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CROWNS ROCK AND ENGINE AT BOTALLACK MINE

A 19th Century engraving on the right of Crowns Rock and a steaming engine house at Botallack Mine, St. Just, Penwith. This is a notoriously dangerous coastline showing the mast of a wreck.  You can see men fishing off the rocks and a Bal Maiden (woman mine labourer) carrying a jousters flasket or a cowl on the long climb back to home.

The photograph below is taken about the same time of the incoming tides and shows the two engine houses of Botallack Mine close to the sea.

The view looks south westwards along the top ridge of magnificent cliffs with two engine houses the nearest being Wheal Owles and the further one is Wheal Edward on the coastal path.

Botallack Mine

The Botallack set includes the names of Wheal Cock, Crowns, Carnyorth, Botallack and Parknoweth and there are many small shafts and workings such as Wheal Bal, Wheal Hen, Wheal Tolvan, Wheal Button and Wheal Hazard.  It is known that the lodes were exploited since at least 1721.The submarine levels at Wheal Cock were being worked in 1778 when Pryce described how the miners were frightened by the rumbling of the rocks on the sea bed above their workings during  storms.Joseph Carne stated that in 1822 that it had been wrought under the sea beyond the memory of any person now living.                 

The lower Engine House nearest to the sea was the Pumping Engine House and the higher one the Winding Engine House.These are both known as the Crowns Engine Houses and the Crowns Mine  as they sit on the Crowns Rock.The lower Pumping Engine House was was built in 1835 to pump water from the mine.The higher Winding Engine House was built in 1862 to provide winding power for the Boscawen Diagonal Shaft which ran down the zawn and under the sea.

Work sinking the Boscawen Diagonal Shaft began in 1858 and provided access to the seaward lodes one third of mile under the sea.und up and down by the Steam Engine.A terrible accident occurred in 1867 when the gig chain broke and eight miners and a boy went crashing to their deaths.

The chimney on top of the cliff headland (well behind the upper winding engine house to its right in the picture) is a chimney stack of the arsenic labyrinth. The crushed ore would have been roasted in a nearby oven called a Calciner.This would have caused a sulphurous arsenic gas which was sucked along the underground flues and arched chambered labyrinths by drafts from the chimney which then discharged out of the stack and the gases in the chambers would have condensed and left white crystals of arsenic on the walls where they were gathered up.

Higher up on the site there are dressing floors dated 1860 and 1906, the smithy and the Count House, (the mine's accounts House)  provides a fascinating look at Cornish mining over a century ago. Here concrete plinths and dressing floors on the site of the mill used to process tin ore. That of 1906 was the last used in reworking the ores with large heads of stamps crushing the ores to sand sized grains and also various methods used to extract the tin using water and gravity.

A Brunton Calciner was used for the extraction of arsenic during the 1906-1914 period just before the First World War.

Geology and Minerals                                                                                                                                                                      Most of the Western Peninsula is composed of granite, a coarsely crystalline plutonic igneous rock formed deep down in the earth's crust about 280 million years ago. These granite magmas from below, intruded and were pressurised into existing older rocks which were metamorphosed or cooked and were changed into dark coloured slates (from rocks which were previously sedimentary shales and mudstones known to the Cornish as Killas) and volcanic rocks that were changed into Greenstones and Hornfelses.

Within both the granites and the metamorphosed older, nearly vertical faults and voids; these became infilled with migrating gases and hot fluids rich in tin and copper and other metals which later cooled and coated their walls to become vertical lodes of tin and copper rich ores.  These are now formed at right angles and have travelled through the rocks from the hot centres in the magma along great lengths and heights. These lodes penetrated the rocks from the granites and out in the bedrocks now under the sea.  The Cornish miner's were famous for their skills and techniques in pursuing these lodes underground and under the sea.

The mines of Levant and Botallack were amongst the famous names of these submarine mines. The lodes were nearly vertical dipping between 70-80 degrees and as narrow as 1 metre but as long as a mile in length and longer.

The world price of tin is notorious for variation and at one time Geevor speculated with renewed interest taking on the Botallack Sett to exploit the submarine.  They again constructed the Allen's Shaft and Head Frame still visible near the Count House. However, the price of tin dipped again following this and the Allen's Shaft was abandoned and was left as you see it today.

Another fact to highlight is that the granite magmas and lodes in question, placed 280 million years ago, penetrated the older rocks from the hot granite magmas in the earth's crust to levels which continued to be uplifted but still great distances below the then existing surface and it is only due to several 100's of millions of years of erosion since then that we can now walk on these exposed land levels which have become the Cornwall that we know.

Similarly the levels of the present day sea bed may have equally been as high as present day Cornwall. There were several 100 millions years of  marine erosion and of course this would have also included the many recent Glaciations and Interglacial periods where aerial erosion was severe and important and sea levels changes and land level changes would have be so different than they are today!

Erosion of those areas and complete removal of the crust of the previous land areas to the north of the existing coastline, and the continued submarine erosion of primary lodes still existing and coming to the surfaces under the sea, would have released heavy metals which may have been concentrated within the  sea floor sediments. On land of course the small Cornish rivers and the more substantial erosion of the periglacial times would have created the alluvial tin beds which early inhabitants would have been all to aware of. Continuous cliff falls would also have provided the sea with new  primary ores to sort and shift into beds of sediment on the sea floor rich in sands and rocks and concentrations of heavy ore minerals such as tin.

Well worth seeing!                                                            

There is a rather interesting exhibit within the Botallack Count House that illustrates the enterprise of alluvial mining, exploiting the tin within the valleys of Penwith around Botallack and St.Just.  This was created both by the natural erosion and supplemented by the mine waste of a few 100 years of Cornish Mining.   Most 19th-century mines had account houses, or 'count houses' to provide office space for the purser and his managerial staff. They were generally grander than other local buildings. As the public face of mining, they had to look refined as well as solid and prosperous in order to reassure investors and the world at large. A count house was principally the office from which the mine was run on a day-to-day basis; here the miners were paid and the rights to work or 'pitches' within the mine were auctioned on 'setting days'.

The Counts House of Botallack is a good meeting place especially if you need a little shelter, but it also provides a small but interesting exhibition and the National Trust provide leaflets and literature.    
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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