Mountains of the Mind (10 page)

Ruskin’s intuition that mountains moved was proved unexpectedly correct during the course of the twentieth century, in what is the final significant shift in Western imaginings of the past of mountains. In January 1912, in an incident now legendary among earth scientists, a German called Alfred Wegener (1880–1930) stood up before an audience of eminent geologists in Frankfurt, and told them that the continents moved. Specifically, he explained that the continents, which were composed primarily of granitic rock, ‘drifted’ on top of the denser basalt of the ocean floor, like patches of oil on water. Indeed, 300 million years ago, Wegener informed his increasingly incredulous audience, the landmasses of the world had been united into a single supercontinent, an ur-landmass, which he called Pangaea (meaning ‘all-lands’). Under the divisive power of various geological forces, Pangaea had been riven into many pieces and these
pieces had subsequently drifted apart, ploughing over the basalt to their present positions.

The mountain ranges of the world, Wegener argued, had been created not by the cooling and wrinkling of the earth’s crust – a theory which had come back into vogue at the start of the twentieth century – but by the crash of one drifting continent into another, causing buckling around the impact zone. The low-lying Urals, for example, which nominally separated European Russia from Siberia, were, according to Wegener, the product of an ancient collision between two mobile continents which had occurred so long ago that the effects of mountain building in the impact zone had been largely flattened by erosion.

For proof, said Wegener, just look at the globe. Look at the dispersal of the continents. Move them around a bit and they fit together like a jigsaw puzzle. Slide South America towards Africa and its eastern coast locks into Africa’s western perimeter. Wrap Central America around the Ivory Coast, and North America over the top of Africa and you have half a supercontinent already. The same trick, he pointed out, worked for India’s angled western littoral, which fits snugly against the straight side of the Horn of Africa, just as Madagascar slots neatly back on to the divot on the south-eastern coast of Africa.

Wegener had harder evidence to support his claim. He had spent years working in the extensive fossil archives of the University of Marburg, and had deduced that identical fossil specimens had been found in the rock record at precisely the zones Wegener suggested had once been united: on the west coast of Africa, for example, and the east coast of Brazil the coal deposits and fossils matched. ‘It is just as if we were to refit the torn pieces of a newspaper by matching their edges,’ he wrote, ‘and then check whether the lines of print ran smoothly across. If they do, there is nothing left but to conclude that the pieces were in fact joined in this way.’

Reconstructions of the Map of the World for three periods according to Wegener’s displacement theory. From Alfred Wegener’s
The Origins of Continents and Oceans
, trans. J. A. Skerl, 3rd edn (London: Methuen & Co., 1924).

Wegener was not the first to suggest the interconnectedness of the continents. The sixteenth-century cartographer Ortelius had noticed the jigsaw-puzzle composition of the continents, and had suggested that they were once attached, but had been sundered by drastic floods and earthquakes. He was disbelieved. The endlessly perceptive Francis Bacon mentioned in 1620 in his
Novum Organum
that the continents could fit together ‘as if cut from the same mould’, but
seems to have thought no more about it. And in 1858, a French-American called Antonio Snider-Pelligrini devoted an entire treatise –
Creation and Its Mysteries Revealed
– to showing how the continents had once been united.

But in the mid-nineteenth century there was simply no context for such a radical overhaul of geological theory; no other pieces of knowledge with which the theory itself could fit. A mainstay of nineteenth-century geology was a belief in the existence of enormous land-bridges which had at one point joined the world’s continents, but had since then crumbled into the oceans. These land-bridges explained the existence of the same species on different landmasses, and seemed far more plausible than mobile continents.

In 1912, therefore, Wegener was arguing against the grain of prevailing wisdom: if his theory were correct, it would nullify many of the founding assumptions of nineteenth-century geology. Worse still, Wegener was an intruder, a trespasser on the turf of the geologists. For his main field of research was meteorology – he was a pioneer in weather-balloon study and a specialist in Greenland, where he led several successful, and one fatal, Arctic research expeditions. How could a weatherman presume to dismantle at a single stroke the complex and magnificent edifice of nineteenth-century geology?

The opposition to Wegener’s theory, as to that of Burnet so many years earlier, was immediate and voluble (‘Utter, damned rot!’, said the president of the American Philosophical Society, eloquently). But Wegener, a stoic visionary, remained phlegmatic in the face of early antagonism. In 1915 he published
The Origins of Continents and Oceans
, a careful explanation of his theory, and in its way as apocalyptic a reimagining of the earth’s history as Burnet’s
The Sacred Theory of the Earth
or Hutton’s
The Theory of the Earth
. Between 1915 and 1929 Wegener revised his
Origin
three times to take into account advances in geology, but he was
still ignored by the geological establishment. In 1930 he led another meteorological expedition to Greenland. Three days after his fiftieth birthday he and his team were caught in a severe Arctic blizzard, in which temperatures dropped to −60°F. Wegener became separated from his companions, and froze to death in the private wilderness of a white-out. His body was found by his colleagues when the storm receded. They entombed Wegener inside a mausoleum built of blocks of ice, topped with a twenty-foot iron cross. Within a year, the structure and its contents had disappeared into the interior of the glacier on which it was built – a means of burial that would no doubt have met with Wegener’s approval.

