Annals of the Former World

by John McPhee

  Clearly, if you were going to change a scene, and change it again and again, you would need adequate time. To make the rock of that lower formation and then tilt it up and wear it down and deposit sediment on it to form the rock above would require an immense quantity of time, an amount that was expressed in the clean, sharp line that divided the formations—the angular unconformity itself. You could place a finger on that line and touch forty million years. The lower formation, called Tonka, formed in middle Mississippian time. The upper formation, called Strathearn, was deposited forty million years afterward, in late Pennsylvanian time. Cambrian, Ordovician, Silurian, Devonian, Mississippian, Pennsylvanian, Permian, Triassic, Jurassic, Cretaceous, Paleocene, Eocene, Oligocene, Miocene, Pliocene, Pleistocene … In the long roll call of the geologic systems and series, those formations—those discrete depositional events, those forty million years—were next-door neighbors on the scale of time. The rock of the lower half of that hill dated to three hundred and forty million years ago, in the Mississippian, and the rock above the unconformity dated to three hundred million years ago, in the Pennsylvanian. If you were to lift your arms and spread them wide and hold them straight out to either side and think of the distance from fingertips to fingertips as representing the earth’s entire history, then you would have all the principal events in that hillside in the middle of the palm of one hand.

  It was an angular unconformity in Scotland—exposed in a riverbank at Jedburgh, near the border, exposed as well in a wavescoured headland where the Lammermuir Hills intersect the North Sea—that helped to bring the history of the earth, as people had understood it, out of theological metaphor and into the perspectives of actual time. This happened toward the end of the eighteenth century, signalling a revolution that would be quieter, slower, and of another order than the ones that were contemporary in America and France. According to conventional wisdom at the time, the earth was between five thousand and six thousand years old. An Irish archbishop (James Ussher), counting generations in his favorite book, figured this out in the century before. Ussher actually dated the earth, saying that it was created in 4004 B.C., “upon the entrance of the night preceding the twenty-third day of October.”

  It was also conventional wisdom toward the end of the eighteenth century that sedimentary rock had been laid down in Noah’s Flood. Marine fossils in mountains were creatures that had got there during the Flood. To be sure, not everyone had always believed this. Leonardo, for example, had noticed fossil clams in the Apennines and, taking into account the distance to the Adriatic Sea, had said, in effect, that it must have been a talented clam that could travel a hundred miles in forty days. Herodotus had seen the Nile Delta—and he had seen in its accumulation unguessable millennia. G. L. L. de Buffon, in 1749 (the year of Tom Jones), began publishing his forty-four-volume Histoire Naturelle, in which he said that the earth had emerged hot from the sun seventy-five thousand years before. There had been, in short, assorted versions of the Big Picture. But the scientific hypothesis that overwhelmingly prevailed at the time of Bunker Hill was neptunism—the aqueous origins of the visible world. Neptunism had become a systematized physiognomy of the earth, carried forward to the nth degree by a German academic mineralogist who published very little but whose teaching was so renowned that his interpretation of the earth was taught as received fact at Oxford and Cambridge, Turin and Leyden, Harvard, Princeton, and Yale. His name was Abraham Gottlob Werner. He taught at Freiberg Mining Academy. He had never been outside Saxony. Extrapolation was his means of world travel. He believed in “universal formations.” The rock of Saxony was, beyond a doubt, by extension the rock of Peru. He believed that rock of every kind—all of what is now classified as igneous, sedimentary, and metamorphic—had precipitated out of solution in a globe-engulfing sea. Granite and serpentine, schist and gneiss had precipitated first and were thus “primitive” rocks, the cores and summits of mountains. “Transitional” rocks (slate, for example) had been deposited underwater on high mountain slopes in tilting beds. As the great sea fell and the mountains dried in the sun, “secondary” rocks (sandstone, coal, basalt, and more) were deposited flat in waters above the piedmont. And while the sea kept withdrawing, “alluvial” rock—the “tertiary,” as it was sometimes called—was established on what now are coastal plains. That was the earth’s surface as it was formed and had remained. There was no hint of where the water went. Werner was gifted with such rhetorical grace that he could successfully omit such details. He could gesture toward the Saxon hills—toward great pyramids of basalt that held castles in the air—and say, without immediate fear of contradiction, “I hold that no basalt is volcanic.” He could dismiss volcanism itself as the surface effect of spontaneous combustion of coal. His ideas may now seem risible in direct proportion to their amazing circulation, but that is characteristic more often than not of the lurching progress of science. Those who laugh loudest laugh next. And some contemporary geologists discern in Werner the lineal antecedence of what has come to be known as black-box geology—people in white coats spending summer days in basements watching million-dollar consoles that flash like northern lights—for Werner’s “first sketch of a classification of rocks shows by its meagreness how slender at that time was his practical acquaintance with rocks in the field.” The words are Sir Archibald Geikie’s, and they appeared in 1905 in a book called The Founders of Geology. Geikie, director general of the Geological Survey of Great Britain and Ireland, was an accomplished geologist who seems to have dipped in ink the sharp end of his hammer. In summary, he said of Werner, “Through the loyal devotion of his pupils, he was elevated even in his lifetime into the position of a kind of scientific pope, whose decisions were final on any subject regarding which he chose to pronounce them … . Tracing in the arrangement of the rocks of the earth’s crust the history of an original oceanic envelope, finding in the masses of granite, gneiss, and mica-schist the earliest precipitations from that ocean, and recognising the successive alterations in the constitution of the water as witnessed by the series of geological formations, Werner launched upon the world a bold conception which might well fascinate many a listener to whom the laws of chemistry and physics, even as then understood, were but little known.” Moreover, Werner’s earth was compatible with Genesis and was thus not unpleasing to the Pope himself. When Werner’s pupils, as they spread through the world, encountered reasoning that ran contrary to Werner’s, pictures that failed to resemble his picture, they described all these heresies as “visionary fabrics”—including James Hutton’s Theory of the Earth; or, an Investigation of the Laws Observable in the Composition, Dissolution, and Restoration of Land Upon the Globe, which was first presented before the Royal Society of Edinburgh at its March and April meetings in 1785.

