Category Archives: Beagle

Darwin’s first attempt at geology – Llanymynech

After leaving Cambridge in early 1831 Charles Darwin returned to his home – The Mount – in Shrewsbury

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and decided to learn some geology in preparation for a trip to Tenerife, which never came off. At that time geology was not well-developed and all the strata belowed the Carboniferous (U.S.A Mississippian) was unknown. Sedgwick and Muchison began to unravel later that year, with Darwin in tow with Sedgwick.

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a superb presentation of the Geological Column by Ray Troll, accurate and witty.

By early July Darwin had obtained his geological equipment and was especially proud of his compass-cum-clinometer. Here is his actual field bag and actual equipment, which is stuill the basis for field work today.

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He also needed maps and he used Robert Baugh’s topographic map of Shropshire (wait for my next blog) and Greenough’s geological map of England and Wales. This is a photo of Darwin’s actual copy in Cambridge Univ Library.

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After leanig how to use his clinometer on furniture he went into the filed to try his hand at field work. His destination was Llanymynech Hill some 15 miles west of Shrewsbury. I presume he travelled on one of the horses. His notes, transcribed below say NE, but that is typical of Darwin’s compass inversion, which he did both at Llanymynech and Cwm Idwal. If you don’t visit the sites and sit in stuffy libraries just reading his notes you’d never see this. You cannot do the history of geology without fieldwork, getting soaked, chased by irate cows and twisting ankles.

TRANSCRIPTION OF THE LLANYMYNECH NOTES,g
Llanymynech 16 miles NE [sic] of Shrewsbury; to the north of the village about ] of mile in an extensive quarry of Limestone. On the road to it, passed over a hillock of a soft slaty rock. some of the Strata were crumblingaway by exposure to the air. Strata very distinctly defined inclined at 78″. Direction ESE 6a 1i7N!7. The quarry is worked in the escarpment of a range of Carboniferous Limestone facing S by ]if. On the Eastern side & high in the hill where the stratification is better marked the rock more compact & of a redder colour. the seneral D is NE b N 14′. To the Westward & lower down D of st.ata is more NW 6< the angle lessl In centre there of quarry are several great cracks passing strait thrugh the rock now filled with clay. To this line the strata on each side are inclined on each side from [E crossed out] tOf 10″ & from [W crossed out] E 15o. It gives to the strata the appearance ofcurves. The stratification of the whole Western side appears to be less regular than that of the East. At one place I observed a series of strata having D ENE 10″ – The lowest Strata of Limestone that are worked consist of rocks of a softer texture, marked in patches by a brightish red, called by the’Workmen’bloody veined’Beneath there is the Delve consisting of avery argillaceous Limestone, soft & wastingaway on exposure to the air. it is not worth being burnt for Lime – The Workmen have never gone beneath this.

This has recently been put on the extensive website Darwin on line 

http://darwin-online.org.uk/content/frameset?pageseq=1&itemID=CUL-DAR5.B1-B4&viewtype=side

Llanymynech Hill bounds the west of the Shropshire plain and his an extensively quarried limestone hill of 226 metres. The carboniferous limes lies on top of silurian slate (hill of slaty rock) There is a golf course on top for those who like to spoil a good walk and ther is a heitage trail. It is a hill I know very well as I have walked all over it and also done several of the rock climbs. On the visit I made all my measuresments i’d cycled the 11 miles from Chirk.

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View looking ovber Breiden Hills

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viewpoint with details for trail and on Darwin

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Information board gleaned from my work

From Darwin’s notes it seems he came up from Llanymynech village and truned off on a lane at the bend GR266212.

The exposures are at the bend just up the hill. Continuing up you see the quarry cliffs and then need to find the paths onto them.

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As you go up the lane you find the “slaty rock” with some obvious bedding. That was infuriating to measure as I found they dipped to the NW. It seems he was dyslexic  – like the best of us. The strata were later seen to be Silurian.

