Darwin’s Beagle notebooks are heavily weighted with his geological observations. As he travelled he collected rocks and fossils; he packed an immense box of bones, shells and fossils and sent even larger boxes back to John Henslow in Cambridge. Much has been made in recent years of Darwin’s observations on the varied species of finches and mocking birds on the Galápagos Islands. Less noticed is the fact that his notebooks contain more about rocks than about living creatures. The half dozen large islands, which lie on the Equator, are volcanic in origin and Darwin wanted ‘a good look at an active Volcano’, as he told Henslow.6 In fact, he saw a great many and walked to the tops whenever possible.
The Beagle notebooks also contain what is only now being brought to public attention: Darwin’s hatred of slavery. Coming from an abolitionist background (both his grandfathers, Erasmus Darwin and Josiah Wedgwood, were outspoken campaigners against slavery), Darwin was horrified in Brazil to see that the practice was even crueller than he had imagined: ‘Every individual who has the glory of having exerted himself on the subject of slavery may rely on it [that] his labours are exerted against miseries perhaps even greater than he imagines.’7
Towards the end of its voyage, in April 1835, the Beagle sailed northwards along the coast of Chile. There Darwin saw the famed terraces of Coquimbo – flat parallel trails in the mountains high up over the port city. He took the sight as evidence of the recent emergence of the whole of the Chilean coastline and concluded that the elevation of the Andes was still continuing. It was while in Chile that he first experienced an earthquake. It shattered his sense of reality. ‘The world, the very emblem of all that is solid,’ as he later wrote, shuddered beneath his feet ‘like a crust over a fluid’.8
Back from the Beagle – his home for nearly five years, from December 1831 to October 1836 – Darwin realised his true vocation was to be a geologist. He was immediately admitted to the Geological Society and was henceforth entitled to style himself ‘FGS’, although he thought it ‘a great pity that these and the other letters, especially F.R.S. [Fellow of the Royal Society] are so very expensive’. Admission cost him six guineas and an annual three guineas. Yet his worth was appreciated; he would be on the society’s council for the next thirteen years.
He met Charles Lyell, who suggested that Darwin might also like to apply to join the new Athenaeum Club: ‘if you like to dine at the club do so. There is no vacancy, but you stand the first of those who are knocking at the door for admission.’9 The club had been founded in 1824 by the then president of the Royal Society, Sir Humphry Davy, and the Tory politician John Wilson Croker, and was intended for literary, scientific and artistic gentlemen. It quickly acquired 900 members and Michael Faraday was its first secretary. Unusually for the time, the club did admit ladies, if only on Wednesday evenings. Some members grumbled at the invasion, Lyell observed in a letter to his sister: ‘retreated into the library, which was respected at first, but now the women fill it every Wednesday evening, as well as the newspaper room, and seem to me to examine every corner with something of the curiosity with which we should like to pry into a harem. They all say it is too good for bachelors, and makes married men keep away from home.’10
After meeting Lyell in person, Darwin felt enormous admiration for him and they became fast friends. He wrote to his brother on 6 November 1836: ‘Amongst the great scientific men, no one has been nearly so friendly and kind, as Lyell.’11
Lyell shared the appreciation for friendship; he told Darwin: ‘I have spent the last week entirely in comparing recent shells with fossil Eocene species, identified by Deshayes. When some great principle is at stake, all the dryness of minute specific comparisons vanishes, but I heartily long for some one here with a collection of shells, and leisure to talk on these matters with.’12 He advised Darwin: ‘Don’t accept any official scientific place, if you can avoid it, and tell no one that I gave you this advice, as they would all cry out against me as the preacher of anti-patriotic principles. I fought against the calamity of being President as long as I could.’13
At this time the accumulating fossil record was making the changes of species during the geological past the central question in geology. By March 1837 Darwin had concluded that species were not immutable; he opened his first notebook on the subject in the following month.
Two years later, in June 1838 – at the age of twenty-nine, unbearded and not yet married – Darwin took himself up to Scotland to see for himself the great geological conundrum of the Highlands, the so-called ‘Parallel Roads of Glen Roy’. He was well aware that he knew little about British rocks.
