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Bursting THE LIMITS OF TIME

The University of Chicago Press

Contents

List of illustrations.......................................xiiiAcknowledgments.............................................xixA note on footnotes.........................................xxiiiIntroduction................................................11 Naturalists, philosophers, and others.....................152 Sciences of the earth.....................................593 The theory of the earth...................................1334 Transposing history into the earth........................1815 Problems with fossils.....................................2396 A new science of "geology"?...............................2957 Denizens of a former world................................3498 Geognosy enriched into geohistory.........................4179 The gateway to the deep past..............................47110 Earth's last revolution..................................557Coda: retrospect and prospect...............................639Sources.....................................................653Index.......................................................701

Chapter One

1.1 A SAVANT ON TOP OF THE WORLD

First ascents of Mont Blanc

At eleven o'clock on the morning of 3 August 1787, a party of twenty men climbed wearily through the snow onto the summit of Mont Blanc. All were wearing boots studded with iron nails to improve their grip on the snow, and all held long metal-tipped staffs to help them keep their balance. But one member of the party was distinguished from the rest by his elegant clothing and by the absence of a heavy load on his back. He was clearly a gentleman, one of the others was his personal servant, and the remainder were men from the village of Chamonix far below (Fig. 1.1).

The gentleman was Horace-Bénédict de Saussure (1740–99), a forty-seven-year-old member of a prominent and wealthy family in the city of Geneva, some forty miles to the northwest. He was a "savant"—it would be anachronistic to call him a scientist—who was already famous throughout the scientific world for his Alpine Travels [Voyages dans les Alpes], of which a second handsome volume had been published in Geneva the previous year, with the promise of another still to come. In his Travels he was setting new standards for the scientific description of mountain regions, and providing others with a fine model to emulate. To set foot on what was believed to be the highest point in the Alps, and therefore in Europe, was not only a moment of personal triumph; it was also an event of great symbolic significance for the sciences of nature. It was an even more striking achievement in Saussure's century than the first ascent of Everest was in the twentieth; as remarkable in its time as the first successful expeditions to the north and south poles.

Saussure and his party were not quite the first to stand on the summit of Mont Blanc. He was guided there by Jacques Balmat, a villager from Chamonix, who had reached the peak the previous summer with the local physician, Michel-Gabriel Paccard. Balmat had already been dubbed "le Mont Blanc" for his achievement; and when Saussure wrote an account of his own ascent, he praised the local pair for their courage in climbing to the summit "without even being certain that men could live in the places they aspired to reach". There had in fact been a series of attempts on the mountain during the previous decade, by Saussure himself among others, and some of the villagers had become quite experienced at scaling the slopes of ice and snow. After his first success, Balmat had been commissioned by Saussure to try again in 1787, and he had duly made a second ascent in July, accompanied this time by two other villagers. Saussure had been on his way to Chamonix when they did so, but had not got there in time to go with them. Then the weather had closed in for almost a month, and he had had to wait in patience for another opportunity. When at last the clouds cleared, he had been ready to make it a truly scientific expedition.

Saussure and his party found the ascent arduous. After a relatively simple first day's climb over grassy slopes and easy rocks, they camped 779 toises or fathoms (about 1,500m) above Chamonix. But the second day took them up across a glacier, where they had to negotiate dangerous crevasses—one man fell in, but was saved by being roped to others—and when they stopped for the night Saussure had to assure them that they would not die of cold if they camped on snow. At an altitude of 1,995 toises (about 3,900m) above sea level, even such fit men were exhausted by the effort of digging the snow to make level ground for the tents. Leaving them to such manual labor, Saussure the gentleman contemplated the scene around him: as he recalled later, "no living being was to be seen there, no trace of vegetation; it is a realm of cold and silence". After a fine clear night, during which they were alarmed by the sound of an avalanche, the party toiled slowly up steep slopes of snow, pausing frequently for breath; and two hours after they passed the last outcrop of solid rock they stood on the highest point in Europe (Fig. 1.2).

Science on the summit

Once they were on the summit, a flag was unfurled; but this was no nationalistic exercise, and Saussure did not record what form the flag took. Its purpose was simply to be a sign of their successful arrival, visible from below. His first action on reaching the peak was to look down to Chamonix, where he knew his wife and her sisters would be watching the summit through a telescope. Then he looked out to the horizon, but it was too hazy to see the distant plains of Piedmont (now in northern Italy) to the southeast, or those of France to the northwest beyond Geneva and the hills of the Jura. Still less could he see the Mediterranean some 56 lieues or leagues (about 200km) away, although he later calculated that it was possible in principle to do so, even allowing for the curvature of the earth and for the Apennines rising above the coastline. However, as he recalled, any disappointment in that respect was amply compensated by the spectacular views of the Alps all around him:

What I saw with the greatest clarity was the ensemble of all the high peaks, the arrangement of which I had for so long wanted to understand. I could not believe my eyes, and it seemed to me as if it were a dream ... I was seeing their relationships, their connections and their structure; and a single glance relieved the doubts that years of work had not been able to resolve.

In other words, the view enabled him to improve—at least in his mind's eye—the map of the western Alps that he had published the previous year and to gain a better understanding of the complex physical geography of the environs of Mont Blanc (Fig. 1.3).

While Saussure was enjoying his waking dream, his porters were erecting a tent and a table nearby. Then he set to work with his battery of scientific instruments, for this was no mere sporting trip. The most important of his observations were with the two barometers he had brought: each nearly three feet of glass tubing filled with mercury, carried precariously to the summit on the backs of the porters (see Fig. 1.4). A third...