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Jeffrey's Pit, located at the top of the road to Trebarwith Strand, is an old slate quarry and was still working in the early 20th century, closing in 1928. Alf Burrell, who lived in Trewarmett and died in the 1970s, started work there as a boy, making tea using the water from the stream. The cutting sheds were on the opposite side of the road (now a house), and as you walk down the road to the beach, the slate tips are walled up on your right. The slate tips cover the stream, which re-emerges below them to continue its path down the valley.
Upstream of Jeffrey's Pit, at the top of Trebarwith Valley, the public footpath runs for a 15-20 minute walk alongside the stream through ancient woodland. Few people go up here, so it's a peaceful spot and a good place to see wildlife. In early spring, you're likely to see frogs breeding in the stream. In April and May, the woodland floor is carpeted in bluebells contrasted by brilliant celandine, primroses and delicate wood sorrel flowers - an indicator that this has been under woodland for a long time.
Bluebells are extremely poisonous, containing a number of biologically-active compounds and were used (probably with varying success) in mediaeval plant medicine. The sap was used as a glue for book-binding as its toxicity repelled insects. It was also used to attach the fletchings onto arrows.
We are so used to seeing sediment in rivers that we've come to accept it as normal but no river should be brown. Sediment is often a product of human activity including eroded river banks, runoff from ploughed farmland and even cattle poaching. It can smother riverbed gravels that are essential for fish spawning. It can also act as a carrier for other pollutants such as heavy metals and pesticides. As well as being toxic, the smell of these chemicals can prevent salmon from detecting their home spawning grounds. That may all sound a bit doom and gloom but the good news is that this damage can be reversed. Pilot schemes of washing and returning gravel to the rivers have had spectacularly promising results, with breeding salmon becoming re-established within just a few years. The Westcountry Rivers Trust are also working with farmers on improving drainage systems to steadily reduce the amount of new sediment and chemicals entering rivers.
In August, blackberries start to ripen on brambles.
Blackberries are closely related to raspberries and technically neither is a berry but an aggregate of many individual tiny fruits, each containing a tiny stone like a miniature cherry.
Trenowth Farm is from the Cornish word noweth and means "new farm". The term is somewhat relative as it dates back to mediaeval times, being recorded as Trenewyth in 1327.
The slate tips on the right are from Trebarwith Road Rustic Quarry.
Trebarwith Road Rustic Quarry is located on the road from Delabole to Trebarwith village. The quarry was originally known as "Jenkins Quarry" and reopened in the 1990s under the new name. As well as rustic slate, Blue Elvan is also quarried here.
Elvan is very hard volcanic rock formed where magma intruded into other rocks to form a (vertical) dyke or (horizontal) sill that cooled fairly quickly, resulting in fairly small crystals. Chemically it is very similar to granite, but in the case of granite, slower cooling resulted in large crystals. Elvans can be seen in many of the churches across Cornwall where it is often used for intricate parts of buildings, such as doorways, so they can be finely carved.
The term "greenstone" is used by quarrymen to describe igneous rocks that, unlike granite, are rich in iron and magnesium and these give it a blue-green colour. When greenstone is formed as a sill or dyke it is sometimes called "blue elvan". This is also quite common in Cornwall and has been quarried for a long time: in the Neolithic period, stone axes made from blue elvan were exported from Cornwall to various parts of Britain.
The group of wind turbines to the left is Delabole Wind Farm.
The Delabole windfarm was the first commercial windfarm in the UK, built in 1991 partly due to local opposition to a proposed nuclear power station which would have been somewhat suboptimal for the tourism on which Cornwall depends. In the 20 years since the Delabole windfarm was first built, the technology improved significantly. In 2011, the 10 original turbines were replaced with just 4 new models which are significantly more powerful and efficient. The cabling for the turbines is all underground and there are no access roads which allows the land beneath the turbines to be farmed.
The Bettle & Chisel is a public house on the main road in Delabole nearly opposite the lane to Pengelly. The pub takes its name from two of the tools historically used by slate quarrymen - bettle is a local dialect word for a lump (club) hammer. "The Bettle", as it's known locally, was, and still is, a favourite hangout of the quarry workers. The bar attests to just how much of a pub can be made from slate!
