. The structure underwent a major refurbishment in 1996. Although the trains have long gone it is still a significant landscape feature that it is now available to walkers and cyclists."

The viaduct crosses the narrowest part of the gorge. The sheer cliff on the left bank of the river is known as Burrow Cleave - the term cleave actually applies to this type of feature rather than a steep-sided valley. Source: Mike Brown (2001) Guide to Dartmoor, CD-ROM, Dartmoor Press, Grid Square 565 923.

 

Meldon Viaduct and a more modern description: The London & South Western Railway Co. from Exeter reached Okehampton in 1871. It was extended as a single track as far as Lydford in 1874 and this involved building the viaduct, spanning the river for 165 metres. The original viaduct was built of wrought iron and it was riveted. The line was extended to Plymouth and the track was doubled in 1878, with a second viaduct being made of welded mild steel. The viaduct is a Scheduled Ancient Monument.

 

SX 56336 92436 - an important turning off the main track to reach the next clam bridge over the river. Easy when you know where!

 

Bluebell, primrose and celandine.

 

Wood anemone, Anemone nemorosa.

 

A second footbridge at SX 56465 92734

 .....

 

View down the West Okement River.

 

Bluebells in Meldon Woods, above the road above the footbridge.

 

Common bluebell, Hyacinthoides non-scripta .....

 

Bluebell.

 

Part of the viaduct supports.

 

Gate off the road at SX 56485 92328. Around to the left is the early lime kiln, to the right is a bank that supported a tyramway to the gate for bringing out old waste from the finger dumps, and down ahead is the Turbine House. The possible crushing house feature (seen below) is just out of sight on the right in this image ......

 

The (east) lime kiln here, SX 56500 92266. was shown on an estate map in 1790, serving two small quarries a little south, by the river. It was abandoned in the early 1800s but is said to have been brought back innto use brought back in use when quarrying started on the west bank  - but the west bank quarry (now Meldon pool) is shown on the 1841 Okehampton Tithe Map. The history is convoluted ..... 

 

Lime kiln east, built before an Okehampton Estate map of 1790 and originally serving a small nearby quarry. It became disused but was used again when the Meldon Pool quarry started up. This is earliest building in the valley to exploit the local geology. The view is partially blocked by an inclined tramway that took quarried stone up to the railway viaduct (which was built in 1874).  Source: DNPA Meldon Case Study: Information Sheet 3B: Quarrying - Limestone.  

The ramp is part of a later incline up to LSWR sidings at the eastern end of the viaduct.
Devon & Dartmoor HER - MDV120326 - Site of crushing sheds at Meldon Limestone Quarry

 

The open fire grate ..... through which can be seen the floor of the large "well" at the back of the kiln that was loaded from the top .....

 

After crawling inside the grate, this is the view up the "well" or "chimney" where the charge of layers of limestone and charcoal would have been tipped before burning (this being a three-day operation). 

 

This feature, a piece of wall, is built into the tramway bank between the kiln and the turbine house - this may be part of the crushing house where waste was brought from the finger dumps to be crushed and taken past the kiln by tramway up to sidings for use as ballast on the railways. Again, there is little known about this undertaking.

 

Devon & Dartmoor HER - MDV120311 - Turbine building at Meldon Quarries

A small stone and brick building on the east bank of the river, at SX 56476 92166, is the Turbine House that provided electricity for the quarry.  Water flows in as a small stream - no doubt reduced compared to when the place was working - and out via a channel in the back wall. Meldon Dam can be seen behind.

 

  

A small flow of water runs naturally into the building.  No doubt is was properly piped with a much greater flow when the turbines were in situ.

 

The floor inside the building .....water exits at top right .....

 

The window above the water exit .....

 

I have no idea what the girder, hook and steel cable were for, perhaps they worked as a crane?

 

The brick-lined channel from the back of the turbine house to the river.

 

Another view of the turbine house; the raised, grassy bank behind is the embankment alongside the river that would have carried wagons brinding waste material from the quarry either for crushing for railway ballast (and road building?) and transportation away.

 

Devon & Dartmoor HER - MDV120326 - Site of crushing sheds at Meldon Limestone Quarry

Somewhere in the vicinity of the turbine house there were corrugated iron buildings that housed crushers where the previously unwanted waste rock that had to be quarried to get to the limestone was crushed and loaded into to wagons operating on a separate incline leading to the LSWR sidings on the eastern edge of Meldon Viaduct. This incline is the earthwork partially obscuring the mouth of the early lime kiln

 

General view between the turbine house and the aplite quarry buildings.

 

A small pixie bridge (SX 56491 92162) across the stream just above the turbine house (this was destroyed before the day of the walk).

 

The explosives magazine, SX 56550 92162 .....

 

The magazine, seen from the spoil heap above it - the walls are thick but the roof was probably flimsy in case of an accident ..... the rockface at Meldon Pool can be seen behind .....

 

An anchotage device?

