Lyell published his first scientific papers in 1825. The following year he became a fellow of the Royal Society and in the spring of 1831 he sought and won an appointment as professor of geology at the new (Anglican) King’s College London (founded in 1829 to counterbalance that ‘godless college in Gower Street’, the new secular London University). King’s being a clerical institution, the decision on Lyell had to be approved by no less than the Bishop of London, the Archbishop of Canterbury, the Bishop of Llandaff, and two doctors. The prelates, Lyell informed Mantell, ‘considered some of my doctrines startling enough, but could not find that they were come by otherwise than in a straightforward manner . . . and that there was no reason to infer that I had made my theory from any hostile feeling towards revelation’.13 (He was also honoured with an MA from Cambridge.) Fortunately for Lyell, King’s seems not to have heard of his wish, expressed to the geologist Poulett Scrope, who was about to review Principles, ‘to free the science from Moses’.14
The success of Principles – written in his lawyer’s rooms in the Temple and Gray’s Inn – sparked great interest in Lyell’s forthcoming lectures. Some among Lyell’s friends wished that ladies (mainly their wives and daughters) might come to hear them. But Lyell, in the misogynist tradition of his time, thought it would be ‘unacademical’ to admit women into the classroom.15 In the end a few were admitted and the audience at his King’s lectures swelled to nearly 300. The lectures were judged a great success, not least by Lyell himself. As he wrote to his fiancée, Mary Horner: ‘I kept the attention of all fixed, by not reading, & you cd. have heard a pin drop when I paused.’16
Lyell felt he worked hard in his second lecture on the delicate subject of the relation of geology to natural theology, the branch of theology that attempts to prove the existence of God from natural observations. He had a good audience, including many of his friends and King’s professors. He concluded with what he saw as a ‘noble and eloquent passage’ from the Bishop of London’s inaugural discourse at King’s, which proclaimed that ‘Truth must always add to our admiration of the works of the creator [so] that one need never fear the result of free enquiry.’17 Science, in short, could only glorify God. For this declaration, he was applauded.
Once appointed to King’s, however, Lyell was disappointed to find that, as in Oxford, the geology lectures were extracurricular and therefore he could expect little income from fees for his lectures given on Tuesdays and Thursdays. For him this was a setback for, unlike many of the other early geologists, he was not wealthy and needed an income. When the publisher John Murray of Albemarle Street paid him the hefty sum of £400 (the equivalent of about £20,000 today) for the first edition of Principles, with a promise of further payment for future editions, Lyell saw that his future might lie in authorship. He resigned from King’s, even though he had been there only two years.
In a journal entry intended for Mary Horner, Lyell spelled out his thoughts: ‘If I could secure a handsome profit in my work, I should feel more free from all responsibility in cutting my cables at King’s College. Do not think that my views in regard to science are taking a money-making, mercantile turn. What I want is, to secure the power of commanding time to advance my knowledge and fame, and at the same time to feel that in so doing I am not abandoning the interests of my family, and earning something more substantial than fame.’18
When the first volume of Principles sold out, Lyell knew he had made the right decision. He warmed to the compliment he received from Murray: ‘There are very few authors, or ever have been, who could write profound science and make a book readable.’19
Principles would soon have a great influence on the young Charles Darwin, twelve years Lyell’s junior (and a future close friend). The twenty-two-year-old Darwin, on the recommendation of his Cambridge tutor John Henslow, took the first volume of Principles with him as he set out in 1831 on his long voyage as naturalist on HMS Beagle. He set himself the task of reading it all before the ship reached its first stop.
Lyell’s book alerted Darwin to the danger of ‘undervaluing greatly the quantity of past time’.20 It described, as if in anticipation of Darwin’s visit in 1834, the five-foot elevation of part of the coast of Chile by an earthquake. When Darwin reached Chile, he witnessed for himself a devastating quake and tidal wave in Concepción.21 But far more important was the effect that Principles had on Darwin’s train of thought. It stirred him to wonder about the changes in life forms over time. He shifted his attention from rocks and fossils to man – a direction that would lead him to write On the Origin of Species, the world-changing book that appeared in 1859.
