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.
During the 1830s, chemists discovered that nitric acid applied to wood fibres, paper or starch could produce explosively combustible 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.
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 sceptical 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.
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.
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 shock wave are known as high explosives. This shock wave, 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.
Nitroglycerine was first synthesised 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".
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 shock wave 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.
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.
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.
Some of the enclosures of the National Explosives Works contained plants to produce gelignite for blasting in mines.
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".
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.
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.
Other enclosures contained "cotton drys". These were where guncotton dried out.
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.
The folklore about magpies collecting shiny objects has been shown to be an incorrect myth. A scientific study found that magpies are actually scared of shiny objects and actively avoid them.
The high point in the dunes is where nitroglycerine was manufactured. The original centre for nitroglycerine manufacture was known as Jack Straw's Hill.
Much of the Towans dune system is designated a Site of Special Scientific Interest), noted for both its geological and biological interest, and includes a nature reserve managed by Cornwall Wildlife Trust. The dunes and grassland provide a habitat for plants including the pyramidal orchid and a rich butterfly population which includes one of the largest UK populations of the silver-studded blue. Other wildlife includes skylarks, adders and even glow worms.
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.
The walk continues ahead on the well-worn path.
First, you may want to climb to the top of "New Nitro Hill" to admire the view before continuing the route.
From the bottom of the incline, follow the path until you reach a well-worn path departing to the left through a V-shaped valley between the dunes.
As the name implies "New Nitro Hill" took over from Jack Straw's Hill as the principal location for nitroglycerine production. 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.
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 grease-proof 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.
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.
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.
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.
Ragwort is fairly easy to recognise as a relatively tall plant with yellow flowers standing above surrounding grass.
Ragwort was rated in the top 10 nectar-producing plants in a survey for pollinating insects on UK agricultural land. The plant has also become known as "Benyon's Delight" following Facebook comments describing it as a "vile poisonous weed" by Richard Benyon, the then government minister responsible for biodiversity.
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.
A spring on the towans known as the Boiling Well was documented in mediaeval times and believed to have healing properties.
By Victorian times, a mine had been established, known as Boiling Well Mine or Wheal Boil and the spring now rises into the main drainage adit of the mine rather than above ground. Between 1821 and 1856 there are records of the mine producing copper, lead and zinc as well as some silver and there are around thirty shafts dotted around the towans.
After the mine closed, the clear water from the spring was used in the production of nitroglycerine.
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 inoculated with a live virus have the potential to transfer the vaccine into the wild population which may further increase resistance. Consequently the peak rabbit population gradually recovered to around half the size of the UK human population.
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.
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
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.
On Gwithian beach, rails and a mine cart can be seen protruding from the cliff. This was part of tin sand-works. The Red River was used by mines to discharge their waste water and this contained small particles of tin ore. These washed down the river and accumulated in the sand. Due to longshore drift, carrying sediment from the river mouth, the highest concentration of tin was around the point where the cart is. However, the processing was done on the other side of the beach beside the river where the water provided a source of power. Initially, sand was carried across the beach by horse but in the early 20th Century, an aerial ropeway carrying buckets was built on pylons across the beach to move sand more quickly. This was further improved by creating a tunnel down the the beach from the cliff top, so carts containing sand could be raised to the cliff top from which a more efficient ropeway could operate that wasn't dependent on the tides. It's thought that the cart dates from the 1920s or 1930s and was abandoned when the works closed at the start of World War 2.
Cornwall Wildlife Trust was founded in 1962 as the Cornwall Naturalists' Trust and was run entirely by volunteers until 1974. It was renamed in 1994 as part of a national initiative to unify the names of wildlife trusts across the country. It now manages over 50 nature reserves and has over 17,000 members with over 1,000 active volunteers.
There's a volunteering section on the Cornwall Wildlife Trust website which includes lots of marine activities as well as things in the nature reserves.