His motives were not entirely geological. Overworked by writing his Beagle notebooks, he needed to get some fresh air for his health. He had promised his intended bride – his cousin Emma Wedgwood – that he would finish the Glen Roy paper and then they would marry.
Darwin had addressed the issue of marriage before he left for Scotland. Ought he to remain a bachelor? He posed the question to himself on a scrap of blue paper, drawing up two columns, one headed ‘Not to Marry’, the other ‘Marry’. On the ‘Not Marry’ side, he set thirteen advantages such as ‘Freedom to go where one liked – choice of Society & little of it. Conversation of clever men at clubs – Not forced to visit relatives, & to bed in any trifle. – to have the expense & anxiety of children – perhaps quarrelling. – Loss of time. – cannot read in the evenings – fatness & idleness – . . . if many children forced to gain one’s bread’ and ‘Travel. Europe, yes? America????’ Against these, in the ‘Marry’ column, he set ten advantages such as ‘Children (if it please God)’ and ‘a nice soft wife on a sofa with good fire, & books & music perhaps’. It was no choice. He concluded emphatically: ‘Marry – Mary [sic] – Marry Q.E.D.’14
On 23 June 1838 Darwin took a steamboat to Edinburgh and arrived five days before Victoria – who had just turned eighteen – was crowned queen. He walked round the city where he had briefly attended medical school. Next he made his way to Fort William on the west coast, then headed north, passing the distant snow-capped mountain of Ben Nevis until he reached the Lochaber region and the town of Spean (pronounced ‘Spee-an’) Bridge. After a night’s sleep, he entered the nearby valley of Glen Roy. At once he saw the puzzling natural configuration that he had come to explain (and which remains to be seen, in the same form, today).
The first written account of the parallel roads appeared in 1776, in the appendix to the third volume of a guidebook by Thomas Pennant called A Tour of Scotland: ‘In the face of these hills, both sides of the glen, there are three roads at small distances from each other and directly opposite on each side . . . They are carried along the sides of the glen with the utmost regularity, nearly as exact as drawn with a line of rule and compass.’15 Indeed, along both sides of the wide and beautiful glen run three horizontal parallel terraces – the so-called ‘roads’ – as flat as if they had been levelled by a giant grass roller. Not only flat but wide – sixty feet across. The lower shelf lies 200 feet below the middle, the topmost 100 feet above that. The valley itself encompassing these roads is triangular. Narrow at the northeastern end, at the southwestern end it is open wide. One obvious explanation to Darwin was that the shelves were remnants of a former lake. But if so, what had held the waters in? The answer, Darwin decided, was that the valley had not held a lake; it had been an inlet of the sea and the waters had risen and subsided as the sea level changed.
Darwin’s hunch followed Lyell’s own. In the fifth edition of Principles (the fourth edition of 2,000 copies having been nearly all sold in one year), Lyell had called the Glen Roy shelves marine beaches.16 Darwin himself could hardly forget that a year before he had seen similar parallel terraces in Chile. Where the terraces were littered with seashells he had swiftly concluded that the roads were beaches of the Pacific Ocean, their parallelism showing him that the earth had risen at three distinct times. He drew detailed diagrams of the sight in his notebooks.
This dramatic and distant phenomenon was just the
subject Darwin wanted for his debut at the Geological Society. When the occasion arrived, he delivered a paper on his proofs of the ‘recent elevation of the coast of Chile’. No intelligent person, he said, could doubt the rise of the land or the falling of the sea. Since he, probably alone of their number, had actually seen Chile with his own eyes, no one contradicted him. How could Glen Roy be anything but the same? After eight days in the Scottish valley, Darwin was convinced that he was seeing the same phenomenon as he had observed in Chile. The shelves were old sea beaches that had risen as the land was lifted in stages above sea level.