Lyell’s Principles appeared in a Britain ready for new ideas. The bold Reform Bill of March 1832 had widened the voting franchise (even if only slightly) to adult male property owners. For the first time they were given the right to choose who should represent them. The bill created ninety-eight new seats and enabled fast-growing industrial cities such as Birmingham and Manchester to elect a Member of Parliament for the first time.
When Lyell’s influential work first appeared, the age of the earth was accepted to be about 6,000 years. The Christian churches had ceased to take the Bible’s ‘Six Days of Creation’ literally as six twenty-four-hour days. Rather, they had expanded the ‘days’ to a thousand years each – relying on the calculations of Archbishop James Ussher of Armagh in 1650. Ussher had reached the date methodically. He worked out the lifespans of the descendants of Adam. Combining these with his knowledge of the Hebrew calendar and other biblical records, the archbishop came up with the precise time of creation: the evening preceding Sunday, 23 October 4004 bc.22 This date, widely accepted as fact, was printed in the margins of texts of the Book of Genesis.
From its start, geology challenged established religion. Excavations for coal mines and rail tunnels revealed fossils and ancient rocks which clearly had formed over more than 6,000 years, let alone in six days. The new science raised the tantalising question: did the biblical Flood have a geological basis? The Geological Society of London, founded in 1807, answered with a resounding ‘No’. It refused to equate Noah’s Flood with a universal deluge – much to the dismay of some religious believers within its ranks who had hoped that geology would confirm Genesis. As Jim Endersby, the Cambridge University historian of science, has expressed their dilemma: ‘If, as the Bible claimed, this planet had been made as a habitation for humanity, why had its creator taken so long to get the tenants in?’23
In Britain, in particular, geology provoked a crisis of faith. While in France the Revolution had broken the grip of the Roman Catholic Church on the state, the Anglican Church of England had great political and intellectual influence on the expression of ideas. At Oxford and Cambridge, the professoriat were mainly beneficed clergy who received an ecclesiastical living from the Church. Moreover, as many as two-thirds of their students planned to take holy orders when they left university. What were they to preach about the place of humanity in nature?
Lyell began his Principles convinced that the process of geological change had been slower than anyone had imagined. It was now accepted that natural processes were manifestations of energy acting on or through matter. Volcanic eruptions were no longer seen as an expression of the anger of the gods of the underworld. Lyell, with his lawyer’s training, knew how to make a good case. Principles introduced his readers to the new concept of an ancient earth. It went on to divide the ‘agents of change’ into the Aqueous (such as estuaries caused by the water of seas, rivers and tides) and the Igneous (the formation of mountains such as Vesuvius and Etna by a long series of volcanic eruptions over an immense period of time). Lyell freely acknowledged his debt to the Scottish physician and naturalist of the eighteenth century, James Hutton (1726–97).
In his two-volume work Theory of the Earth, Hutton declared that, after studying the continents and coasts of the earth, he found a balance between lands being created and destroyed.24 Lyell, in his own book, called attention to the bold assertion Hutton had
made before the newly formed Royal Society of Edinburgh, when he declared that he was attempting to explain changes in the earth’s crust by natural agents. ‘The ruins of an older world are visible in the structure of our planet,’ Hutton said, ‘and the strata which now compose our continent have been once beneath the sea, and were formed out of the waste of pre-existing continents.’25 Hutton himself read the varied layers of rocks as evidence that the earth’s age had to be measured in millions, not thousands, of years. He recognised that sediments had been laid down slowly at various times in the past, then heaved up and sometimes penetrated by igneous intrusions.
Hutton discovered what is now called ‘deep time’ on his Scottish acres. As a gentleman-farmer, as well as a naturalist, physician and chemist, Hutton had watched with dismay as the rains poured down on his Berwickshire fields, carrying away the soil and depositing it into streams. Why, Hutton wondered, had God created land only to destroy it?