 

This ringed-pit at SX 56518 92088 maybe the mine shaft recorded in the HER record below .....


Devon & Dartmoor HER - MDV120322 - Mine shafts east of Meldon Pool
There are mine shafts on the east bank of the river with two adits nearby, typical of tin mining. They exist as sub-circular hollows with rims of upcast soil on their downslope margins. They vary in diameter, most examples being in the area of 3.0 metres with one exceptional example of 6.0 metres.  Turning and looking in the opposite direction .....

 

Another view of the "finger" dumps - all the "waste" from the old quarry must be the cherts that was surrounding the limestone.

 

These trees are growing in a pit, at SX 56661 92136, part of a tin-working gert running down towards the river. The gert ends at SX 56589 92163 where a spoil heap starts and ends closer to the river at SX 56562 92171, quite high above the surrounding ground.

 

Trees growing in the gert.

 

On the second reconnaissance walk, the car park at the "far" end of the site was visited, at SX 56737 92136, behind the modern building, where this sign is located. Click the image to see a larger version.

 

 These concrete buildings at SX 5668 9204 are associated with the recent quarrying after the glass factory closed in 1921 - the site remained open for a further fifty years (about 1970) to provide material for road metalling.

Information Sheet: The Dartmoor granite and associated igneous rocks (downloadable PDF file)

 

Devon & Dartmoor HER - MDV17703 - Glass factory Meldon Quarry

DNPA Meldon Case Study - Information Sheet 3F: Glass making - Meldon Aplite Quarries (downloadable PDF file)

The Bottle Factory - from the late 19th century, investigations were being made concerning the production of granulite at Meldon. There seemed to be potential to establish both glass and china works at the site. There was little activity until 1920 when  a syndicate from London decided to build a glass factory. Two furnaces were being installed (of a planned 12) and about 500 men were required (Western Morning News 29/03/1920. However, by February 1921, the men had been laid off and new owners were being sought. No obvious features remain of a glass industry, but large amounts of broken glass fragments can be seen, mostly representing small medicine and cosmetic bottles. The glass manufacturing area seems to have been to the west of the northern aplite quarry. Another possible location could be the levelled areas south-east of the modern gateway (developed after 1948).

 

The ruined scales for the weighbridge.

 

A view up the Red-a-Ven Brook.

 

The track towards Meldon Dam, with the southern aplite quarry (left) and the ruined pier of a bridge (right) .....

 

A short distance down the Red-a-Ven Brook from the buildings are the ruins of the piers of a bridge which once spanned the brook and which carried a short tramway from the quarry to the now-disappeared works .....

 

Just below the bridge abutments there is a small building.

 

Looking into the southern aplite quarry at SX 5663 9195 ..... Click the image to see a larger version .....

 

The far end of the aplite quarry where the aplite vein disappears into the ground .....

 

Aplite - stripew rock as seen in the old quarry that is now Meldon Pool.

 

Another view of the viaduct.

Today's group, a little fewer being Cup Final Saturday?

 

View from the track at SX 56542 91972 where the older wheelpit and footbridge are visible (zoomed view).

 

The path to Meldon Dam .....

 

The viaduct, from the same spot .....

 

Meldon Dam .....

 

The system for the spillway to control overflow when the dam is full: this appears to be a combination of a straight chute and stepped spillway features. These are designed to reduce the kinetic energy of overflowing water and thereby reduce erosion damage. This sytem is essentially an uncontrolled system in that there are no mechanical gates or vanes to regulate the rate of overflow at the top of the dam. If you want more information about spillway design, then try THIS.

 

The viaduct seen from the fence at the end of the dam .....

 

Zoomed view of the viaduct .....

 

 

View at the south-east end of the dam .....

 

View along the dam .....

 

Surveyor's theodo;ite pillar at the end of the dam; there is another at the other end of the dam and these were used to check dam alignment and curvature .....

 

From the pillar .....

 

The reservoir, from the middle of the dam .....

 

 

The curve on the north-east half of the dam, from the middle .....

 

Looking down on the spillway system ..... designed to reduce the force of the overflow .....

 

The triangulation pillar at the north-west end of the dam .....

 

Plaque commemorating the opening of the dam on 22 September 1972 .....

 

Last look at the dam, on the way back to the car park.

 

Walk details

MAP: Red = GPS satellite track of the walk.

© Crown copyright 2016  Ordnance Survey Licence number 100047373
Also, Copyright © 2005, Memory-Map Europe, with permission.

 

This walk was reached from the Tavistock direction by following the A386 out through Mary Tavy and SDourton, joining ther A30 dual carriageway, taking the Okehampton sign, turning right at the end of the sliproad to "Meldon", following this road through the village and turning left immediately after passing under an old railway bridge. At the end of this road, turn left into the car park - at the yellow cross symbol. Ignore the  P  symbol on the map.

 

Statistics
Distance - 3.88 km / 2.41 miles 

 

All photographs on this web site are copyright © Keith Ryan.
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