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Charles Lyell and deep time


Time is of the essence, or so the saying goes. But is an awareness of the magnitude of time really essential to humanity? Is it possible to invent time? Richard A. Fortey* writes on Charles Lyell, high priest of deep time.

Editor's note:  This is a slightly longer version of the article published in the print issue.

Geoscientist 21.09 October 2011

How much time do we need to make sense of our place in the universe? What has the discovery of the geological time scale done to our perception of our role in nature? It seems that the awareness of the magnitude of time has had as profound an influence on the human psyche as the discovery of the laws of motion or the structure of matter.

One might say that Charles Lyell was instrumental in discovering time - geological time. Or to be more accurate, he presented evidence for the existence of the time necessary to explain geological history in the most persuasive way. After all, he was a lawyer by training, and he knew how to make the best case. We anglocentrics tend to think that the “discovery” of time is something with which we can credit British science. The conventional story has it that the Scottish Enlightenment threw up James Hutton, a very astute observer in the field looking at real rocks, and unlike aristocratic savants who theorised comfortably about the Earth from their armchairs. Hutton presented his findings to the Royal Society of Edinburgh in 1785 in his paper “Concerning the system of the earth, its duration and stability”. Many geologists probably remember his famous phrase referring to time: “no vestige of a beginning, no prospect of an end”- from his 1788 paper read before the same society. Other geologists will have visited the volcanic rocks of Arthur’s seat in the middle of Auld Reekie to see where Hutton and James Hall deduced that the rocks there had indeed been erupted as hot lavas. They saw evidence of cooled margins and other features that asserted the primacy of trenchant observation in determining geological origins. Many colleagues have even trudged along the Berwick coast to the famous unconformity at Siccar Point which shows where the hand of time has been placed on one particular rocky outcrop.

Kinnordy That site is often considered symbolic of the moment (in time, of course) when it became necessary to think in terms of millions of years, not mere thousands. We recall that in the seventeenth century Archibishop Ussher had computed the age of the Earth by totting up the generations mentioned in the Bible until he arrived at Creation. 4004 B.C. is still one of those dates that lodges in the mind, like 1066 and all that. Humans are somehow comfortable with thousands: it sounds enough to be a lot, but it is still graspable. As noughts proliferate on the ends of numbers they become more and more nebulous. Can anyone look at a small heap of sand and say there are 50,000 grains there, or 500,000 or 2 million? It requires courage to take the intellectual step to go beyond the comfort zone into the millions; to truly understand antiquity.

Image:  Kinnordy, Forfarshire - birthplace of Charles Lyell.

Hutton is probably poorly known in the world at large by comparison with his Enlightenment friends, Adam Smith or David Hume. At Siccar Point, which is a few miles west of St Abb’s Head, he noticed that rocks that had originally been laid down under the sea had been tipped up vertically. They had then been worn down, slowly, slowly, to a point where more sandstone could be deposited horizontally on top of their eroded remnants. The earth must have been convulsed to twist rocks upwards so, and then what aeons must have passed to wear them down again until sands could flood across their planed-off contours? Hutton’s disciple and companion John Playfair visiting the same place in 1788 remarked that “The mind seemed to grow giddy looking so far into the abyss of time”. Giddy but perhaps exhilarated, since generous, indeed inconceivably long, swathes of time allow for a new vision of the planet, wherein mountains can be reduced to sea level by action no more vigorous than frost, wind and rain. Somewhere lurking in the background was the implication that mankind’s own time might be no more than the last tick on the geological clock.

It’s important to note at this point that Hutton’s view of time seemed literally endless. He was attracted to the idea of perpetually repeating erosional cycles of construction and decay – almost mechanical in their way, like the rotation of the planets around the Sun, with ‘no vestige of a beginning’. One might say that he instinctively recognised an almost Gaia-like affinity with the planet.

Lyell Thanks to Martin Rudwick’s unparalleled historical researches, laid out in his book ‘Bursting the Limits of Time’, we know now that Hutton was not quite the pioneer we like to think. In fact, as so often in other scientific matters, there had been precedents for several decades over in France. The French savants before the revolution were able to take their minds into the million of years. They exchanged correspondence between themselves in what has been referred to as the Academy of Letters, without worrying too much who might have been looking over their shoulders. Some of them were even clerics, although I wouldn’t want to suggest that clerics were necessarily anti-science. The Count Buffon may have got his estimate of the Earth’s age based on its hypothetical cooling from the molten state entirely wrong – but the important point is that he felt free to make an estimate without nodding to religious authorities or anyone else. The freedom of thought that eventually took a revolutionary turn in France subsequently primed the minds of free-thinking souls elsewhere in the world (and remember there were strong Scottish-French connections in those extraordinary times). So assessment of time was part and parcel of a more general scepticism, when the spirit of the age began to be one of free enquiry. Matter and mathematics were all part of it. And if Rudwick is right we in England (pace Scotland) were rather late on the scene. But Buffon’s estimate, however inaccurate, does presuppose a finite age for the Earth – an origin, in fact – which differs greatly from Hutton’s perpetual motion machine.

