Foxgloves are reliant on bumblebees for pollination and bumblebees are much more active when the weather is good. Partly, as an insurance policy against bad weather, foxgloves have evolved to stagger their flowering over several weeks, starting with the flowers at the base of the stalk and working up to the top, where the higher flowers protrude over other vegetation that has grown up in that time.
This stretch of the route is on the waste tips of the Trethurgy China Clay works. This operated from the early 20th Century, first recorded on a map from 1930. The disused pit is now used as a fishing lake and much of the waste tips have now been colonised by bushes.
China clay in Cornwall and Devon resulted from a sequence of events that began over 300 million years ago; molten rock cooled into granite: a mixture of quartz, feldspar and mica. As it cooled, the feldspar reacted with other minerals to form china clay.
The clay from Cornwall was found to be a much finer quality than elsewhere in Europe and also turned out to be the largest deposit in the world. By the mid-19th Century, 7,000 workers were employed in the St Austell area alone and by 1910, Cornwall was producing 50% of the world's China Clay.
At the time of writing, the UK is still the third largest producer of China Clay in the world: Cornwall produces approximately 1 million tonnes of kaolin each year. Due to increasing mechanisation and large amounts of production being moved to Brazil, the industry now only employs around 1000 people.
The word kaolin is thought to be a corruption of the Chinese for "high ridge" where it was presumably found.
Red campion is also known as "red catchfly". The flowers are an important nectar source for larger pollinating insects including butterflies, bees and hoverflies. Much smaller flies drawn to the nectar can become stuck in the froth on the stigmas of the female flowers but this is not intentional by the plant (it doesn't eat them).
The pure white porcelain used by the Chinese was discovered millennia ago and has always been a valuable material, appearing in many stately homes. Despite many attempts to find it elsewhere, it remained elusive until a few deposits were found in parts of Europe and in America early in the eighteenth century.
In 1746 William Cooksworthy noticed the miners repairing the furnaces with clay at Great Work Mine and how this was fired by the furnace. He developed a way to process the clay to separate the kaolin from the gritty rock and fire this into fine porcelain.
The extraction of china clay has dramatically altered the Cornish landscape: it is estimated that 120 million tons have been extracted. For every 1 tonne of china clay, there are 9 tonnes of mineral waste products (a gritty sand of quartz and mica), which has led to the creation of large areas of tips. The now disused conical (or "sky tips") can be seen near St Austell from as far away as Bodmin Moor.
Due to the density of china clay pits, the area around St Austell has become known as "The Clays". This has dominated St Austell's more recent industrial history and to some degree masked the area's earlier history: prior to china clay, St Austell was an important centre for copper and tin mining.
Sorrel is native to the UK and common in fields and hedgerows. It's salt tolerant so it can often be found on the coast in Cornwall. The leaves resemble small, narrow dock leaves. In summer the plant is often evident in abundance in fields by its red seeds at the top of a tall stalk.
In common with many vegetables, sorrel contains oxalic acid. Exactly how much is a bit unclear: many articles mention "high amounts" though some published studies report a lower percentage than in spinach, parsley or rhubarb, though don't specify how easily soluble the oxalic acid is in each case. Oxalic acid is poisonous if enough is consumed and prolonged exposure can cause kidney stones. It's therefore a good idea not to eat foods high in oxalic acid every day or in very large quantities.
The path to the left is private and continues to Vounder Farm. The settlement of Vounder was first recorded in 1354 as Bonder. The name is from the Cornish word bounder for lane. That mediaeval lane is now part of National Cycle Route 2.
The National Cycle Network is coordinated by the charity Sustrans. It began with one route in Bristol in 1984 and now consists of around 15,000 miles of signposted cycle routes known as National Cycle Routes. These each have a number and are constructed using a combination of roads typically chosen to have light traffic and some traffic-free tracks which are open to cycles.
Centuries ago, before china clay extraction began, the area would have been moorland. This area is still known as Carvear Moor although the land on the hill had been cultivated for farming by Victorian times when a horse engine was in use at the farm.
Horse engines were the forefathers of the modern-day farm tractor. The horsepower itself either involved a treadmill or a capstan turned by a horse, both of which provided a rotating axle that could be used to drive gears. As with modern-day tractors, a modular approach was often used with the horse-driven power unit being coupled to different pieces of farm machinery to perform different tasks such as threshing or pumping.