Deeply devout, he answered his doubts with religious reasoning: the divinely ordered process was not only destroying land but creating it at the same time by washing down sediment from hills and mountains. In March and April 1785 he presented his theory of the earth as a system to the Royal Society of Edinburgh. He was more than an inquiring scientist; at times he could be a gifted phrase-maker. In the first volume of Transactions of the Royal Society of Edinburgh published three years later he created a stir with what became his most memorable declaration: that in his study of the earth he had found ‘no vestige of a beginning, no prospect of an end’ – a phrase that Lyell was to misquote in Principles as ‘no traces of a beginning, no prospect of an end’.26
Hutton’s Scotland was a fitting birthplace for British geology. The country’s spectacular scenery forces the most casual observer to wonder how the rocks got that way. An extinct volcano, Arthur’s Seat, looks down on the capital, Edinburgh, whose western border is formed by the dramatic Salisbury Crags. As a boy Hutton would have seen the large hollow in Arthur’s Seat, created in 1744 by the great landslide which exposed a large piece of volcanic rock.27
Another of Hutton’s assertions – that granite was a young rock – in itself challenged the biblical view of creation, which held that everything had been made at the same time. Looking for evidence to prove his theory, in September 1785 Hutton headed northeast from Edinburgh to the Grampian Hills and Glen Tilt to the confluence of two great rivers, the Dee and the Tay. There he found veins of red granite traversing black schist and primary limestone. The striking contrast of colours and textures showed that the granite had flowed molten into the limestone. In other words, the landscape had changed dramatically; the two kinds of rock had not appeared simultaneously. Hutton then took the pattern as evidence that the earth’s age had to be measured in millions of years, rather than thousands.
Better proof was to be found not far away and Hutton sought it to answer his sceptics. In 1788, with two friends (both unconvinced by his ancient earth theory) and assisted by several farmhands, sixty-two-year-old Hutton headed in a boat along the southeast coast of Scotland to the cliffs of Siccar Point. There he made one of the most celebrated geological discoveries in history. The men did not need a single hammer to get the meaning of the rocks. They looked up at a dramatic promontory. At its base, vertical grey rocks stood in parallel, like a row of books. Overlying these lay flat layers of red sandstone. The two rock types of totally different composition in juxtaposition formed a classic picture of what geologists call ‘unconformity’.
To Hutton and his two learned companions – John Playfair, a forty-year-old professor of mathematics at the University of Edinburgh, and a wealthy twenty-seven-year-old geologist, Sir James Hall of Dunglass – it was glaringly obvious that the vertical grey slabs had once been flat sand on the sea floor. Over vast time these sediments had been turned into rock – literally petrified. Then earth forces had slowly tilted the whole mass onto its side (by crustal processes now understood to have been continental drift and subterranean heat) and new deposits had arrived on top, slowly solidifying into rock themselves.
The message of Siccar Point was inescapable. The three men were facing visible proof that Archbishop Ussher’s calculation of the earth’s age at around 6,000 years was wrong. Ludicrously wrong. Hundreds of millions of years had to have passed for the mass of Siccar Point to have reached the configuration they saw.
Today it is estimated that the grey lower layers of Siccar Point’s rocks were deposited about 425 million years ago and the overlying red sandstone about 80 million years later. Deep time indeed.
Another scientist immersed in ascertaining the great age of the earth was the French mathematician, astronomer and physicist of pre-Revolutionary France, Georges-Louis Leclerc – known from 1725 as the Comte de Buffon. Buffon based his experiments on his knowledge that the earth’s centre was hot (as those who dug mines knew very well). Heating two dozen small metal globes until they were glowing red, he then measured the rate at which these cooled to the point where he or his assistants could hold them in their hands. From this experiment he first placed the earth’s age at 43,000 years, then amended it to 75,000 years.