Another factor in the temporal brew that is sometimes overlooked is the importance of maps. I was reminded of this while reading Rachel Hewitt’s recent history of the Ordnance Survey Map of a Nation. The eighteenth century was map mad. Helped by new technology such as the Great Theodolite, the Georgians mapped just about everything: the stars, geography, topography, seas and - early in the nineteenth century - William Smith’s map outlined the geology of Britain. Smith, of course, as a practical engineer was concerned only with utility, not with time: he wanted to know where to push canals and open up quarries. But that map became almost immediately a narrative – of the succession of strata laid out in their beautiful colours – and every narrative requires one thing above all else: and that is a time frame.

Inscribed copy of the Principles in the Society's collection Image - Inscribed copy of the Principles in the Society's collection

So you might say that Lyell was the right man at the right moment in history. This was also a period when the Geological Society of London was one of the most cutting edge societies in the capital. It was also free-thinking – many of its founding fellows were religious Dissenters and Quakers. It wasn’t a conventional place, for all that it denied William Smith the recognition he so deserved for several years. Whatever the surrounding circumstances, there cannot be much question that Lyell’s Principles of Geology of 1830 (and following years) wrapped up the new science in acceptable packaging. The Geological Society provided an appropriate forum for airing its implications. Taken together, these circumstances were also instrumental in diverting the leading edge of the fledgling science from France to the English-speaking world. Its mixture of demonstrable cases studied in the field with theory – usually wrapped up in the term uniformitarianism – gave a new kind of lens through which to view nature. We wouldn’t today accept the idea that geological history was a smooth story of processes operating always in the past as they do today – but then Lyell was reacting against the catastrophism of Baron Cuvier over the Channel – and chose the model that offered the clearest ground between them. I might also mention that geologising was a socially acceptable, even fashionable thing to do. Gentlemen, and ladies of refinement, could make their contribution. It never does much harm to be à la mode.

If Lyell is known to the general public today, it is probably mostly because Charles Darwin took his books with him on the Beagle even as they were published. I have lost count of the number of times I have heard that restated during Darwin’s Bicentenary year, but this should be an occasion when familiarity should not breed contempt. Darwin and Lyell were regular correspondents later. And of course Lyell’s gift of time and process informed all of Darwin’s geological observations on his great voyage. Lyell donated the time frame in which evolution could operate. It was the missing ingredient from the concoction that would become the unifying theory of all biology. Although Darwin famously took years to formally set down the details of natural selection, Lyell’s way of looking at the world formed his weltanschaung. Time made life work.

Title page - showing the However, once the time barrier had been breached, it was only a question of how much time. The stratigraphical divisions of the geological column, the periods such as Devonian or Cambrian, with which we are now so familiar, were themselves being refined and put into the right sequence through the same historical period. Just to have a sequence of labels helped geologists grapple with time, and, in a strange way, labels domesticate time. At the visceral level for us humans used to a scale of a few generations, the difference between tens of millions, hundreds and indeed billions of years causes us to nod wisely, but is difficult truly to grasp. The discovery of radioactive clocks was to harden these figures in the 20th century, and indeed another prominent British geologist, Arthur Holmes, played a central role in determining the age of the earth. However, the end points of the calculations matter profoundly, the age of universe at about 13.7 billion years, the beginning of everything, and the age of the Earth at 4.5 billion years, the point at which our own history began. The knowledge that the universe, solar system and Earth all themselves evolved through billions of years changes our relationship with the natural world. We are part of that story, but right at the end, like a punctuation mark at the end of the Bible. It still makes many people squeak with pain to feel like such an afterthought. There are even those who deny the timescale. I occasionally log into a creation science post to see how geological strata are still capable of being interpreted as the product of the biblical Flood. The tone of voice of these postings is rather like the liberal bashing of the right wing shock jocks that take up so much of the airwaves in the United States: “DO they really expect us to believe….?” - you know the kind of thing. Well, yes, we do expect them to believe, because it is very likely to be the truth. The fact that Lyell himself published uniformitarian geological interpretations of North American structure and strata in 1855 seems to have passed such people by completely. I still find it depressing that people can visit the Grand Canyon and accept the idea that it was gouged almost instantaneously.

It is, of course, the notion of the immensity of geological time that is both seminal to our understanding of our place in Nature and simultaneously induces panic in some people. It is truly a transformative idea that it has taken more than four billion years to shape the Earth as it is, that Hutton’s cycles have not only replayed repeatedly but also changed slowly with the evolution of the planet. Lyell himself underplayed the importance of catastrophes in Earth history in favour of slow change and perturbations, like eruptions or earthquakes, commensurate with the Recent. Now we are comfortable with the idea that there were crises as well as continuity. In my own field of palaeontology, the greatest change in our understanding since Darwin has probably been the realisation that most of Precambrian time (to Darwin mysteriously barren) was not only full of life, albeit microscopic, but that the very business of life itself transformed the biosphere. The first appearance of respiring animals was predicated on the appearance of oxygen, and that itself was made by photosynthesising bacteria and plants; thereby transforming an early atmosphere that would have suffocated all higher life. That was the work of two billion years. The origin of life may remain a matter of speculation, but its importance in creating the balanced global geochemical system, feeding the carbon cycles, in mediating erosion, and influencing climate can no longer be gainsaid. Time and life together have made the resources we now plunder with such enthusiasm. I think it is the acceptance of this fact that has spawned a new awareness of the planet’s vulnerability – an awareness sharpened by the images of our Earth taken from space, looking so small and all alone, and yet so comfortably if precariously wrapped in atmosphere and water. What time has mixed together let no man put asunder!