The Eden Project was conceived by Tim Smit after his involvement with the restoration of the Lost Gardens of Heligan. Work on the Eden Project began in the late 1990s and the visitor centre opened to the public in May 2000 followed by the main attraction in March 2001. The biomes are effectively giant bubble wrap, with each panel containing an insulating gas bubble sealed within plastic. This allows a tropical climate to be maintained in one where nearly 4 acres of rainforest thrives. The Core building was added in 2005 to provide an education facility which includes classrooms. The Eden Project is run as a social enterprise by the Eden Trust - a charitable trust dedicated to educating the public about the natural world.
The walk continues ahead but first you may want to either visit Eden (to the right) or the café (which doesn't require a ticket) and toilets.
To continue the walk, follow the pavement past the rest of the bike racks and around a corner to another pedestrian crossing. Continue over this to a path marked "All clay trails" and follow this to another pedestrian crossing.
The dandelion-like flowers along the coast are most likely to be catsear, also known as false dandelion. Catsear is very salt tolerant, not only growing along the coast but actually in sand dunes. The easiest way to recognise it is by the hairy leaves, hence the name. If you can cope with the texture, the leaves are edible and are much less bitter than dandelion leaves.
Another way to tell them apart is when they are flowering. Although dandelion flowers over quite a long period, the most profuse flowering is in April and May whereas catsear's intense flowering period is in late June and through July. Catsear has neater flowers than dandelion with squarer edges to the petals (but still toothed). The stems supporting the flowers are also solid, in contrast with the hollow stem of the dandelion.
The Coast and Clay Trails is a 45 mile public access network of tracks and roads around St Austell. The trails were first opened as "The Clay Trails" in 2005 as part of a restoration programme to provide new habitats for flora and fauna. The trails are described as "multi-use" although are principally aimed at cyclists, with many sections of the routes being on Public Highways (quiet lanes where possible) and link up with National Cycle Route 3 to Bodmin and Truro. For walkers, the off-road sections provide some additional links across the Rights of Way network.
The village of Bugle came into existence in the mid 19th century following the construction of a turnpike (toll) road in 1836-7. A coaching inn was built and a small settlement grew up around this called Carnsmerry. In 1842, the settlement was connected to Par via the Treffry Tramways to export minerals from the nearby mines. Carnsmerry eventually just became known by the name of its pub - the Bugle Inn - and disappeared into history.
Genetic analysis has revealed that domestic apples originated from wild apples in Kazakstan near the Chinese border. It is thought that the apple was probably the first tree to be domesticated by humans, several thousand years ago. Wild apples grew in the British Isles in Neolithic times but domesticated apples were introduced by the Romans. Over 7500 varieties of apple are now known.
At the time of writing, the Eden Skywire is Britain's longest zipwire at half a mile in length. The journey takes around 45 seconds and reaches a speed of around 60mph. This is roughly half of the maximum speed that a skydiver reaches in free-fall where 95% of the top speed is reached in just over 10 seconds.
Gunnera looks like giant rhubarb but the leaves stems are spiky. It tends to favour damp places as quite a lot of water is needed to supply its huge leaves.
The plant has a symbiotic relationship with cyanobacteria which live between its cells. The cyanobacteria, also known as "blue-green algae", are photosynthetic and also supply the host plant with nitrogen which allows it to colonise poor soils.
The Eden Project is built in the old Bodelva china clay pit which was worked for over 160 years, and by 1995 was nearing the end of its economic life. The Eden site also encompasses the Carvear china clay works which closed in 1942.
The works are to create a geothermal power source.
For 4.5 billion years, the Earth has been very slowly cooling. Heat that is still left over from the formation of the Earth is supplemented by heat generated by radioactive decay within the Earth. The heat slowly makes it way up to the surface, mostly into the oceans where the crust is thinnest, and then radiates away into space.
By drilling a borehole, down to hotter rocks deeper in the Earth's crust, it's possible to mine for heat. Cool water can be pumped down, and depending on the depth, hot water or steam comes back up which can be used for heating or electricity generation, respectively.
The Eden Deep Geothermal power plant has been designed along the following lines... Water is pumped down a 4km deep borehole. The hot rocks boil this and create superheated steam. This rises up a second borehole and is used to generate electricity. The water from the condensed steam is then re-used to pump back down the first borehole in a "closed loop". After a few decades of intensive extraction, the rocks surrounding the borehole can become locally depleted of heat. This means that some geothermal power plants can have a finite economic lifetime even though over a slightly longer timescale, the local heat supply will be replenished.