Pyramidal orchids prefer sunny spots with dry soils which makes areas of disturbed ground such as roadside verges and old workings an ideal habitat. They are recognisable from their bright pink flowers in summer forming a dense pyramid or ball-shaped cluster at the top of the stem.
Viper's bugloss is a fairly tall plant with hairy leaves and a spike of blue funnel-shaped flowers in mid-late summer.
The quirky name is based on it's appearance. The leaves are likened to an ox's tongue (bugloss is based on Greek words for ox and tongue that came through Latin and then French). The viper element is less obvious but suggestions include the flowers or fruits resembling a snake's head (the German name for it translates to "common viper head").
Contact with the hairs on the plant can cause dermatitis so it's best to avoid touching it.
European privet is a native deciduous or semi-evergreen shrub with smaller leaves than garden privet and forms a bush up to about 3 metres tall. Its black berries are poisonous to humans but an important food for thrushes which disperse the seeds.
The fully evergreen privet which is now the UK's most common garden plant was introduced from Japan in Victorian times. In Elizabethan gardens, the native privet was used for hedges.
In late June and July, lady's bedstraw produces clusters of tiny pale yellow scented flowers. The plant has long, thin stems with a star of very narrow leaves at intervals along the stems, a bit like rosemary, or its relative, goosegrass, but is softer than either.
The name has arisen from its use to stuff mattresses as the scent was pleasant and also repels fleas. In Scandinavia, the plant was used as a sedative during childbirth. The plant was also used to produce red and yellow dyes. The light orange colour of Double Gloucester cheese originates from this. The flowers were used in place of renin to coagulate milk but no records remain for the method of how to do this.
Common agrimony is a native plant and a member of the rose family. It prefers less acidic soils which limits its range in Cornwall but can be found in a few places along the coast. It is recognisable by yellow 5-petal flowers on a spike which gives rise to another of its common names: "church steeples". It is also known as sticklewort as the seeds have burs that stick to passers-by. The leaves have distinctive toothed edges rather like a saw blade.
Wild thyme grows along the coast and flowers from June to September with tiny pink flowers. During mediaeval times, the plant was a symbol of bravery, possibly due to derivation from the Greek word thumos, meaning anger or spiritedness. An embroidered motif of a bee on a sprig of thyme is said to have been given by mediaeval ladies to their favoured knight.
Coastal land management including removal of excess gorse and grazing to keep taller plants in trim has allowed wild thyme to become more widespread as well as the Cornish chough. Wild thyme is a nectar source for many bees and butterflies and the food plant for young caterpillars of the large blue butterfly.
The orchids are one of the largest families of plants with over 28,000 recorded species, many of which live in the tropics. It is thought that the first orchids evolved somewhere between 80 and 100 million years ago. The word "orchid" comes from the Greek word for testicle on account of the shape of the plant's tuber. Consequently, in mediaeval times, the plant was known as bollockwort.
A fuel such as petrol or wood needs an oxygen supply to burn. Carbon dioxide, foam or powder fire extinguishers remove this to put out the fire.
Explosives don't. They have their own built-in oxygen supply which is why many can even be used underwater.
When explosives burn, lots of gas is released quickly which creates a high pressure. The force from this being released can be used to break tough materials such as rock, hence the usefulness in mining.
Nobel realised that although nitroglycerine could not be detonated by a fuse, a small charge of gunpowder ignited by the fuse would generate enough energy to start off the nitroglycerine. This small charge of a more easily combustible explosive is known as a detonator.
He soon replaced the gunpowder with more sensitive mercury fulminate which was already in use for the firing caps in gun cartridges.
Within a few years, electrical detonators had been developed which used a thin strand of wire which would glow and ignite mercury fulminate explosive which could then be used to detonate dynamite.
A portable power supply was created with a T-handle (as seen in Roadrunner cartoons) that pushed a rack-and-pinion mechanism to spin a tiny generator to create a spark.
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