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Robert Plot

Notable Local Geologists: Robert Plot

Robert Plot (1640-1696)

Professor Michael Winterbottom tells the life story of a pioneering naturalist, chemist and first keeper of the Ashmolean.

Robert Plot (1640-96) holds an honoured place in the story of science at Oxford. But Oxford geologists remember him best for his book on the natural history of the county. This was first published in 1676. A second rather enlarged edition appeared in 1705. Both editions are available on line, and a serviceable reproduction of the later one can be obtained for a modest sum. 


Though he was born in Kent and passed his last years there and in London, Plot’s life was largely spent in Oxford; he was an undergraduate at Magdalen Hall (a part of the tangled history of the present Hertford College), and taught in various capacities until 1690. His was a glittering career, which brought him distinction at an early age. He was the first keeper of the Ashmolean Museum (founded 1683), then housed in Broad Street at what is now the Museum of the History of Science; and to this post was attached the first professorship of Chemistry in the university. Plot had already, in 1677, been made a fellow of the Royal Society (founded only in 1660). He was a Renaissance man of wide and various interests, and rubbed shoulders in Oxford with the likes of Robert Boyle. It is good to learn that this astonishingly hard-working man was ‘convivial, bibulous, a good companion, and jovial’. 

 ROBERT PLOT  (British Museum) 

“…whether the Stones we find in the Forms of Shell-fish, be Lapides sui generis, naturally produced by some extraordinary plastic virtue, latent in the Earth or Quarries where they are found? Or, whether they rather owe their Form and Figuration to the Shells of the Fishes they represent, brought to the places where they are now found by a Deluge, Earth-quake, or some other such means, and there being filled with Mud, Clay, and petrifying Juices, have in tract of time been turned into Stones, as we now find them, still retaining the same Shape in the whole, with the same Lineations, Sutures, Eminencies, Cavities, Orifices, Points, that they had whilst they were Shells?”

Robert Plot


The title page of the second edition of the Natural History of Oxfordshire says that it is ‘an Essay towards the Natural History of ENGLAND’. He clearly hoped to take the project much further. He remarks at one point: ‘whereof more at large when I come into Sommerset-shire’, and he did go on to write another volume, on very similar lines, about Staffordshire (1686). He was working on London and Middlesex in his last years. The scale of his conception of natural history is no less ambitious; there are ten chapters, taking us from ‘the Heavens and Air’ through Stones, Plants and ‘Brutes’ to Men and Women, Arts, and Antiquities. But it is naturally to chapters 3 ‘Of the Earths’, 4 ‘Of Stones’ and the very much longer 5 ‘Of Formed Stones’, that a geologist will turn.


It would be easy enough to make mock of what to us look like absurdities in Plot’s work. It will be more helpful here to stress some of the many points where he impresses a modern reader. Much information is taken from him in the standard accounts, W.J. Arkell’s The Geology of Oxford and (especially) Oxford Stone (both published in 1947), and our President’s The Geology of Oxfordshire (2005); indeed Philip Powell is the only man who could write what would make a fascinating book, a geological commentary on Plot’s three chapters.


Plot was up with the current literature. He often quotes, for example, from one of the founders of natural history, Ulisse Aldrovandi (d. 1606), whose great book, according to T.H. White, weighed in, counting all its volumes together, at 78 lb. 4 oz.: not to speak of ancients like the Elder Pliny. Then there were specimens to look at. At this period they were housed not in public museums (Plot was to leave his to the new Ashmolean) but in private collections, and the respectable Plot had an entrée to the great houses of the county. There was, for example, ‘the ingenious and observing Sir Thomas Pennyston, at his House at Cornwell’ (two miles or so west of Chipping Norton; we shall meet this man again), who found a fossil fish in a lump of coal, and showed Plot a ‘Bank of Yellowish Clay’ in his park, rich in ‘Cockle-stones’. Plot was indeed no armchair geologist. He was always on the move. He knew of ‘Ophiomorphits’ (‘snake-stones’) at Adderbury, but ‘though I were there often, I could meet with none of them’ (he could not resist warning the reader that the village was not named after these stones: in the court-rolls of New College he had seen it spelt ‘Eabberbury’). And he talked to people. Observing in various places a ‘fine Earth, of a White Colour, porous and friable’, he ‘enquired of the Quarry-men what it might be, whether they had made any Use, or Observations of it, but all I could get would amount to no more, but that it was a sign of a very good Lime-stone’. Farmers he asked about their soils were less obliging: ‘I found most of them Froward, and to slight my Queries.’

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Out in the fields it was the springtime of the world for the fossil-hunter. Plot says of the Cornu Ammonis (‘nothing else but the Petrified Shell of the Nautilus’) that it was common in Oxfordshire in different shapes and sizes. What he classified as ‘Brontiae’ or ‘Ombriae’ we call, after him, the Clypeus Ploti. It was, ‘at TangleyFulbrook, and all about Burford … found in such plenty, that I believe it were easy, in a little time, to procure a Cartload of the first sort of them, carefully exhibited in Tab. 2. Fig. 9, 10’. It is worth comparing these lovely engravings with the colour photograph in Powell’s book (p. 27). As well as these images, Plot took care to describe what he saw in detail: ‘all of them divided into five parts, most times inequal, rarely equal, by five Rays issuant from an Umbilicus or Center, descending from it down the sides of the Body, and terminating again somewhere in the Base.’ This is typical of his procedures: typical too that he notes that these fossils ‘are never found in Beds together, … nor … in great Numbers in one place’.