Rhododendron is a member of the Ericaceae family to which heathers also belong and like its cousins, it is tolerant of acid soils. The word rhododendron is from the Ancient Greek for "rose tree" due to their spectacular flowers. As a result of these, rhododendrons have been popular ornamental plants for over two centuries and the species that we now call the common rhododendron was introduced in 1763. The plants thrive in the UK climate and were once native but were wiped out by the last Ice Age. Being a vigorous plant, common rhododendron was often used as a root stock onto which more fragile but exotically-coloured hybrids were grafted.
Azalea is a name given to a sub-group of rhododendron species which typically form a bush rather than a large tree. There is no clear biological distinction but most azalea species are deciduous (whereas rhododendrons are evergreen) and azaleas often have smaller leaves, funnel-shaped flowers and are more tolerant of sunny locations than rhododendrons.
Rhododendrons are so successful in Britain that they have become an invasive species, crowding out other flora in the Atlantic oak woodlands. They are able to spread very quickly both through suckering along the ground and by abundant seed production. Many of the root stocks of ornamental specimens have suckered off some new common rhododendrons which have then out-competed the ornamental tree and killed it off!
Conservation organisations now classify the rhododendron explosion as a severe problem and various strategies have been explored to attempt to stop the spread. So far, the most effective method seems to be injecting herbicide into individual plants which is both more precise and effective than blanket cutting or spraying.
A problem with rhododendrons is that they kill bees. Rhododendron nectar is highly toxic to honeybees, killing them within hours. Some other bee species such as mining bees are also adversely affected. Bumblebees seem to be unaffected though.
Honey made with rhododendron pollen can be poisonous to humans, causing severe low blood pressure and low heart rate if enough is eaten. Rhododendron honey is used in Nepal as a hallucinogenic drug.
The blackbird is a species of thrush. The name "blackbird" is mediaeval, first recorded in 1486. Since most of the crow family is also black, plus many seabirds, the choice of this particular species for the name is thought to be due to its size. Up to the 18th Century, larger birds such as crows were referred to as "fowl" and the term "bird" was only used for smaller species.
The Old English name for the blackbird was osle and up to the 17th Century this survived as in alternative names for the blackbird ranging from ouzel to woosel. One of these is used in A Midsummer Night's Dream by Shakespeare: "The Woosell cocke, so blacke of hew, With Orenge-tawny bill".
Only male blackbirds are actually black. The females are brown. The difference in appearance between males and females is known as sexual dimorphism and is an evolutionary strategy by the males to get noticed more by females at the cost of decreased chances of survival.
Blackbirds can be found in deciduous woodland, particularly where there is dense undergrowth. In the man-made landscape, hedges provide plenty of dense undergrowth and have consequently become a really important habitat for blackbirds. Moreover, many gardens have such a high density of hedges and bushes that they are able to support ten times the blackbird population versus an equivalent area of their natural woodland habitat.
Blackbirds are one of the most common birds in the UK with a population of somewhere between 10 and 15 million. However, blackbirds were in steady decline from the 1970s through to the mid-1990s. The population has only relatively recently recovered.
Blackbirds begin singing from around the end of January but it is normally the overkeen young males initially - the older, wiser males wait until March, pacing themselves for the singing period which continues into the early summer. Blackbirds have been shown to sing more during and after rain but exactly why is not yet known.
Baby blackbirds usually leave the nest before they can actually fly then hop and scramble through the bushes. Their parents watch over them so don't attempt to rescue them.
Blackbirds in the UK are resident all year round but the blackbirds that live further north (e.g. in Norway) migrate south for the winter. To help with migration and also to avoid being eaten by predators, blackbirds can sleep half their brain at a time. This allows them to get some rest whilst still maintaining enough alertness to fly or spot predators.
The reference in the nursery rhyme "sing a song a sixpence" to "four and twenty blackbirds baked in a pie" is thought to be to the 16th Century amusement (though not for the blackbirds) of producing a large pie which included an empty chamber. After the pie had been baked and was ready to be served, a trapdoor would be cut in the empty chamber and live birds were placed inside which would fly out when the pie was cut open. Live frogs were sometimes used as an alternative.
In the Christmas carol "The Twelve Days of Christmas", the line "four colly birds" is thought to be from 18th Century slang meaning "black as coal" and was a popular nickname for the blackbird. Whilst many people today sing and write "four calling birds", this is thought to be a modern misunderstanding of what was originally written.
Robins are able to hover like kingfishers and hummingbirds and use this skill when feeding from bird feeders, which they are unable to cling to.
