Gwithian and Upton Towans

A circular walk around the nature reserve in the sand dunes that was once the National Explosives Works where young girls manufactured dynamite from nitroglycerine, two tonnes of which denotated causing a shockwave that broke windows in St Ives and Penzance and could be heard on Dartmoor.

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The route is within the huge expanse of dunes running towards Hayle from Gwithian. The initial and final parts of the route are within the natural landscape of Gwithian Towans area whilst the middle section is around the remains of the National Explosives Works at Upton Towans which has been reclaimed by nature and is now a Nature Reserve managed by the Cornwall Wildlife Trust.

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Vital statistics

  • OS Explorer: 102
  • Distance: 2.4 miles/3.8 km
  • Grade: Easy-moderate
  • Start from: Grassy area beside car park
  • Parking: Gwithian Towans car park TR275BT. Turn off the A30 at the Loggans Moor and turn right at the double roundabout signposted for Portreath and Upton Towans. Follow the road until you reach a junction on the left signposted for Gwithian Towans. Turn left here and pass 2 small car parks to reach the main car park.
  • Recommended footwear: walking shoes

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Highlights

  • Vast sandy beach stretching to Godrevy
  • Views over St Ives Bay
  • Wildlife in the nature reserves in the dunes
  • Industrial heritage including the history of high explosives
  • Can be combined with Hayle Towans walk via a very short drive

Directions

  1. Facing the sea, make your way to the Gwithian sign in the bottom-left corner of the car park. Head across the undulating area covered with short grass towards the large mound covered with long grass. Then bear left slightly to keep the mound on your right and follow around the side of the mound to reach the back.

    German miners (whose traditional outfits now appear on garden gnomes) introduced the use of gunpowder for mine blasting in Cornwall in 1689 (as well as gnomes). This was first carried out in one of the mines of the Godolphin estate, quite possibly Great Work Mine.

    Gunpowder represented a great technological breakthrough, as beforehand, rocks had to be cracked by heating and rapid cooling, or by soaking wooden wedges in water. An amount of granite that would take 6 days of work to break with a pick could be broken in one blast.

  2. From the far side of the mound, follow the gently climbing path ahead heading inland very slightly until you reach a crest.

    During the 1830s, chemists discovered that nitric acid applied to wood fibres, paper or starch could produce explosively combustable materials but these were too unstable for any practical use. After the spontaneous combustion of a drying apron in 1846 after an accidental spill of nitric and sulphuric acid, guncotton was discovered by Christian Schönbein. It was found that this could be stored and transported much more safely by keeping it damp and only drying it out just before use.

  3. Once over the crest, continue ahead around the left side of the depression then over the lowest point of the next crest to join the narrow path leading ahead from the far side.

    In 1846 the Royal Geological Society invited Christian Schönbein to demonstrate his recently-invented gun cotton in a granite quarry near Penryn. Quarrymen drilled holes in two large boulders of granite. One they filled with gunpowder and when gunpowder charge was fired, the large boulder split into pieces. Into the hole in the second boulder, Schönbein's material resembling cotton wool was inserted, but only a quarter of the amount used for the gunpowder. The quarrymen were skeptical to say the least. One said he would sit on the hole in return for a pint of beer afterwards, but was persuaded to watch the test first. This turned out to a wise decision as when the gun cotton charge was fired, the second boulder was completely obliterated.

  4. Follow this path over one more crest and continue very slightly to the right for about 20 metres to an elevated area of short grass. Once you reach this, you'll see a well-worn sandy path leading off at 90 degrees to the left.

    When guncotton explodes, it produces six times as much gas as the equivalent amount of gunpowder. As well as being a more powerful explosive, guncotton had a number of advantages over gunpowder for miners: it still worked when damp and even if got completely soaked, it could be restored by simply drying it out. Also the gas produced was relatively harmless carbon dioxide, steam and nitrogen which was a huge improvement over the acidic sulphurous gasses created by gunpowder.

  5. Bear left to take the sandy path leading inland and follow this as it opens out into a wide grassy path. Continue to a fork in the path at the top of the wide grassy area.

    If you've ever wondered why some explosives are called "high explosives" (or even if you haven't, you're about to find out anyway!)... Different explosives burn at different rates. The explosion in a "normal" explosive travels through the material as the heat it generates comes into contact with the next piece. Whilst this is pretty quick, it's not instant and long trails of gunpowder have therefore been used as fuses.