  Hutton was a medical doctor who gave up medicine when he was twenty-four and became a farmer who at the age of forty-two retired from the farm. Wherever he had been, he had found himself drawn to riverbeds and cutbanks, ditches and borrow pits, coastal outcrops and upland cliffs; and if he saw black shining cherts in the white chalks of Norfolk, fossil clams in the Cheviot Hills, he wondered why they were there. He had become preoccupied with the operations of the earth, and he was beginning to discern a gradual and repetitive process measured out in dynamic cycles. Instead of attempting to imagine how the earth may have appeared at its vague and unobservable beginning, Hutton thought about the earth as it was; and what he did permit his imagination to do was to work its way from the present moment backward and forward through time. By studying rock as it existed, he thought he could see what it had once been and what it might become. He moved to Edinburgh, with its geologically dramatic setting, and lived below Arthur’s Seat and the Salisbury Crags, remnants of what had once been molten rock. It was impossible to accept those battlement hills precipitating in a sea. Hutton had a small fortune, and did not have to distract himself for food. He increased his comfort when he invested in a company that made sal ammoniac from collected soot of the city
. He performed experiments—in chemistry, mainly. He extracted table salt from a zeolite. But for the most part—over something like fifteen years—he concentrated his daily study on the building of his theory.

  Growing barley on his farm in Berwickshire, he had perceived slow destruction watching streams carry soil to the sea. It occurred to him that if streams were to do that through enough time, there would be no land on which to farm. So there must be in the world a source of new soil. It would come from above—that was to say, from high terrain—and be made by rain and frost slowly reducing mountains, which in stages would be ground down from boulders to cobbles to pebbles to sand to silt to mud by a ridge-to-ocean system of dendritic streams. Rivers would carry their burden to the sea, but along the way they would set it down, as fertile plains. The Amazon had brought off the Andes half a continent of plains. Rivers, especially in flood, again and again would pick up the load, to give it up ultimately in depths of still water. There, in layers, the mud, silt, sand, and pebbles would pile up until they reached a depth where heat and pressure could cause them to become consolidated, fused, indurated, lithified—rock. The story could hardly end there. If it did, then the surface of the earth would have long since worn smooth and be some sort of global swamp. “Old continents are wearing away,” he decided, “and new continents forming in the bottom of the sea.” There were fossil marine creatures in high places. They had not got up there in a flood. Something had lifted the rock out of the sea and folded it up as mountains. One had only to ponder volcanoes and hot springs to sense that there was a great deal of heat within the earth—much exceeding what could ever be produced by an odd seam of spontaneously burning coal—and that not only could high heat soften up rock and change it into other forms of rock, it could apparently move whole regions of the crustal package and bend them and break them and elevate them far above the sea.

  Granite also seemed to Hutton to be a product of great heat and in no sense a precipitate that somehow grew in water. Granite was not, in a sequential sense, primitive rock. It appeared to him to have come bursting upward in a hot fluid state to lift the country above it and to squirt itself thick and thin into preexisting formations. No one had so much as imagined this before. Basalt was no precipitate, either. In Hutton’s description, it had once been molten, exhibiting “the liquefying power and expansive force of subterranean fire.” Hutton’s insight was phenomenal but not infallible. He saw marble as having once been lava, when in fact it is limestone cooked under pressure in place.