Robins are also able to see magnetic fields. Receptors in their eyes make magnetic fields appear as patterns of light or colour which allows them to use the Earth's magnetic field for navigation. They only seem to use their right eye for this as the left half of their brain (linked to the right eye) does the processing.
Unlike many birds that just sing in spring, robins sing nearly all year round. In fact during winter if you hear birdsong, it's most likely to be a robin. Despite how cute robins look, they are actually very territorial and the chirp is an aggressive warning to any would-be intruders not to even think of trying it. When robins don't sing, this a sign that their body fat reserves are low and they are conserving what little they have left until food becomes more plentiful.
The tradition of robins on Christmas cards is thought to arise from Victorian postmen wearing red jackets. Consequently they were nicknamed Robins.
The Cornish name for the bird is rudhek from rudh = "red" (in Cornish, "dh" is pronounced like the "th" in "with"). Cornish place names like Bedruthan, Ruthern and Redruth are all based on the colour red.
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.
Although it has become a pejorative nickname for tourists, the term "emmet" (from a Cornish dialect word for ant) was originally used quite generally to refer to a crowd of people seen from a distance. In the 18th and 19th centuries, the quarrymen scaling the cliffs on ropes were referred to as emmets. In Victorian times when tourism to Cornwall became popular, the term was also applied to the tourists on the beaches, seen from the cliffs. As quarrying either became uneconomical or mechanised, the large numbers of workers on the rock faces vanished and now use of the term for tourists is the only one surviving.
Prior to Victorian times, visitors had been coming to Cornwall in small numbers for hundreds of years and consequently the Cornish language also contained a pejorative word for the less gracious of these: tervyajor, which transliterates to "tumultuous voyager" i.e. "disruptive visitor".
The "greenhouse effect" is often thought as trapping heat from the sun reflected from the surface of the earth but most heat rises from the earth's surface in convection currents (thermals). It's quite high in the atmosphere where heat starts to be radiated away into space as infrared. Up here it's pretty chilly as greenhouses go - around minus 18 Celcius! "Greenhouse gasses" are chemicals that absorb the (quite long) infrared wavelengths that are being emitted by this cool matter. They then re-emit this in all directions but some of that ends up going back down towards the earth, reducing the rate at which heat escapes.
Solar panels work by a particle of sunlight (photon) knocking off a charged particle (electron) from one of the chemicals in the panel, leaving behind an oppositely-charged particle missing an electron. These freed electrons can be captured by an electrode and sent on a little journey before returning to the solar panel to fill in the holes where other electrons have been knocked off by sunlight. That little journey of the electrons is what we call "electricity".
Solar panels are usually able to process 15% to 22% of the sun power into usable energy and have a lifetime of about 25 years. Improving efficiencies and the falling costs of production has made solar power one of the cheapest forms of energy.
One large house needs around 25 square metres of solar panels (16 panels) to supply the power used. Smaller, energy-efficient houses can reduce this by about half.
Solar panels absorb visible light so provided it's not dark, they are able to generate power even when it's cloudy. Solar panels are more efficient in cooler temperatures than warmer ones, so cold, sunny winter days generate a comparable level of electricity to hot summer days despite the sun being weaker.
The bicycle was invented in the 19th Century, initially without any form of propulsion - pushed along with feet and free-wheeled downhill.
By the 1840s, pedals had been fixed to one of the wheels resulting in propulsion albeit difficult to control - in 1842 a gentleman in Scotland "bestride a velocipede... of ingenious design" was fined five shillings for knocking over a young girl.
By 1885, bicycles with a chain drive and pneumatic tyres resembling modern bicycles were being manufactured in England. These were known initially as "safety bicycles".
More than a billion bicycles have since been produced and since the 1970s the production of bicycles has increased substantially above that of cars - there are now more than double the number of bicycles produced than cars each year.
1000 Millennium Mileposts were funded by the Royal Bank of Scotland for the National Cycle Network. The cast iron signposts come in four designs:
China Stone is a term used to describe granite which has partially decomposed, but not all the way to china clay. Porcelain can be made by mixing china clay (kaolin) with ground china stone and then melting these together in a kiln to form the ceramic. The china stone lowers the melting point and forms a less crumbly and more glass-like structure. In fact, pure kaolin alone is pretty much useless for making ceramics.
After much trial and error in finding suitable sources of china stone in Cornwall, a patent was filed in 1768 for the manufacture of porcelain using entirely Cornish materials; previously this was only available from China. China stone is consequently also known in some parts of the world as "Cornish Stone".
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