    Materials that burn fast enough to create a supersonic shockwave are known as high explosives. This shockwave, known as a detonation wave, causes very high pressure in the explosive and via a bit of physics this results in a high temperature ahead of where the heat from the combustion has so far reached. The overall result is a chain reaction that travels through the explosive material at a speed of more than a mile per second.

  6. At the fork, take the right-hand path and follow this until the sandy path ends in an area of short grass.

    Nitroglycerine was first synthesized in 1847. It is still one of the most powerful high explosives known with a detonation wave that travels at Mach 30, temperatures of around 5,000 degrees Celcius and an expansion in volume of more than 1200-fold.

    During the 1860s, Alfred Nobel manufactured nitroglycerine as a commercial explosive which was later mixed with gunpowder to create a product called "blasting oil".

  7. Follow along the right-hand side of the grassy area past one path leading towards the sea to join the path leading onto a low bank ahead. Follow this to cross a path running along the top of the bank.

    Nitroglycerine is very shock-sensitive. Being stood in a lab whilst someone hits a tiny drop with a hammer is an experience more unpleasant than you might imagine (a Mach 30 shockwave passing through one's body doesn't feel great at the time or afterwards).

    If nitroglycerine wasn't dangerous enough, over time it degrades into even more unstable compounds. This made it a problem both to transport and store. During the 1860s there were numerous fatalities (including the death of Alfred Nobel's brother) resulting from its manufacture, transport and use that led the transport of liquid nitroglycerine being widely banned.

  8. Continue ahead over the other side of the bank into the sunken grassy area then follow the path to the top of the mound with a gorse bush on the top.

    In the 1860s, Alfred Nobel tried various things to stabilise nitroglycerine including sawdust, coal and cement. Finally he tried a soft rock composed of fossilised algae that can be crumbled into a porous, fine powder known as kieselguhr. Mixed with nitroglycerine this formed a stable clay-like material that he patented under the name "dynamite".

    Over time, nitroglycerine seeps out of dynamite creating crystals on the outside of the sticks or even pools on the floor. Whilst fresh dynamite was relatively safe, dynamite more than about a year old was very unstable.

  9. Pass to the left of the gorse bush at the top of the hill and follow the path down into the grassy area. Cross this to a small gravel path leading from the far side between two banks.

    You are now in the area where the National Explosives Works was located.

    The National Explosives Works was established in 1888, within the dunes of Upton Towans, to supply explosives such as dynamite to the local mines and the area became known as Dynamite Towans. By 1890 the plant was producing three tons of dynamite every day and employed 1800 people. The works was also used throughout the First World War to manufacture explosives such as cordite for ammunition. Production stopped in 1919 and the site was then used for storing explosives before finally closing in the 1960s.

    A number of small enclosures were made in the dunes to house individual buildings interconnected with single-track railways. The arrangement was so that if one plant accidentally detonated, the blast would be deflected upwards so it would not cause a chain reaction, setting off the neighbouring buildings.

  10. Join the path and follow it between the mounds to emerge in an open area.

    In 1875, Alfred Nobel found that by mixing nitroglycerine, gun cotton and wood pulp, he could make a gel that was stable like dynamite. However, the big improvement was that the nitroglycerine did not separate from the other components over time and seep out like it did in dynamite. He called his new explosive with a longer shelf-life "gelignite".

    Some of the enclosures of the National Explosives Works contained plants to produce gelignite for blasting in mines.

  11. Bear left slightly to join a gravel path. Follow this between the banks, over an area of brick and concrete, and round a bend to where the path forks with a grassy path continuing ahead and a gritty path climbing slightly to the right.

    On 4th Sep 1894, an explosion in one of the gelignite plants killed two men when 600lb of gelignite detonated. A 14lb steel axle from the mixing machine was found in the dunes half a mile away and windows were broken in Angarrack.

  12. Bear right to follow the gritty path uphill. Continue following the main well-worn path until it emerges onto a tarmacked path.