Delabole Quarry is over a mile in circumferance and was once the deepest man-made pit in the world. It is England's oldest slate quarry; the first written records of a slate order date from 1314 and slate almost certainly from Delabole has been found in prehistoric settlements on Bodmin Moor. Delabole slate is noted for its uniform colour, durability and imperviousness to rain, making it ideal for roofing. There is a visitor centre (open Mon to Fri 8am - 4:30pm) with some interesting historical photos including the Duke of Windsor (then Prince of Wales), plummeting down the tram line into the quarry! Guided tours of the quarry are available at 2pm daily, Mon-Fri from the start of May to the end of August.
The layers of slate in the quarry were eloquently described in 1758: "The strata in the following order: the green sod, one foot; a yellow brown clay, two feet; then the rock, dipping inwards into the hill towards the south-west, and preserving that inclination from top to bottom: at first the rock is in a lax shattery state, with short and frequent fissures, the lamina of unequal thickness, and not horizontal: thus the rock continues to the depth of ten or twelve fathom, all which is good for nothing, and entirely to be rid off; then comes in a firmer brown stone, which becomes still browner in the air; this is fit for slating houses, and the largest size for flat pavement never sweating as the cliff slate, which is exposed to the sea air. This is called the top-stone, and continues for ten fathom deep, the stone improving somewhat as you sink, but not at the best till you come to twenty-four fathom deep from the grass; then rises what they call the bottom-stone, of a grey blue colour, and such a close texture, that on the touch it will sound clear, like a piece of metal. The principal horizontal fissures, which divide the strata, run from ten to fifteen feet asunder; they are no more than chinks or joints, and contain no heterogeneous fossil. The stone of this quarry weighs to water as 2-(62/121) are to 1, is not subject to rot or decay, to imbibe water, or split with falling, as the bottom-stone of Tintagel, and other quarries; but for its lightness, and enduring weather, is generally preferred to any slate in Great-Britain."
The working of the quarry is described in 1758 as follows: "The whole quarry is about three hundred yards long and one hundred wide: the deepest part from the grass is judged to be forty fathoms. The masses are first raised rough from the rock by wedges driven by sledges of iron, and contain from five to ten, twelve or fourteen feet, superficial square of stone: as soon as this mass is freed by one man, another stone-cutter, with a strong wide chisel and mallet, is ready to cleave it to its proper thin-ness, which is usually about the eighth of an inch; the shivers irregular from two feet long, and one foot wide, downwards, to one foot square and sometimes (though seldom) dividing into such large flakes as to make tables and tomb-stones. In this quarry several parties of men work on separate stages or floors, some twelve fathom from the grass, some twenty, others forty fathom deep, according to the portion of ground belonging to each party; the small shattery stone, not fit for covering houses, serves to shore up the rubbish, to divide the different allotments, and shape the narrow paths up and down the quarry; all the slate is carried with no small danger from the plot where it rises, on men's backs, which are guarded from the weight by a kind of leathern apron, or rather cushion; the carrier disposes his charge of stones in rows side by side, till the area allotted to his partners is full, and then horses are ready to take them off, and carry them by tale to the person that buys them."
The working in 1882 had changed with the advent of the steam engine: "The scene is enlivened by a throng of men busily engaged in various noisy employments, while waggons and horses are everywhere in rapid motion, and steam-engines are lifting with a harsh sound their ponderous arms, and raising loaded trucks from the depths of the pit, or masses of slate of several tons' weight, which are seen slowly ascending guide-chains to stages which overhang the quarry. The quarry is about 260 ft. in depth. Upon the edge of the quarry is the Papete Head, a projecting platform, from which a number of guide-chains are stretched like the shrouds of a ship to the base of the pit. The slate is first loosened by small charges of gunpowder ; it is then torn up by wedges and crowbars, and placed in trucks, which, being attached to a wheel which traverses a guide-chain, are drawn up by the steam-engine some feet above the Papete Head, Movable stages, called hatches or tables, are then run out under the trucks, which, being lowered upon a framework on wheels, are drawn away by horses to the different workshops, where the slate is split into various sizes, according to the purpose it is intended to serve. The water is pumped from the quarry by water-wheels into an adit, and the slate is shipped at the little harbours of Port Gaverne, Port Isaac, and Boscastle, the former being the principal port in the summer, the latter in the winter, as affording the best shelter to the vessels. About 1000 men are employed in these works, who raise on an average 120 tons of slate per day." ("Papete" is thought to be a local abbreviation of "Parapet").