  Item by item, as the picture coalesced, Hutton did not keep it entirely to himself. He routinely spent his evenings in conversation with friends, among them Joseph Black, the chemist, whose responses may have served as a sort of fixed foot to the wide-swinging arcs of Hutton’s speculations—about the probable effect on certain materials of varying ratios of temperature and pressure, about the story of the forming of rock. Hutton was an impulsive, highly creative thinker. Black was deliberate and critical. Black had a judgmental look, a lean and somber look. Hutton had dark eyes that flashed with humor under a far-gone hairline and an oolitic forehead full of stored information. Black is regarded as the discoverer of carbon dioxide. He is one of the great figures in the history of chemistry. Hutton and Black were among the founders of an institution called the Oyster Club, where they whiled away an evening a week with their preferred companions—Adam Smith, David Hume, John Playfair, John Clerk, Robert Adam, Adam Ferguson, and, when they were in town, visitors from near and far such as James Watt and Benjamin Franklin. Franklin called these people “a set of as truly great men … as have ever appeared in any Age or Country.” The period has since been described as the Scottish Enlightenment, but for the moment it was only described as the Oyster Club. Hutton, who drank nothing, was a veritable cup running over with enthusiasm for the achievements of his friends. When Watt came to town to report distinct progress with his steam engine, Hutton reacted with so much pleasure that one might have thought he was building the thing himself. While the others busied themselves with their economics, their architecture, art, mathematics, and physics, their naval tactics and ranging philosophies, Hutton shared with them the developing fragments of his picture of the earth, which, in years to come, would gradually remove the human world from a specious position in time in much the way that Copernicus had removed us from a specious position in the universe.

  A century after Hutton, a historian would note that “the direct antagonism between science and theology which appeared in Catholicism at the time of the discoveries of Copernicus and Galileo was not seriously felt in Protestantism till geologists began to impugn the Mosaic account of the creation.” The date of the effective beginning of the antagonism was the seventh of March, 1785, when Hutton’s theory was addressed to the Royal Society in a reading that in all likelihood began with these words: “The purpose of this Dissertation is to form some estimate with regard to the time the globe of this Earth has existed.” The presentation was more or less off the cuff, and ten years would pass before the theory would appear (at great length) in book form. Meanwhile, the Society required that Hutton get together a synopsis of what was read on March 7th and finished on April 4, 1785. The present quotations are from that abstract.

  We find reason to conclude, 1st, That the land on which we rest is not simple and original, but that it is a composition, and had been formed by the operation of second causes. 2dly, That before the present land was made there had subsisted a world composed of sea and land, in which were tides and currents, with such operations at the bottom of the sea as now take place. And, Lastly, That while the present land was forming at the bottom of the ocean, the former land maintained plants and animals … in a similar manner as it is at present. Hence we are led to conclude that the greater part of our land, if not the whole, had been produced by operations natural to this globe; but that in order to make this land a permanent body resisting the operations of the waters two things had been required; 1st, The consolidation of masses formed by collections of loose or incoherent materials; 2dly, The elevation of those consolidated masses from the bottom of the sea, the place where they were collected, to the stations in which they now remain above the level of the ocean … .

  Having found strata consolidated with every species of substance, it is concluded that strata in general have not been consolidated by means of aqueous solution … .

  It is supposed that the same power of extreme heat by which every different mineral substance had been brought into a melted state might be capable of producing an expansive force sufficient for elevating the land from the bottom of the ocean to the place it now occupies above the surface of the sea … .

  A theory is thus formed with regard to a mineral system. In this system, hard and solid bodies are to be formed from soft bodies, from loose or incoherent materials, collected together at the bottom of the sea; and the bottom of the ocean is to be made to change its place … to be formed into land … .

  Having thus ascertained a regular system in which the present land of the globe had been first formed at the bottom of the ocean and then raised above the surface of the sea, a question naturally occurs with regard to time; what had been the space of time necessary for accomplishing this great work? …

  We shall be warranted in drawing the following conclusions; 1st. That it had required an indefinite space of time to have produced the land which now appears; 2dly, That an equal space had been employed upon the construction of that former land from whence the materials of the present came; Lastly, That there is presently laying at the bottom of the ocean the foundation of future land … .

  As things appear from the perspective of the twentieth century, James Hutton in those readings became the founder of modern geology. As things appeared to Hutton at the time, he had constructed a theory that to him made eminent sense, he had put himself on the line by agreeing to confide it to the world at large, he had provoked not a few hornets into flight, and now—like the experimental physicists who wou
ld one day go off to check on Einstein by photographing the edges of solar eclipses—he had best do some additional travelling to see if he was right. As he would express all this in a chapter heading when he ultimately wrote his book, he needed to see his “Theory confirmed from Observations made on purpose to elucidate the Subject.” He went to Galloway. He went to Banffshire. He went to Saltcoats, Skelmorlie, Rumbling Bridge. He went to the Isle of Arran, the Isle of Man, Inchkeith Island in the Firth of Forth. His friend John Clerk sometimes went with him and made line drawings and watercolors of scenes that arrested Hutton’s attention. In 1968, a John Clerk with a name too old for Roman numerals found a leather portfolio at his Midlothian estate containing seventy of those drawings, among them some cross sections of mountains with granite cores. Since it was Hutton’s idea that granite was not a “primary” rock but something that had come up into Scotland from below, molten, to intrude itself into the existing schist, there ought to be pieces of schist embedded here and there in the granite. There were. “We may now conclude,” Hutton wrote later, “that without seeing granite actually in a fluid state we have every demonstration possible of this fact; that is to say, of granite having been forced to flow in a state of fusion among the strata broken by a subterraneous force, and distorted in every manner and degree.”