    In 1889, an explosive was developed from a mixture of nitroglycerine, guncotton and petroleum jelly. This was dissolved in a solvent and extruded into rods which looked almost exactly like spaghetti and gave rise to the name "cordite". This was a "low explosive" (that did not produce a detonation wave) and was used as a smokeless alternative to gunpowder in ammunition. The burn rate could be controlled via the thickness of the rods.

    Some of the enclosures contained "cordite drys". Once the putty-like rods had been extruded, the acetone solvent was allowed to evaporate so the rods would harden.

  13. Bear left onto the surfaced path and follow this a few paces to a grassy area on the right, immediately after a wooden bench. Bear right slightly into the grassy area and follow the path to the corner of the trees ahead.

    Other enclosures contained "cotton drys". These were where guncotton dried out.

  14. Make your way around the clump of low bushes then join the path curving gently to the right to lead uphill through an area of ivy. One you reach the ivy, climb the steps in the path to reach the remains of a concrete structure.

    Adders live in the dunes and are normally very shy and will disappear at the first sign of activity. During the summer when they have eggs they will stay at the nest and defend it so be mindful of this if you have a dog with you.

    Victorian naturalists believed that female adders protected the young and would swallow them if they were in danger and regurgitate them later. No evidence has been found for any of this. As far as biologists been able to tell, the young adders are left to fend for themselves after they are born. The offspring often remain close to the parents for a few days before they gradually dissipate so it's possible this was misinterpreted as the parents protecting the young.

  15. Continue ahead on the sandy path to pass a sunken area on the left with remnants of concrete foundations and then through the bank ahead towards the chimney to emerge in a fairly level area with short grass. Bear right very slightly across this to reach some steps in the gravel path on the far right-hand side of the open area.
  16. Go up the steps and follow the sandy path to emerge on a stony path.
  17. You can take a short diversion to the left to the chimney, returning here afterwards. The walk continues to the right on the most well-worn path until you reach the mound with a paved incline leading to the top.

    The chimney and brick building are the remains of a factory to produce nitric acid, needed to make the intermediate materials of nitroglycerine and guncotton. The chimney was restored in 1998. The factory floor was constructed from special acid-resistant bricks which were also used to line the flues and the chimney.

  18. Bear left and follow the paved incline to the bushes at the top and continue on the path through these to reach a large concrete structure on the top of the hill.

    The high point in the dunes is where nitroglycerine was manufactured. The bituminous pads were used to support a tramway and pipework also ran up the incline to fill the holding tanks on the top with acid and glycerine. However nitroglycerine could not be pumped along pipes as this could detonate it so was flowed under gravity from the buildings where it was manufactured on the top of the hill into storage vats and downhill again to the buildings where it was used.

  19. Bear right slightly from the corner of the concrete structure towards the sea to reach a path leading down into the dunes. Follow this downhill to where the sandy path ends in a level grassy area.

    An account from The Day newspaper on 5th January 1904 states:

    Four men were killed and several injured by an explosion today in the nitroglycerine department of the National Explosives Works...The whole district was enveloped in a cloud of black smoke and nearly every window in St Ives, three miles from the scene of the explosion, was shattered by its terrific force. Many windows were also smashed at Penzance.

    The explosion is thought to have been caused by a lid dropping into the nitroglycerine in one of the precipitation houses. Almost 2 tons of nitroglycerine detonated as the denotation wave travelled down the flowing nitroglycerine channel to two washing houses. The explosion was reported to be audible as far as Dartmoor. One of the windows in St Ives that was damaged by the explosion was the east window of St Ia Church.

  20. Cross to join the path between the bank and left side of the patch of brambles. Follow the path through a gap in a bank ahead into another grassy area, and follow the sandy path from the other side through one last bank ahead to reach a junction with the remains of a small stone building ahead.

    Rows of small, individually enclosed huts on the site were known as "cartridging huts" where tubes were filled with dynamite or gelignite and wrapped in greaseproof paper, then packed into boxes for transportation to one of the storage huts.

    The workers in the danger areas wore red clothes and many were young girls known as "cartridging girls", operating the machines to fill tubes of dynamite or gelignite.

  21. When you reach the remains of the stone building, turn left and follow the path until it forks to go either side of a large dune.

    Most of the major dunes on the North Cornish coastline are thought to have formed from around 5,000 years ago when sea levels finally stopped rising after the glacial ice from the last Ice Age had finished melting.

