Martin J. S. Rudwick, Georges Cuvier, Fossil Bones, and Geological Catastrophes: New Translations & Interpretations of the Primary Texts, University of Chicago Press (paperback and e-book, 1998, ISBN 978-0226731070).
Robert Jameson’s 1818 translation, published under the title Essay on the Theory of the Earth, is archaic in spots but still perfectly readable; it can be found in a number of free e-book versions, as well as in many library collections.
Georges Cuvier, Essay on the Theory of the Earth, trans. Robert Jameson, Kirk & Mercein (hardcover [out of print] and e-book, 1818, no ISBN).
* * *
* “Culm” was the term used for a particular kind of anthracite found in the southwest of England.
FIFTEEN
A Long and Steady History
Uniformitarianism becomes the norm
The order of nature has, from the earliest periods, been
uniform.
—Charles Lyell, Principles of Geology, 1830
In 1830, the geologist Charles Lyell weighed in on Hutton’s side of the argument. And his arguments for long, slow change were so forceful that catastrophism was thrown out of the geologists’ vocabulary—for a century and a half.
Charles Lyell, a fellow Scot, had been born the same year that Hutton died. He had gone up to Oxford in 1816, intending to read law; but the earth was his hobby, and he spent a good part of his second year attending the geology lectures given at Corpus Christi by William Buckland.
Buckland, himself trained in chemistry and mineralogy, was an ordained clergyman as well as an enthusiastic geologist. He was a disciple of Cuvier, a vigorous supporter of catastrophism, and (like the majority of his contemporaries) a believer in Genesis. Like the fictional Telliamed, he saw no conflict between geology and faith: “As far as it goes,” he explained in his lectures, “the Mosaic account is in perfect harmony with the discoveries of modern science.” The creation account in Genesis hit the high points of the earth’s history (its original creation and the rise of the human race); geology filled in the details.
If Geology goes further, and shews that the present system of this planet is built on the wreck and ruins of one more ancient, there is nothing in this inconsistent with the Mosaic declaration, that the whole material universe was created in the beginning by the Almighty: and though Moses confines the detail of his history to the preparation of this globe for the reception of the human race, he does not deny the prior existence of another system of things.1
Young Lyell found this pronouncement entirely persuasive. In 1818 he accompanied Buckland on a field trip to Paris: “Went to the Jardin des Plantes,” he wrote in his diary, “where I again looked over Cuvier’s lecture-room, filled with fossil remains, among which are three glorious relics of a former world.” Those former worlds had been wrecked multiple times, in the gap between God’s original creation of the earth and the divine reintervention that brought about man.2
But as time went on, Lyell found himself less and less satisfied by Cuvier’s scheme. He had plenty of time to think about it, since he was (like most early geologists) independently wealthy; after Oxford he made a desultory stab at practicing the law and then gave it up to spend his time mastering all of the different fields of knowledge necessary for the study of the earth (his own list included “chemistry, natural philosophy, mineralogy, zoology, comparative anatomy, botany; in short, . . . every science relating to organic and inorganic nature”). He spent time in the field, journeying throughout Scotland to examine the sediment layers in rocky hillsides and remote lakes; he joined the Geological Society of London and presented papers about his findings; he corresponded with other earth scientists.
In 1825 Lyell made the tentative suggestion that catastrophe wasn’t necessarily the cause of past phenomena. “In the present state of our knowledge,” he wrote in the London journal Quarterly Review, “it appears premature to assume that existing agents could not, in the lapse of ages, produce such effects.” Extraordinary, earth-wrecking disasters could have produced the specimens in Cuvier’s collections. It had certainly not been disproven, though, that the “existing agents” still at work in the world—plain old erosion, the common rise and fall of temperatures, the regular wash of the tides—might be responsible instead.3
It would just take them a whole lot longer.
For several more years, Lyell looked for proof that those “existing agents” could, over time, act with as much power as Cuvier’s catastrophes. Three years later, in the Limagne plain of France, he found tracks of an ancient riverbed that seemed to have eaten an enormous trench into granite and lava layers, in a pattern that could not possibly be chalked up to deluge or upheaval, but only to the long, slow “progress of ages.” “This is an astonishing proof,” Lyell wrote back to his father, “of what a river can do in some thousand or hundred thousand years by its continual wearing.” Afterward he traveled across Sicily, ascended Mount Etna, and hiked into the south of Italy, all the time finding more and more geologic evidence that ancient and modern causes were the same.4
Underlying all of these discoveries was Lyell’s growing conviction that catastrophism was a dead end for geology as a science. If onetime past events were responsible for the current form of the earth, there was no way that the geologist could truly understand the present by exercising reason. The geologist could always haul in a disastrous flood, or a passing giant comet, or some other event that could never be experimentally reproduced, to explain the planet. Geology would remain the study of history, mixing story and interpretation with observation, filled with speculations that could never be scientifically proved.
By the end of his Italian trip in 1829, Lyell had determined to lay out the principles that would make geology into a true science. Sitting in a Naples inn, he wrote to a friend that his book on the subject was already “in part written and all planned”:
It will not pretend to give even an abstract of all that is known in geology, but it will endeavour to establish the principle of reasoning in the science; and all my geology will come in as illustration of my views of those principles.