At the same time a sharpened historical view of geological time has proven that the progress (if one can call it that) of the planet has been far from smooth. Climate change, moving continents, and major mass extinctions have re-set the story of evolution more than once. Considerations of time alone made us humans seem important for only the briefest instant of Earth history (and Lyell himself turned to this theme in 1863 in looking for evidence of the antiquity of man); then, if we add in all those geological events, our presence on the Earth might seem no more than a concatenation of accidents. So Lyell set in motion what has become a further dethronement of our species from one at the centre of the universe made in the likeness of God to a kind of historical accident. Was consciousness itself after all just an evolutionary spin-off fundamentally no different from the tail of a peacock or the neck of the giraffe? Are we only the product of natural selection working in the context of climate change in Africa a million or so years ago?

There is at the moment a fashionable kind of macho evolutionary biologist who would concur exactly with those questions and ask no more – Richard Dawkins comes to mind. It’s interesting that a different reading of the same historical scenario might lead (perhaps with Hutton) to a view that our very interconnectedness with our billions of years of history means that we are, or should be, part of a greater Earth system. Our industrial excesses, increases in CO2, not to mention our relentlessly increasing populations, are insulting what four billion years has taken to put together. Extremists of this persuasion might compare us with a rampant weed. Earth systems science probably lies behind such the more holistic view, but I have a feeling that the more muscular reductionists would regard it as liable to become too touchy-feely, or emotionally immoderate to be taken seriously. But whatever one’s personal stance, I do believe that we could place these questions about the meaning of humanity, and what our relationship should be to the planet on which we live, alongside discoveries about the fundamental subatomic building blocks of matter, or questions about the Big Bang; they are issues that affect the deepest aspects of who we are, and what we should do about it. Without the acceptance of processes working through vast stretches of time these questions would have no resonance.

What then of progress? Darwin often wrote of ‘improvement’ with regard to natural selection. Are we Homo sapiens really ‘improved’ in relation to Homo erectus? Was there a sense in which the story of life as played out through time followed the bidding of ‘improvement’? Or, to put in another way, does it have a predictable direction? Lyell’s view of the progressive changes leading to the living fauna (which lay behind his definitions of the subdivision of the Tertiary Era) does imply a sense of progress rather than a random walk. It has even been claimed by Simon Conway Morris that there is a kind of inevitability about what happens in evolution. It is obviously true that large predators having separate evolutionary origins can indeed resemble one another closely. The independent evolution of ‘sabre-tooths’ is a familiar example. Common problems demand common morphological solutions. More prosaically, one could cite things that look like corals originating from different ancestry, or even truffles. But Conway Morris has gone further to claim that a bipedal, large eyed consciously intelligent animal is an inevitable outcome – even predictable – of the way evolutionary events play out on a planet – any planet – despite the interruptions of mass extinctions and other external events that reset the evolutionary program. The genes unwrap predictable parcels on this view. I am sure that it would be anathema to the reductionist school. However, my own reservations about this kind of scenario stem from the fact that I don’t see such speculations as science at all, since, fun as they are, they can never be tested. It is never possible to rerun history, and it is always tempting to look for design. After all, that is one of the things that distinguishes us from our ancestors – well, there again, as far as we know. Of course, I am ready to revise this opinion when ET finally arrives.

So to return to the questions I set out at the beginning, time cannot be invented - it can only be discovered. Lyell helped us along the route to that discovery – but what a discovery! Its sheer magnitude should make us humble, but it is also frightening. You can almost sympathise with those time deniers who do not wish the human species to be such a grace note on the long symphony of existence. The question of how to use our moment in time has never been so pressing, so time really is of the essence. We humans have probably done more to the planet in our short span of time than anything except the arrival of the meteorite that extinguished the dinosaurs together with so many other animals. Like that meteorite, we seem to be taking out the larger species, and poisoning the seas. I learned recently that the so-called Irish Elk lasted in Siberia for another five thousand years after it had become extinct in Europe. Humankind may have been the final cause. The tiger seems to be going the same way, getting pushed into the same area, and maybe its last redoubt will be where humans rarely go. To use another well-worn phrase, for some it seems that time can indeed run out. However, in the long life of the planet, Lyell was one of the first to appreciate that the lifespan of an individual species counts for little. That includes us. Even if we do our worst, life will go on, the cycles will turn again, mountains built and eroded and leaving their legacy as they did on Hutton’s shore. It’s all a matter of time.

*Department of Palaeontology, The Natural History Museum, London.