For more than three decades Buffon had been preparing a comprehensive forty-four-volume Histoire Naturelle, of which three dozen volumes had been published by the time of his death in 1788. These and subsequent posthumous volumes encompassed his ambition to explain all of natural history, geology, anthropology and optics in a single encyclopaedic work. Into his massive text Buffon quietly inserted his startling view that the earth was many thousands of years old. He also allowed himself to venture that living species changed through time. In addition, he was the first to point out that different animals and plants were to be found in different parts of the world, citing the absence of what he called ‘species identity’ between the four-footed animals of North America and Europe.28 Remarking on the similarities between humans and apes, he audaciously suggested they might have a common ancestry. For this bold idea Buffon has been declared a pioneer in the theory of inheritance of acquired characteristics.29 Accused of heresy, Buffon formally recanted but quietly clung to his ideas.
Today, the eminent palaeontologist Richard Fortey believes that Buffon deserves admiration. ‘Count Buffon may have got his estimate of the Earth’s age based on its hypothetical cooling from the molten state entirely wrong,’ he states, ‘but he felt free to make an estimate without nodding to religious authorities or anyone else . . . assessment of time was part of a more general scepticism in the age of free enquiry. Britain was rather late on the scene.’30
In 1795 Hutton went on to publish his theory of the earth, declaring: ‘With such wisdom has nature ordered things in the economy of this world, that the destruction of one continent is not brought about without the renovation of the earth in the production of another.’31 He spelled out his conviction that the earth must be millions of years old in order to have produced Siccar Point. What had solidified the strata of loose materials on the ocean floor? Hutton’s answer was ‘the power of heat and operation of fusion’ – a doctrine that is fairly accurate by today’s knowledge, which places the temperature of earth’s outer core as around 3,000 degrees Celsius.32
Had Hutton been able to write expository prose as well as, say, Lyell, he himself might have been recognised as geology’s founder. But he wrote clumsily and chose to include in his book many unwieldy passages in French. Moreover, the obvious conflict with the Bible would cause Hutton to be reticent about his discovery. Having been called an atheist when he presented his ideas to the Royal Society of Edinburgh a few years earlier, he did not want to call undue attention to the glaring conflict of geology with Genesis.33
It was not until 1802 that Hutton’s friend, John Playfair, a far better writer, penned Illustrations of the Huttonian Theory of the Earth, and made Hutton’s discoveries accessible. (Lyell, preparing his Principles, relied heavily on Playfair’s Illustrations.) In his own book, Playfair described seeing Siccar Point: ‘We felt ourselv
es necessarily carried back to the time when the schistus on which we stood was yet at the bottom of the sea . . . The mind seemed to grow giddy by looking so far into the abyss of time.’34
In 1987, Hutton’s eighteenth-century discovery was acclaimed by the eminent science writer, Stephen Jay Gould. In Time’s Arrow, Time’s Cycle, he wrote of Hutton: ‘He burst the boundaries of time, thereby establishing geology’s most distinctive and transforming contribution to human thought – Deep Time.’35 The discovery, said Gould, imposed a ‘great temporal limitation’ upon human importance: ‘the notion of an almost incomprehensible immensity, with human habitation restricted to a millimicrosecond at the very end!’36
Today, from measuring the radioactive decay of carbon, uranium and other elements, scientists estimate the age of the earth at roughly 4.6 billion years. The encompassing solar system is believed to have emerged around 13.7 billion years ago as a result of the ‘Big Bang’ – the collapse of a fragment of a giant molecular cloud. The earth, like other planets, was then formed by accretion from a rotating disc of dust and gas. Dense materials such as iron sank into the core. Lighter silicates and water rose near the surface. Four layers formed: inner core, outer core, mantle and crust – the inner core so hot that the outer core has remained molten. Most of the earth’s mass lies in the mantle, a solid covering that can deform slowly in a plastic manner. The external crust is rocky and brittle, fracturing when the earth quakes.
By far the longest part of the earth’s history is now understood to have been the time before any form of life began – an estimated 3.9 billion years. Only comparatively recently – an estimated 540 million years ago – did life emerge, first as single cells deep in the ocean, then as creatures with heads, tails and segmented bodies. This period is now referred to as the ‘Cambrian explosion’.
Reading the Rocks Page 2