Those principles would make it possible for geologists to conduct their science with the same rigor that Newtonian physics or Galilean astronomy demanded:
No causes whatever have from the earliest time to which we can look back, to the present, ever acted, but those now acting; and . . . they never acted with different degrees of energy from that which they now exert.5
Only forces that could be presently observed would be admitted to Lyell’s encyclopedia of explanations. He intended, he wrote in another letter, to understand the earth
without help from a comet, or any astronomical change, or any cooling down of the original red-hot nucleus, or any change of inclination of axis or central heat, or volcanic hot vapours and waters and other nostrums, but all easily and naturally.6
When Lyell published the first volume of his guide to geology in the following year, he chose a title that made this commitment perfectly clear: Principles of Geology, Being an Attempt to Explain the Former Changes of the Earth’s Surface, by Reference to Causes Now in Operation.
Over the course of twenty-six short chapters, Lyell laid out three interlocking principles for geology, now generally known by the names actualism, anticatastrophism, and (more awkwardly) the earth as a steady-state system.
Actualism. Every force that has acted in the past is still acting (and can be observed) in the present.
Anticatastrophism. Those forces did not act with more intensity in the past; their degree has not changed.
The earth as a steady-state system. The history of the earth has no direction or progression; all periods are essentially the same.7
Two years later, the English natural philosopher and clergyman William Whewell gave Lyell’s principles the label by which they have been known ever since: uniformitarianism.
The Principles of Geology instantly sold out. Lyell’s careful marshaling of evidence, his clear writing, and his
repeated (perhaps not entirely sincere) assurances that he did also believe in a Designer won most of his English readers over at once. Over half a century later, the naturalist and philosopher Alfred Russel Wallace summed up the British success of the Principles:
But in 1830, while Cuvier was at the height of his fame and his book was still being translated into foreign languages, a hitherto unknown writer published the first volume of a work which struck at the very root of the catastrophic theory, and demonstrated, by a vast array of facts and the most cogent reasoning, that almost every portion of it was more or less imaginary and in opposition to the plainest teachings of nature. The victory was complete. From the date of the publication of the “Principles of Geology” there were no more English editions of “The Theory of the Earth.”8
The theory took a little longer to catch on in Europe. But it was so clear, so rational, so sensible, that geologists across the globe ultimately embraced it.
And continued to embrace it. In the 1960s, writes American geologist Walter Alvarez, uniformitarianism was still the “dogma” of the field, and “the established wisdom of our science was that nothing really dramatic—no catastrophes—had ever happened in the planet’s past.” Long, slow, gradual change had become the only change admissible in the new science; Lyell had triumphed.9
To read relevant excerpts from the Principles of Geology, visit http://susanwisebauer.com/story-of-science.
CHARLES LYELL
Principles of Geology
(1830–32)
Most available editions of the Principles of Geology contain all three volumes, written between 1830 and 1832. Originally, Lyell had planned to write just two volumes, one dealing with his overall principles (Volume 1), and the second providing more specific geologic proofs (now Volume 3). Eventually, though, he realized that he had to give some accounting for the fossil record, so he interposed a new volume (the current Volume 2). For the purposes of geology, you need to read only Volume 1, which lays out the principles of uniformitarianism.
The original 1830 text can be read online or downloaded as a PDF from multiple sources. Penguin has also produced a high-quality paperback, edited by James A. Secord, containing a useful introduction and all three volumes.
Sir Charles Lyell, Principles of Geology, Being an Attempt to Explain the Former Changes of the Earth’s Surface, by Reference to Causes Now in Operation, vol. 1, John Murray (e-book, 1930, no ISBN).
Charles Lyell, Principles of Geology, ed. James A. Secord, Penguin Books (paperback and e-book, 1997, ISBN 978-0140435283).
SIXTEEN
The Unanswered Question
Calculating the age of the earth
Many of the fundamental problems of geology can be solved
only with reference to the processes involved in the making
of the earth.
—Arthur Holmes, The Age of the Earth, 1913
Lyell’s fierce campaign against extraordinary events had been astoundingly successful.
In fact, nearly a hundred years after the publication of the Principles, it remained quite déclassé for a geologist to theorize about past events in the earth’s history that could not be explained by the present. Such speculations smacked of seventeenth-century theologizing, of biblical creationism, of the years before geology became a science.
The problem was that strict uniformitarianism left the single biggest question in geology unanswered.
Like the fictional Telliamed, Charles Lyell had tried to evade the question of origins by assigning it to religion, not geology. “Probably there was a beginning,” he wrote to an early reviewer of the Principles, “—it is a metaphysical question, worthy a theologian—probably there will be an end.” But that was as far as he could go. Uniformitarianism made it impossible for him to contemplate any theory of origins, because beginnings (and endings) implied that the past (and future) did differ from the present.
