FAMOUS GEOLOGISTS/Murchison 215 term proposed by Geikie), and suggested that the Moine Schists were in fact formed by the earth movements that gave rise to the folding and faulting, while the repetitions of rock types could be attributed to the S-shaped folding (This suggestion was eventually taken up by Geikie’s own staff, surveying in the 1880s, well after Murchison’s death.) The whole episode illustrates Murchison’s dominating personality and commanding social role towards the end of his career The reasons underlying the Cambrian–Silurian debate have been analyzed by Rudwick (1976) in the following terms At one level, it arose because Murchison’s structural interpretations were not always correct and because he confused the May Hill Sandstone (Wenlock) with the lithologically similar Caradoc Sandstone (Caradoc) Both geologists gained ideas about how to stratigraphy from William Smith (see Famous Geologists: Smith) Smith himself started from the observation of superposed sections of rocks of characteristic structure and lithologies Subsequently, he remarked that each rock suite had its own characteristic fossils, but he saw no reason in principle why one set of fossils should not graduate into another Thus there could, in principle, be overlap between Cambrian and Silurian fossils Murchison started off on a similar basis, but gradually shifted towards thinking that it was fossils that defined a system Once this had happened, and he began to find ‘Silurian’ fossils in Sedgwick’s Cambrian, then annexation of territory ‘naturally’ followed (given that Sedgwick was so slow in getting his ‘Cambrian’ fossils published) It seemed to Murchison that he was dealing with a bona fide system, as it preceded land plants, had few vertebrates, and was apparently distributed widely round the world By contrast, when Sedgwick got round to palaeontological analysis about a decade after his initial fieldwork in North Wales, he thought that the break should, if anywhere, lie between Murchison’s Lower and Upper Silurian; so that for Sedgwick the Cambrian should incorporate Murchison’s Lower Silurian But by then the Lower Silurian was already well established, with its fossils described Rudwick further points out that both geologists were opposed to Lyell’s ‘steady-statism’ (see Famous Geologists: Lyell) They both believed that life originated at some point in the past, and Murchison wished ‘his’ system to be the one that contained the first evidences of life with hard-bodied remains Hence he sought to cannibalize Murchison’s Cambrian When Barrande in Bohemia found a ‘Primordial’ fauna below Murchison’s Lower Silurian (palaeontologically defined), it could have served as palaeontological basis for a Cambrian System But Murchison declined to follow this path, and did not practise what he preached in the matter of the Cambrian Like many geologists of his day, Murchison gave considerable attention to the problem of the superficial ‘drift’ deposits that blanket much of Europe, and which he saw in abundance in Scandinavia, Russia, Britain, and elsewhere In the early nineteenth century, such materials were commonly ascribed to the Noachian Flood, or later to catastrophic floods but not necessarily universal or of divine origin In the 1840s, there were two further contending theories: that of climatic change producing an Ice Age, with land ice as the agent for the emplacement of the ‘drift’, as advocated by Louis Agassiz (see Famous Geologists: Agassiz); and various versions of ‘glacial submergence’, with cooling and changes of sea-level relative to the land such that floating icebergs could carry detritus and deposit mud and ‘erratic’ boulders, as envisaged by Darwin and Lyell The ‘flood theory’ received some theoretical support from the Cambridge mathematician and geologist, William Hopkins, who advocate the idea of ‘waves of translation’ A sudden uplift of the sea-floor might, it was suggested, produce not only waves at the ocean surface, but also wholesale lateral movement of masses of water, capable of transporting (‘translating’) large boulders and finer debris It was Hopkins’ theory that Murchison favoured, in part because it was seemingly in accord with the evidences familiar to him in the Alps and elsewhere of huge earth movements, foldings, faulting, and even inversions (Murchison had seen evidence of stratigraphic inversion in the Glarus Canton, Switzerland, when he visited the area in 1848, but subsequently disregarded it in his thoughts about the north-west Highlands of Scotland.) He accepted that retreating glaciers left moraine material in the Alpine regions, and was happy with the idea of icebergs transporting drift material But for long he could not accept landice as being responsible for the huge tracts of drift on land of low relief that he saw in Russia Besides, the evidence of striations did not seem to accord with the land-ice theory For example, in the area of the Gulf of Bothnia he saw scratch-marks directed southeastwards, from an area of Sweden of low altitude He did not imagine that glaciers could have come from further north, from the mountains of Arctic Sweden Nor could he imagine that land-ice could on occasions travel uphill, transporting marine shells to hill tops It was only in 1862 that Murchison conceded to Agassiz’s land-ice theory Murchison was one of the heroes of the heroic age of geology His contributions to stratigraphy, and the broadening of geological knowledge generally, were immense He was extraordinarily energetic, and generally amiable Other than Lyell, he was far