The huge pieces of slate winched from the quarry by steam engines were known as "steamers". Occasionally, a chunk would fall off one, back into the quarry, or a chain would snap and whip into the edge of the quarry, causing a rockfall. Landslips also occurred occasionally, due to faults in the rock above the face being quarried, or material on the edges of the pit collapsing. There were a number of injuries and fatalities but also some miraculous escapes. One quarrymen was saved by his pasty, which a cheeky raven grabbed and he gave chase, narrowly avoiding a landslip where he had been standing. Another quarrymen, ascending a ladder, was hit in the backside by a flying piece of slate and found himself sat, unhurt, on the grass at the side of the quarry pit!
Even in Victorian times, slate was blasted with black powder (aka gunpowder), rather than high explosives such as dynamite. This is because high explosives combust with a supersonic shockwave known as a detonation wave, travelling at a speed of more than a mile per second. This causes very high pressure and resulting high temperature in the explosive, setting off neighbouring parts. This would shatter the brittle slate into tiny pieces, rather than breaking off large chunks.
As fuse technology improved, holes were drilled at regular intervals along a quarry face, filled with black powder. These pockets were all blasted simultaneously using a linked fuse (electrically triggered in the latter years of quarrying), to break off a very large chunk of slate. You can sometimes see the blasting holes in waste pieces of slate on the slate tips.
The road from Port Gaverne which joins the Delabole road was quarried out in the early 1800s by the Delabole Slate company and known as "The Great Slate Road". Around 100 ships a year came to Port Gaverne to collect slate, each capable of carrying 50-80 tonnes. It would take thirty wagons, pulled by over a hundred horses, to load a sixty ton ship. The slates were loaded by women, who then packed them in straw to protect them on the voyage. The incoming ships also brought coal from Wales and limestone, for the local limekiln, which was used to whitewash the cottages.
The number of cows in Cornwall has been estimated at around 75,000 so there's a good chance of encountering some in grassy fields. If you are crossing fields in which there are cows:
The acidic soil in the Tintagel area was fertilised with lime-rich beach sand from nearby Trebarwith Strand, where the golden sand is largely composed of sea shells which are mostly calcium carbonate (chemically identical to chalk and limestone).
The sand at Trebarwith Strand was also put to another use: to avoid several tonnes of slate in a wagon going down the steep road through Trebarwith Valley resulting in horse paté, the slate wagons would be loaded with sand from Trebarwith Strand and this would be scattered on the road on the way back up, to act as a braking system.
The trade in sand and slate quarrying led to road improvements in the early 19th century and for one reason, or the other, or possibly both, the Trebarwith Strand to Condolden road is known as "Sanding Road".
The path ends in a platform which overlooks a waterfall, tumbling into the quarry pit. This is the stream that runs across Trewarmett Downs. When the quarry was being worked, the engine house pumped the water out of the pit, to prevent it flooding, and also powered slate-hauling equipment to lift the slate out of the pit.
The Prince of Wales quarry is in Trebarwith Valley, overlooking Trewarmett. The quarry opened in 1871 but was only worked for just over 20 years, closing 1890s; the slate quarried here was blue slate from the Upper Devonian Penpethy Beds. A circular path now leads through the old slate tips, past the quarry pit (now a lake with a small waterfall) and up to the engine house which has good views of the valley and coastline.
Cornwall's iconic engine houses were built to house huge beam engines - a type of steam engine with a pivoting beam. This configuration was particularly suited to powering pumps to stop the quarry pits and mines from flooding as water trickled into them from above. Inside the engine house, steam from a boiler would push up a piston, causing the beam to tilt downwards, pushing the pump down into the shaft. The steam would then be shut off and cold water would be used to condense the steam within the piston back into water, creating a partial vacuum. Atmospheric pressure then pushed the piston back down into the vacuum, raising the beam and lifting water out of the shaft. The valves to apply the steam and cold water were mechanically automated, maintaining a steady rocking motion of the giant beam.
The engine house in Trewarmett is the only one preserved in North Cornwall. It was built in 1870 and the beam engine, installed in 1871, was used to drive a wire ropeway to haul slate, as well as pumping water out the quarry pit (which is now a lake). You can safely wander around inside (there are grilles covering the pit which once contained the beam engine).
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