Plot was was well on his way


For Plot was well on the way to the stratigraphy that we associate with William Smith and his coevals a good deal later. He likes to record in what kind of rock a fossil was found: thus one ‘at Great-Rolwright in a Bluish Clay’. He speaks of ‘our Bed of Clay at Heddington, above the Quarry at some places ten Foot thick’. Most remarkable of all is his description of the ochre beds at Shotover, ‘on the East side of the Hill, on the Right-hand of the way leading from Oxford to Whately’: ‘The Vein dips [one of the earliest occurrences of the word in this sense] from the East to West, and lies from seven to thirty Feet in depth, and between two and seven Inches thick; enwrapped it is within ten folds of Earth, all which must be past through before they come at it; for the Earth is here, as at most other places, I think I may say of a bulbous Nature, several folds of divers Colours and Consistencies, still including one another, not unlike the several Coats of a Tulip Root, or Onyon.’ Plot distinguishes ten such layers: ‘1. Next the Turf, is a Reddish Earth. 2. A Pale Blue Clay. 3. A Yellow Sand. 4. A White Clay [used, he remarks later, ‘during the late Wars, in the Siege of Oxford, … for making Tobacco-pipes there’]’ through to ‘9. A Green Clay again. 10. Another Iron Rubble … And then the Yellow-Ochre, which is of two sorts …’. Nor does it stop there: ‘for within two Beds next under the Ochre (nothing but a white Sand interceding) there lies another of a much Redder Hue.’


Robert Plot was interested in absolutely everything, and he does not neglect the uses of his earths and stones. He tells us what had to be done to make ‘Clay-Ochre’ ‘fit for the Merchant’. He knows what was done with the ‘Flat-stone’ found at Stonesfield to produce a roofing material: ‘it is dug first in thick Cakes, about Michaelmass time, or before, to lie about all the Winter and receive the Frosts, which make it cleave in the Spring following into thinner Plates, which otherwise it would not do so kindly.’ And he tells us of the stone used for building Oxford colleges. Wheatley stone was popular, ‘yet it endures not the Weather so well as Heddington, by reason, I suppose, of a Salt it has in it [‘all Stones are chiefly made out of Salts, with a Mixture of Earth, and sometimes of Sulphur’], which the Weather in time plainly dissolves, as may be seen by the Pinnacles of New-College Chappel, made of this Stone, and thus melted away.’

[ ‘all Stones are chiefly made out of Salts, with a Mixture of Earth, and sometimes of Sulphur’], which Weather in time plainly dissolves, as may be seen by the Pinnacles of New-College Chappel, made of this Stone, and thus melted away.'

Extract from Plot letter (Oxford: Sept. 16, 1682)



So that I shall trouble you no further at present but that you would let me know by your next, whether you ever heard of any such mineral stone as Black Daze, and what it is: I have met also with another sort of mineral called Caule, whereof there are two or three sorts, but I cannot find what it should be, whence it should come, or its uses. If you know any thing of them pray oblige


                                    Dear Sir

                        Your most faithfull Friend and humble Servant Robert Plot



We thank our friends at the The Bodleian Libraries, The University of Oxford

Shelfmark: MS. Lister 35, fol. 75r.

Plot the geologist, though, is best known for something of no use whatever, and something he quite misinterpreted. The object in question was ‘dug out of a Quarry in the Parish of Cornwell, and given me by the Ingenious Sir Thomas Pennyston.’ It had ‘exactly the Figure of the lowermost part of the Thigh-Bone of a Man, or at least of some other Animal’. But it was two feet long and weighed almost twenty pounds. Plot was clear that it was not the result of natural processes within the rock, but ‘must have been a real Bone, now Petrified’. But from what beast? Ox and horse were too small, so perhaps elephant. But with much learning Plot shows that elephants were not seen in England before 1255; and, if two or three had been imported ‘for Show’ since then, ‘whether it be likely any of these should be buried at Cornwell, let the Reader judge’. Then, in 1676, ‘there happily came to Oxford while I was writing of this, a living Elephant’. Even though it was not full grown, Plot found that it was built on a much bigger scale than the owner of his thigh-bone. That, then, could only come from a man or woman; and with further show of learning Plot demonstrates that ‘there have been Men and Women of proportionable Stature in all Ages of the World, down even to our own Days’ (though he does not back up this last point).


That is where he leaves his bone. Only in the nineteenth century was it to become clear that what he had seen was a relic of that peculiarly Oxfordshire creature, the Megalosaurus. Fragments of the animal were collected and described by another of our local heroes, William Buckland, and are now on display in the Oxford University Museum of Natural History. What became of Plot’s thigh-bone is not known.


‘I cannot but reprehend the petulant Despisers of this innocent sort of Learning, who in Derision have called it, picking of Stones.’


Plot starts his fifth chapter, on natural ‘stones’, with a spirited defence of his interest in such things. ‘I cannot but reprehend the petulant Despisers of this innocent sort of Learning, who in Derision have called it, picking of Stones.’ For Plot, they ‘seem rather to be made for [man’s] Admiration than Use. Whereof the World is beautified with so great Variety, that as on the one Hand, I cannot but wonder at the great Providence of God, and his most perfect Workmanship, that has thus created the Universe for Man’s Delight as well as Use.’ There is room for a study of rocks as objects of aesthetic interest, painted by John Ruskin and photographed by those who compete for the Oxford Geology Group H.C.H. Crawley Cup.

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