However, there was one important difference. On the shelves of Glen Roy there were neither seashells nor barnacles. Their profusion had struck him at Coquimbo, where he interpreted them to have been deposited as the mountains rose in a series of stages from the sea. Darwin was not going to let that small detail bother him. He wrote to Lyell on 9 August 1838 how he had enjoyed ‘five days of the most beautiful weather, with gorgeous sunsets & all nature looking as happy as I felt’. He was fully convinced ‘(after some doubting at first) that the shelves are sea-beaches, although I could not find a trace of a shell’. He thought he could ‘explain away most, if not all of the difficulties’.
Returning home to Shrewsbury that summer and then shifting back to London, Darwin finished his paper on 6 September. ‘Eight good days in Glen Roy’ he put in his notebook. ‘My Scotch expedition answered brilliantly.’ He then began reading Thomas Malthus’s Essay on the Principle of Population (first published forty years earlier), noting that: ‘In October, 1838, that is, fifteen months after I had begun my systematic enquiry, I happened to read for amusement Malthus on Population. Here, then, I had at last got a theory by which to work.’17 Malthus held that human beings would continue to increase until they surpassed the amount of food available to feed them and that the poorer would always lose out to the richer in the struggle for food. In other words, the population was increasing geometrically while the food supply increased arithmetically.
It was not just from an intellectual interest in population. His father, Robert Darwin, a doctor, had warned Charles that he should marry soon if he wanted healthy children. Darwin himself was drawn to what Malthus called the ‘fruitfulness of marriage’ and would soon himself provide a notable example.
The day after he became engaged in November 1838, Darwin confided in Lyell that he felt ‘the most sincere love and hearty gratitude to her [Emma] for accepting such a one as myself . . . I hardly expected such good fortune would turn up for me’. He also told Lyell: ‘I deeply feel your kindness and friendship towards me, which in truth, I may say has been one chief source of happiness to me ever since my return to England.’18
He did not spell out for Lyell, a religious man, how strongly he and Emma differed on Christianity, however. Emma had written to him upon their engagement to thank him for his openness in telling her his anti-religious opinions, ‘but my own dear Charley we now do belong to each other & I cannot help but be open with you’.19 Nourished by the hope of an afterlife, she feared that her Charley endangered his chances by ‘casting off’ what Jesus had done for his benefit and for the whole world.
In December 1838, Darwin sent the completed Glen Roy manuscript – nearly ninety handwritten pages – to Lyell who, as a fellow of the Royal Society, forwarded it with a covering letter to one of the official secretaries. Darwin hoped they would not ask him to shorten it because, he said, there was not a sentence he could leave out. His Glen Roy paper, however, was not read to members until the next month, and then only by the society’s secretary who delivered it in three mumbled instalments.
Before its publication, Sedgwick read the paper and asked for a drastic shortening. Darwin refused and the paper went forward to publication in full. It ended: ‘The conclusion is inevitable, that no hypothesis founded on the supposed existence of a sheet of water confined by barriers, that is, a lake, can be admitted as solving the problematical origin of the “parallel roads of Lochaber”.’
It was Darwin’s first significant scientific paper and secured his election as a fellow of the Royal Society later that month (on 24 January 1839). Not for another eight years did the Royal Society change its rules so that new members would be elected on the basis of their contribution to science rather than for their social position or wealth. (This reform, long overdue, was introduced by Lyell’s Scottish geologist father-in-law, Leonard Horner, in 1846.20) But Darwin qualified on his own merits. He also paid £70 for the privilege. In choosing the senior institution to hear his Glen Roy paper, he had cold-shouldered the younger Geological Society. Five days after his election he married.
Darwin’s own work now moved to the study of species and their formation. He paid little attention the following year to the theory of the naturalist Louis Agassiz, who produced the later incontrovertible argument that the roads of Glen Roy (and much of the landscape of Europe and North America) had been formed by glaciers and not by the action of the sea and crustal elevation, as Darwin had maintained.
Long after, in 1856, Darwin received the Geological Society’s highest honour, the Wollaston Medal, for his outstanding contributions to geology. These were identified as three books drawn from his Beagle voyage: The Structure and Distribution of Coral Reefs (1842), Volcanic Islands (1844) and Geological Observations on South America (1846). His Glen Roy paper was not mentioned. Not until 1861 – two years after the publication of his world-shaking On the Origin of Species – did the young Scottish geologist Thomas Jamieson publish a more explicit and detailed reconstruction of how the glacial flow of ice had dammed lakes, thus creating the Parallel Roads of Glen Roy.