Lyell could not entertain the idea that the earth had originally been a molten ball cooling over an incredibly long time, any more than he could agree that God had opened the heavens and sent a miraculous deluge in the days of Noah. Theories of beginnings had the potential to short-circuit Baconian reasoning, to introduce new and inexplicable past causes as an easy alternative to true understanding. “All I ask,” Lyell wrote, just before publication of the Principles, “is that at any given period of the past, don’t stop inquiry when puzzled by refuge to a ‘beginning.’ . . . We are called upon to say in each case, ‘Which is now most probable, my ignorance of all possible effects of existing causes,’ or that ‘the beginning’ is the cause of this puzzling phenomenon?”1
But the earth was a complicated object of study. Unlike the laws of physics, or the principles of chemistry, the earth was a place, a thing with a history. It bore on its surface the tracks of a long past. It was home to a species that lived in time. “John Heddon, aged 31,” began a typical nineteenth-century English news report, “and Thomas Gaydon, aged 68, fell over a scaffolding to the ground.” The age of the men involved might seem to have nothing to do with the event; but the time that someone (or something) has been in existence changes the way that human beings understand it. We do not easily exist in ahistoricity.2
So it is not surprising that, post-Lyell, a number of thinkers attempted to reconcile the general principles of uniformity with the human compulsion to estimate the age of the earth.
Thirty years after the Principles, the Belfast-born mathematician William Thomson—later known as Lord Kelvin—applied a universal law to the solar system and came up with both an end and a possible beginning. The universal law was the Second Law of Thermodynamics: When energy is converted from one form into another, some of it is always expended in the process.* The sun is a natural engine that converts energy into heat. Ergo, the sun is losing energy with every conversion. So in the past, it must have been hotter than it now is; and in the future, it will continue to cool.
In other words, uniformity didn’t imply stasis, lack of development. If we accept, Thomson wrote, that “known operations going on at present in the material world” are the only ones that have acted in the past, the conclusion is simple: “Within a finite period of time the earth must have been, and within a finite period of time to come the earth must again be, unfit for the habitation of man.” Uniformity meant that the earth had changed, drastically, over time. The sun itself could not be older than five hundred million years (with a hundred million years a more likely figure); so the earth could not have orbited it eternally, and one day the earth would cease to orbit it again.3
Two years later the Irish physicist John Joly used the amount of sodium that had leached from the earth into ocean water (an ongoing, observable process) to estimate that the oceans were about a hundred million years old. His effort, like Thomson’s, honored Lyell’s principles.
One hundred million years was a long time. Five hundred million years was even longer. But neither was quite long enough to accommodate Lyell’s strict uniformitarianism. Those slow, gradual transformations needed even more time.
•
In the first quarter of the twentieth century, a new method of dating arrived on the geologic horizon.
In 1895 the German physicist Wilhelm Roentgen had observed “mysterious rays,” streams of energy particles that could penetrate solid matter, in his laboratory; he called these “X-rays,” not having any other way to label them. The following year, another physicist, the Parisian Antoine-Henri Becquerel, discovered similar “rays” emitted from uranium salts. In 1898, Marie S. Curie and Pierre Curie observed the same phenomenon, this time rising from thorium. The Curies named the rays radioactivity and suggested that the particles streaming from thorium and other elements came not from molecules, but from individual atoms themselves.†
Four years later, physicist Ernest Rutherford and chemist Frederick Soddy concluded that those atoms were actually disintegrating. They were unstable (perhaps because they were too massive, or had too much energy) and so were
throwing off particles to try to keep their equilibrium. And the rate of their disintegration was measurable, constant, predictable.4
Which meant, Ernest Rutherford suggested, that minerals containing an unstable element could be dated by measuring the progress of the decay: “a most valuable method of computing their age,” he wrote, in 1906. “Indeed, it appears probable that it will prove one of the most reliable methods of determining the age of the various geological formations.” He was unable to give a precise measurement, but he had a range in mind: “Many of the primary radioactive minerals,” he concluded, “were undoubtedly deposited at the surface of the earth 100 to 1000 million years ago.”5
One hundred million years was no shock to Rutherford’s readers. But one thousand million years—that was moving toward an entirely different time frame.
•
In 1906, Arthur Holmes was sixteen years old: raised as a devout Methodist, preparing to study physics at university, perplexed by the marginal notes in his Bible. “I can still remember the magic fascination of the date of Creation, 4004 BC, which then appeared in the margin of the first page of the Book of Genesis,” he noted, later in his life. “I was puzzled by the odd ‘4.’ Why not a nice round 4000 years? And why such a recent date? And how could anyone know?” His physics studies at the Royal College of Science coincided with the rising interest in Rutherford’s new dating techniques; halfway through his degree, Arthur Holmes changed his field from physics to geology.6
Geology was in a mild uproar. William Thomson (who had become Baron Kelvin in 1892) had just died, at eighty-three, leaving behind an estimate of the earth’s age that had steadily shrunk from his original upper estimate of five hundred million years down closer to twenty million as he had calculated and recalculated. Rutherford’s “radioactive dating” had yielded wildly varying results; the breakdown of radioactive elements was still poorly understood, and measuring the decay left behind was a complicated and variable business. Arthur Holmes, first as an undergraduate and then as a doctoral student, immersed himself in the brand-new and entirely unstable field of radioactivity.
The Story of Western Science Page 14