  22. Bear right at the fork and follow the well-worn path around the rim of the depression towards a small area of exposed sand. Continue to follow the path through a bank to emerge onto another path beside the remains of a small concrete building.
  23. At the building, turn left and follow the path to reach another (larger) concrete building.

    The buildings used to manufacture explosives were intentionally built from wood so if they exploded, the shrapnel would be much less than from a stone or concrete building. The impact from a flying piece of stone could easily have caused the detonation of nitroglycerine in neighbouring buildings. The concrete remains are from buildings used for storage.

  24. After the larger building, continue ahead to pass one slate waymark (with just an arrow and acorn), then another ahead of it (marked Upton Towans), and finally a third (also marked Upton Towans) after the path bends to the right. Keep left after this to continue following the main path and carry on until the path forks.

    The concrete was made using waste rock from the mines.

    During the early 1900s, concrete began to be used for house construction. Sources of sand and gravel were required and the piles of crushed rock on the mine tips provided a free source of material of the perfect granularity. However, some of this contained small amounts of uneconomic ore such as iron pyrites (fool's gold). This is known locally as mundic which is based on the Cornish words for "beautiful stone". These compounds are formed deep in the earth's crust where there is little oxygen but lots of sulphur. Iron would much rather be surrounded by more pert oxygen atoms so in the presence of air and water, the mundic reacts chemically to form iron hydroxide also known as rust. This is less dense (causing the concrete to expand and crack) and also crumbly. The overall result is that the concrete disintegrates over time and houses can fall down. Within Cornwall, mortgage lenders now require a mundic check to be done on any concrete from the first half of the 20th Century.

  25. Keep right at the fork to stay on the same level and follow the path to another fork.
  26. This time keep left (again to stay on the same level) and pass around the dune on your right. Keep following the well-worn path marked with periodic slate waymarks. Continue past several waymarks with Upton Towans or just arrows until eventually you reach the first slate waymark for Gwithian Towans (leaning over). From here continue a little further to reach a junction of paths.

    Rabbits thrive here given the huge expanse of grass to mow and well-drained burrows.

    Since rabbits' unfussy diet includes pretty much anything grown by farmers, in the 1950s, the disease myxomatosis was deliberately spread in the UK to curb rabbit numbers. Over 99% were wiped-out and they almost became extinct. The few survivors that were genetically more resistant to the disease multiplied and so the survival rate has now increased to around 35%. Escaped pet rabbits innoculated with a live virus have the potential to transfer the vaccine into the wild population which may further increase resistance. The peak rabbit population is now estimated at around half the size of the UK human population.

  27. Keep right then almost immediately left to keep following the path parallel to the beach. Continue past more slate waymarks to reach another with Gwithian Towans inscribed.

    The series of west-facing beaches running from Hayle to Godrevy are particularly favoured by kite surfers due to the large expanse of uncrowded waves. At high tide, the largest beach stretches over two miles from Black Cliff to rocks at Gwithian. North of this, St Gothian Sands lies between Strap Rocks and Magow Rocks at Gwithian. North of the Red River and smaller again is the Godrevy beach, which disappears into several small coves at the highest part of the tide. At low tide, all these beaches combine into one three mile stretch of sand from Godrevy point to the Hayle River.

  28. After the Gwithan Towans marker, continue ahead on the grassy path towards the lighthouse then follow along the right-hand edge of the grassy dip to a slate waymark on the far side.

    The Stones Reef off Godrevy Point has always been a shipping hazard and a lighthouse had been considered for a long time, but nothing was done until in 1854, the SS Nile was wrecked with the loss of all on board. The lighthouse was finished in 1859 and is a 26m tall octagonal tower, located on the largest rock of the reef. The lighthouse inspired Virginia Woolfe's novel "To the Lighthouse", despite her setting the novel in The Hebrides. In 2012, the light was decommissioned and replaced with an LED light on a platform facing the sea. The tower is still maintained as a daytime navigation aid.

    More about Godrevy Lighthouse and Virginia Woolfe in Cornwall

  29. Keep left after the slate waymark to follow along the edge of the mound and then head for the next waymark on the skyline. Follow the well-worn path to return to the car park.

    The best place to access the beach is the path from the opposite end of the car park. Note that there is a dog restriction on this area of the beach during the summer months.

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