It was not until the advent of the so-called New Geology during the 1960s that it was realized that Wegener had been at least half-right. As advances in bathysphere technology permitted the more systematized exploration of the ocean floor, it was discovered that the continents did indeed move and had indeed spun apart from a vast ur-continent. But the continents weren’t – as Wegener had thought – independent entities drifting over a sea of basalt, like icebergs in water. In fact, the surface of the globe was discovered to be composed of some twenty crustal segments or plates. The continents were simply the portions of the plates which were sufficiently elevated to protrude from the sea.

These plates were named by the New Geologists. There was the African Plate, the Cocos Plate, the North American Plate, the Nazca Plate, the Iran Plate, the Antarctic Plate, the Juan de Fuca Plate, the Australian Plate, the Arabian Plate and the decidedly unfragile China Plates. Driven by convection currents or ‘cells’ within the semi-liquid mantle of the earth, and pulled by their own weight, these plates move around relative to each other. Where their edges meet beneath the ocean, either a mid-ocean ridge or a subduction zone is formed. At mid-ocean ridges the boundaries of two plates are continually
being pushed apart by action in the mantle. Magma rises into the gap, and cools to form sea-floor basalt. Mid-ocean ridges are therefore raised above the surrounding ocean floor, like the seam on a cricket ball. A subduction zone, by contrast, is where the edges of two plates are forced together, and the less buoyant plate slides underneath the other. There, the rock of the subordinate plate is pushed down into the mantle, where it melts and comes bubbling back up in liquid form, causing super-heated wounds in the crust. These subduction zones form the oceanic trenches: the Aleutian Trench, the Java Trench, the Marianas Trench. At the bottom of these trenches – the Marianas Trench is deeper than Mount Everest is high – the atmospheric pressure is so enormous that, were you to materialize at that depth, your body would instantly be compacted to the size of a tin can.

Most of the world’s mountain ranges have been thrown up by the jostling and collision of the continental plates. Thus, for example, the Alps were created when the Adriatic Plate (which carries Italy on its back) was driven into the Eurasian Plate. The oldest mountains are those which are now the lowest, for erosion has had time to reduce them. The blunted, rubbed-down spine of the Urals, for instance, speaks of great age. So too do the rounded forms of the Scottish Cairngorms. Perhaps surprisingly, among the youngest mountains on earth are the Himalaya, which began to form only 65 million years ago, when the Indian Plate motored northwards and smashed slowly into the Eurasian Plate – ducking underneath it and then butting it five-and-a-half miles upwards into the air. Compared to the earth’s venerable ranges, the Himalaya are adolescents, with sharp, punkish ridges instead of the bald and worn-down pates of older ranges.

Like adolescents, too, they are still growing. Everest – which became the world’s highest mountain less than 200,000 years ago – shoots up by a precocious five millimetres or so a year. Give it a million years – the blink of an eye in geological terms – and the
mountain could have almost doubled its height. Except of course that won’t happen, because gravity won’t tolerate such a structure. Something will give: the mountain will collapse under its own weight, or be shaken apart by one of the huge earthquakes which rack the Himalaya every few centuries.

For years now I have gone to the mountains and been astonished by deep time. Once, halfway up the mica-rich peak of Ben Lawers in Scotland on a sunlit day, I found a square chest of sedimentary rock, hinged at its back with an overgrowth of moss and grass. Stepping back and looking at it from the side, I could see it was composed of hundreds of thin layers of grey rock, each one no thicker than a sheet. Each layer, I reckoned, was a paraphrase of 10,000 years – a hundred centuries abbreviated into three millimetres’ depth of rock.

Between two of the grey layers I noticed a thin silvery stratum. I pushed the adze of my walking axe into the rock, and tried to lever the strata apart. The block cracked open, and I managed to get my fingers beneath the heavy top lid of rock. I lifted, and the rock opened. And there, between two layers of grey rock, was a square yard of silver mica, seething brightly in the sunlight – probably the first sunlight to strike it in millions of years. It was like opening up a chest filled to the brim with silver, like opening a book to find a mirror leafed inside it, or like opening a trapdoor to reveal a vault of time so dizzyingly deep that I might have fallen head-first into it.