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Following up from those slaty rocks a path leads you into a quarry. This not as Darwin saw it as further quarrying took place for about a century.  It is now abandoned and a  haven for wild flowers and rock climbing. Some of the hardest routes are here, which I had to second rather than lead.

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The limestne is well-stratified, with some interspersed muddy beds. Worsely is valuable on this. (The mud made for hairy rock-climbing in the rain.)

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To read more, open up for my paper in the Brit Jour of the History of Science

Darwin at Llanymynech

Peter Worsley has corrected some of my conclusions on the mudcracks!

http://www.emgs.org.uk/files/publications/19(3)_contents.pdf

Darwin was baffled by the Bellstone in Shrewsbury, but in 1831 nop one knew that it had trundled down from Scotland on an ice sheet

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After his next work on maps (my next blog) Adam Sedgwick arrived on the scene at the Mount. Big sis Susan took a shine to the reverend geological bachelor and his sister Caroline wrote to Darwin on the Beagle to say they expected Susan to become Mrs Sedgwick!! That would have been fun for historians.

So in August Sedgwick arrived and took Charles around North Wales in a gig and taught him a litte geology 

https://michaelroberts4004.wordpress.com/2020/07/03/just-before-the-beagle-darwin-in-wales-1831/

 

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Just before the Beagle, Darwin in Wales, 1831

1831 was an eventful year for Charles Darwin. In the first half of the year he graduated from Cambridge with an adequate degree. He had plans for the future; first an expedition to Teneriffe and then a life as a clergyman, when he’d have time for plenty of natural history. Had this happened he would have been one of the last of people without much Christian conviction to be ordained. Even Darwin noticed that clergy were more devout when he returned from the Beagle voyage in 1835.

Many make much of the fact that his degree was in theology and philosophy rather than science. But then you couldn’t do a degree in science, but Darwin did the next best thing, or was it the best thing. For much of his time at Cambridge he attached himself to Rev John Henslow, who was then prfessor of Botany. He had been professor of mineralogy and in the early 1820s produced memoirs on the geology of the Isle of Man and Anglesey. Have been round Anglesey with Henslow’s map and memoir I found found it an incredible piece of geology.

The second half of the year was so different. He had returned to Shrewsbury and tried to teach himself geology with limited success. For the most of August he was in North Wales with Adam Sedgwick as be begand his pioneering work on the Cambrian. After trekking from Capel Curig to Barmouth, he went home to find a letter inviting him on the Beagle.  He managed to get his uncle – a Wedgwood – to persiade his father  and on 27th December set sail from Plymouth.

Things were never the same again.

As you read this you will see how well qualified Darwin was to go on the Beagle. He was already recognised as one of the best of the young naturalists.

For the future Dawin the scientist, or rather Darwin the geologist, July and August were the most crucial. During July he tried to carry on the geology he’d learnt from Henslow and Sedgwick with limited success. He visted Llanymynech quarry and tried to produced a geological map of his home ares.

Then Sedgwick arrived in early August to stay at the Mount. From there Darwin joined Sedgwick on two day trips from Shrewsbury and on 6th August the set of for Llangollen in Sedgwick’s gig. Sedgwick was trying to work out the strata below the Old Red Sandstone (Devonian) and thus gradually sorting it out going down the succession. Ironically he got within 2 miles of this on Long Mountain near Shrewsbury, but turned back – possibly because the horse was knackered! It is a long pull-up and one many cyclists today would avoind or regard it as a hard climb.

As there is no Devonian in North Wales from Llangollen to the Great Orme, Sedgwick got nowhere, beyond teaching Darwin geology. A trip to Anglesey didn’t help and so Darwin left him to travel home to go shooting. As it was Sedgwick started to work around Llanberis and he had not stratigraphic markers to work on. But that is another story.