Darwin had to concede that his Glen Roy paper was wrong, telling Lyell: ‘I am smashed to atoms about Glen Roy.’21 Courteously, he wrote to Jamieson: ‘Your arguments seem to me conclusive. I give up the ghost.’22 He asked permission to forward the letter to Sir C. Lyell. (Darwin himself was never knighted.) But his Glen Roy error scarcely mattered. By then his name would never again be associated with rocks.
13
THE ICEMAN COMETH
In its third decade, the Geological Society of London met for dinner at the Crown & Anchor Tavern in the Strand before adjourning to the society’s rooms in Somerset House. While members were dining on the evening of 7 June 1840, a little over a mile away an attempt was made to assassinate the young Queen Victoria and her new husband Prince Albert as they were being driven up Constitution Hill. As the diary of a GeolSoc member records: ‘the news spread rapidly and naturally created a deep sensation’. The culprit was later declared insane and transported to Australia. The royal couple had been married only a few months.
For geologists, a more memorable event occurred three days later. The Swiss geologist Louis Agassiz read a paper titled: ‘On the polished and striated surfaces of the rocks which form the beds of glaciers in the Alps’. In it Agassiz, of the University of Neuchâtel, offered the then-unimagined idea that much of Europe’s northern half had once been covered by a vast sheet of ice, as indeed had much of the northern hemisphere.
The glacial hypothesis offered an explanation for the long scratches visible on the surface of many rocks. It also gave the first convincing answer to the mystery presented by huge boulders lying on utterly different kinds of rock – granite on limestone, for example – which showed that they were far from their place of origin. These conspicuous misfits were known to geologists as ‘erratics’ (or, to borrow a phrase from James Joyce’s as-yet-unwritten Ulysses, ‘Wandering Rocks’). Lyell, in the first edition of Principles, had suggested that drifting icebergs had carried the erratics around the landscape.
Three years before his London appearance, in an address to the Swiss Society of Natural History at Neuchâtel, Agassiz had announced the Eiszeit (Ice Age). He spelled out his discovery that, in the relatively recent past (that is, the Pleistocene era – a term later coined by Lyell), a massive glacier had covered Switzerland and central Europe, reaching the borders of the Me
diterranean and Caspian Seas. He attributed his awakening to the observations made in 1760 by the first scientific explorer of the Alps, Horace-Bénédict de Saussure. De Saussure had pointed out that miles below the snouts, or front edges, of the glaciers, the rock surfaces were scratched and smoothed, in striking contrast to the frost-splintered peaks above. He concluded that the glaciers had formerly extended many miles beyond their present limits and were retreating. Agassiz agreed with de Saussure; from 1837 to 1845 he had spent every summer but one in the Swiss Alps observing the movement of glaciers. He even had a hut built on one glacier so that he could keep a close watch on it. In 1840 he published his Etudes sur les glaciers.
From that day the Eiszeit theory was associated with Agassiz’s name. The concept usefully removed a global flood from geological speculation. It also brought Agassiz, between 1836 and 1840, grants totalling £240 from the Geological Society of London and the British Association for the Advancement of Science.
In November 1840 Agassiz came in person to deliver his theory of the recent Ice Age to the Geological Society. A handsome young man with a confident smile, he described glaciers as having existed not only in Switzerland, where they were yearly seen by thousands of foreign visitors, but in Ireland, northern England and Scotland. In his paper titled ‘On Glaciers, and the evidence of their having once existed in Scotland, Ireland, and England’, he suggested that glaciers had once extended much further than they did at the present day and had been the primary agents in gouging out the huge U-shaped valleys in Switzerland. These moving rivers of ice scratched the rocks as they slid over, carrying and dumping erratics which slipped down the slopes as the mountains rose. They also threw off debris on either side, forming ridges he termed ‘lateral moraines’.
Reading the Rocks Page 14