The Day the Universe Changed - James Burke [125]
Lyell’s uniformitarianism, an elaboration of Hutton’s argument, was based on the view that only natural causes could be used to explain events, that to a degree the processes at work in the past had to be the same as those of the present, and that the mechanisms were global in nature. So the present geological mechanisms, such as the action of rivers, tides, ocean currents, the movement of icebergs, and so on, were also at work in the past. The past could only be explained scientifically through this method of analogy with modern events.
The Bove Valley, from Lyell’s Principles of Geology. The work is subtitled: ‘An attempt to explain the former changes of the earth’s surface by reference to causes now in operation’.
As for the apparent gaps in the stratigraphic record, Lyell’s view was that there were major groups of organisms which had always been present, while some individual species came and went as their environment changed. Repeated changes in climate, not least variations in temperature, would account for the disappearance of many organisms.
It was with this reference to organisms that Lyell set the scene for revolution. ‘Geology,’he said, ‘is the science which investigates the successive changes which have taken place in the organic and inorganic kingdoms of nature.’In the face of Lyell’s arguments the diluvialists withdrew, forced to admit longer and longer time-scales or invent extra catastrophes. In 1839 Lyell wrote: ‘Conybeare’s memoir is not strong by any means. He admits three deluges before the Noachian! And Buckland adds God knows how many catastrophes besides; so we have driven them out of the Mosaic record fairly!’
In 1831 Lyell’s position as Professor of Geology at King’s College, London, had been confirmed by the Archbishop of Canterbury and the Bishop of London.
The only geological mystery he had not solved was that of the ‘erratics’, which catastrophists still cited in support of their ideas. Erratics were boulders and deposits found in geologically anomalous locations all over England, Scandinavia and the north German plain. How could they have arrived there but by the effects of violent happenings in the past?
Erratics, illustrated by Lyell. These giant fragments were so called because it was considered that they had somehow wandered from their original geological location.
Four years after the last of Lyell’s volumes appeared, in 1837, a Swiss embryologist and palaeontologist, Jean Louis Agassiz, who was later to become Professor of Natural History at Harvard, produced a synthesis of all the most recent views on the problem. The first evidence had been found in 1786 when another Swiss, Horace de Saussure, had climbed Mont Blanc to make a close study of glaciers. Apart from setting the fashion for skiing, Saussure also found fossils on the mountain tops. The only explanation at the time was that they had been placed there as separate and special creations.
Hutton had used Saussure’s findings to argue that boulders could have been moved by glaciers. In 1815, a guide in the Vaud Canton called Perraudin suggested that the glaciers might once have covered much greater areas, perhaps as extensive as the whole of Europe. In 1836 the Director of Mines for Vaud, Jean de Charpentier, together with Agassiz, examined the glaciers of Diablerets and Chamonix, and in the same year another friend of Agassiz, Karl Schimper, suggested a general theory of climatic change in Europe. After extensive work in the crevices of the Aar glacier, Agassiz produced his theory. There had been an ice age at some time in the past which accounted