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To go back to early July, Darwin received a parcel of a clinometer, and hammer and so started measuring angles all round the house. To test out his skills he rode the 15 miles to Llanymynech Hill,

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which I describe in this paper along with Cwm Idwal

Darwin at Llanymynech

Darwin at Llanym

Also that July he took some local maps of Shropshire by John Baugh, traced then tried to make a geological map.

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Both south of Shrewsbury and at Ness he found New Red Sandstone – Permotrias.

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I ..coloured a map 

A paper on Darwin’s attempts of geological mapping around Shrewsbury, published in Archives of natural History  1999

Coloured a map

These are two papers one co-authored with Sandra Herbert.

and so we come to the main partof his geological journeys, this time with Sedgwick.

On 2nd August 1831 Sedgwick arrived at the mount in his gig. Dr Darwin thought him a hypochondriac. The next two days were spent looking for Old Red sandstone to the east of Shrewsbury and on the 6th Sedgwick and Darwin set off to north wales as described in this paper published in Endeavour in 2000.

Open and read

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Darwin wanted to get home for some shooting and left Sedgwick near Bangor.After Darwin left Sedgwick he went to Cwm Idwal ,

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And Sedgwick’s sketch of Devil’s Kitchen drawn a few weeks later.

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then onto Plas y Brenin at Capel Curig, climbed Moel siabod and walked south to Barmouth

Darwin’s route as a mountain expedition, written for a mountain magazine

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And now more scholarly!!

Darwin never took a compass bearing from Capel Curig to Barmouth. I don’t recommend you try it!! It would cross incredibly rough pathless ground. However I am willing to follow anyone who wishes to try it – especially if they are not used to british hills.  My sadism is coming out here.

As it was he went in a roundabout route and you can visit the localities he described.

Darwin’s Dogleg

This from Archives of Natural History describes the route Darwin took from Capel Curig to Barmouth

Darwin’s dog-leg

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And so after a few days with his mates he went home and found the famous letter!

Six months later he carried out his first geology on the voyage at Cape Verde and here I refer to Paul Pearson.

‘Marks of extreme violence’: Charles Darwin’s geological observations at St Jago (São Tiago), Cape Verde islands

P. N. Pearson and C. J. Nicholas

Abstract

The first stop on Charles Darwin’s famous voyage around the world in HMS Beagle was at Porto Praya (Praia), the principal town on the island of St Jago (São Tiago) in the Cape Verde archipelago. From 16 January to 8 February 1832, Darwin enjoyed his first substantive opportunity to study the natural history of an exotic place. Darwin himself regarded this occasion as a significant turning point in his life because, according to his autobiography, it was here that he decided to research and publish a book on the geology of the places visited on the voyage. He also recalled that it was here, the very first port call, that convinced him of the ‘wonderful superiority’ of Charles Lyell’s uniformitarian geology over the doctrine of successive cataclysms that he had been taught in England. Later commentators have generally accepted this account, which is significant for understanding the intellectual background to the Origin of Species, at face value. In this paper we reconstruct some of Darwin’s observations at St Jago based on his contemporaneous notes and diary, and in the light of our own visit made in January 2002. We find little evidence to substantiate the claim that he interpreted the geology in Lyellian terms at the time. Instead, he formulated a theory involving a great cataclysm to explain the dramatic scenery in the island’s interior. He speculated that a torrent of water had carved the main valleys of the island, leaving deposits of diluvium in their beds. It is indisputable that Darwin came to embrace gradualist thinking enthusiastically during the voyage. Some of his observations made on St Jago, especially relating to uplift of the coast, were instrumental in this change of view, but the conversion was gradual, not sudden. His later published works make no mention of his original catastrophist interpretations.

https://sp.lyellcollection.org/content/287/1/239/tab-figures-data

And so Darwin went round the world studying the geology.

His last geological trip was to look for glaciation in Shropshire and Wales culminating in Snowdonia in 1842 as this paper on William buckland in 1841 and Darwin in 1842 shows.

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