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FAMOUS GEOLOGISTS | Sedgwick
216 FAMOUS GEOLOGISTS/Sedgwick
the most influential British geologist of his day. But he exercised that influence through the hand of administrative power as much as by reasoned argument. He was a conservative in both politics and geological theory. Even his prote´ ge´ Geikie, who owed him so much, concluded that Murchison ‘‘was not gifted with the philosophical spirit which evolves broad laws and principles in science. He had hardly any imaginative power. He wanted . . . the genius for dealing with questions of theory . . .’’ Possibly things would have been different if Murchison had received a university, rather than a military, education.
See Also Famous Geologists: Agassiz; Darwin; Lyell; Sedgwick; Smith. History of Geology From 1780 To 1835. History of Geology From 1835 To 1900. Palaeozoic: Ordovician; Silurian; Devonian; Carboniferous.
Further Reading Geikie A (1875) Life of Sir Roderick I. Murchison. . . Based on his Journals and Letters With Notices of his
Scientific Contemporaries and a Sketch of the Rise and Growth of Palaeozoic Geology. London: John Murray (reprinted in facsimile by Gregg International Publishers Ltd, 1972). Oldroyd DR (1990) The Highlands Controversy: Constructing Geological Knowledge through Fieldwork in Nineteenth-Century Britain. Chicago and London: Chicago University Press. Rudwick MJS (1972) Levels of Disagreement in the Sedgwick–Murchison Controversy. Journal of the Geological Society 132: 373–375. Rudwick MJS (1985) The Great Devonian Controversy: The Shaping of Scientific Knowledge among Gentlemanly Specialists. Chicago and London: Chicago University Press. Secord JE (1986) Controversy in Victorian Geology: The Cambrian–Silurian Dispute. Princeton: Princeton University Press. Stafford RA (1989) Scientist of Empire: Sir Roderick Murchison, Scientific Exploration and Victorian Imperialism. Cambridge, New York, Port Chester, Melbourne and Sydney: Cambridge University Press. Thackray JC (1976) The Murchison–Sedgwick Controversy. Journal of the Geological Society 132: 367–372.
Sedgwick D R Oldroyd, University of New South Wales, Sydney, Australia ß 2005, Elsevier Ltd. All Rights Reserved.
Introduction Adam Sedgwick (Figure 1) was born in 1785 in the village of Dent in the Yorkshire Dales, northern England, son of the local vicar and third of a family of seven. He died as a Fellow of Trinity College and Professor of Geology at Cambridge in 1873. He attended Sedbergh School near Dent, and with help from a notable local amateur mathematician, John Dawson of Garsdale, obtained a scholarship to Trinity, where he studied mathematics. He was named 5th Wrangler (fifth in the list of first-class honours students) in 1808. Following further examination, Sedgwick obtained a College Fellowship in 1810 and taught undergraduate mathematics. He was ordained in 1817. On becoming a permanent member of college, Sedgwick also committed himself to bachelorhood. During his life as a geologist, he proved to be extremely energetic in the field, covering large distances in a day. In Cambridge, he was quite often indisposed, but his chronic health
problems apparently disappeared once he got into fieldwork. Though a gifted mathematician, Sedgwick did not make a career in that discipline. From fragmentary autobiographical notes, he evidently had some geological interests from an early age, and he ‘geologized’ on the Continent in 1816. Also, he was ‘introduced’ to the Geological Society of London in 1818. Even so, it is surprising that his scientific accomplishments were thought sufficient to secure the Cambridge chair in geology that year. He was elected Fellow of the Royal Society in 1821, John Herschel heading the list of those who nominated him. Sedgwick was President of the Geological Society in 1829–31, and President of the British Association when it met in Cambridge in 1833.
Geological Work On obtaining his chair, Sedgwick threw himself into geology. He started his annual fieldwork in southern England, then worked his way northwards to Northumberland, and in the years 1822–24 he made the first systematic survey of the Lake District. He obtained topographic maps of the region, ‘recognized’ certain rock units, and systematically covered
FAMOUS GEOLOGISTS/Sedgwick 217
Figure 1 Portrait of Adam Sedgwick (1785–1873); the original is in the Sedgwick Museum, Cambridge. Copyright: The Sedgwick Museum of Earth Sciences.
the region over three seasons, colouring in his maps according to his selected lithological units. Sedgwick did not look much for fossils, but measured strata and cleavage dips and the alignments of beds, folds, faults, joints, and cleavage planes. Faults sometimes could be seen on the ground. At other times, they became apparent when the different rock types were coloured onto the maps. Sedgwick’s labour and energy were immense. Armed with hammer, acid bottle, map, compass, clinometer, and notebooks, Sedgwick tried to determine the structure of that complicated region. Trained in mathematics, the neophyte geologist was trying to ascertain whether the strata displayed any regular geometric pattern. They hardly did, but when Sedgwick published his work he sought to subsume it under the theory of Le´ once E´ lie de Beaumont, according to which, as the Earth cooled and contracted, it supposedly formed a regular fold pattern in its crust, with mountain ranges of similar age having similar alignments. The theory never exerted much influence in Britain, and Sedgwick soon gave up the idea; but the fact that he sought to deploy the French theory suggests that he was interested in a geometrical (mathematical) theory of the earth. This was consistent with the Cambridge tradition, which found expression in the activities of the Cambridge Philosophical Society, which Sedgwick helped found in 1819. He wanted a quantitative geology, with mathematically formulated laws. However, his later Lakeland work (assisted by amateur collectors) used fossils, and by the end of his career, he had worked out a stratigraphic order for the sedimentary rocks compatible with that later developed on biostratigraphic principles. Sedgwick also recognized the
rocks of central Lakeland for what they were: the relics of ancient volcanoes. He referred to waterdeposited volcanic ash deposits as volcanic mud. From his Lakeland work, Sedgwick came to understand (and publish) the distinction between bedding and cleavage, but the distinction was acquired from the local amateur Jonathan Otley, who probably got it from quarrymen. Sedgwick’s Lakeland mapping revealed the existence of large tear-faults in some of the strata, and the eastern boundary of the region was marked by a huge normal fault. Hence, he suggested that the area had been affected by great earth movements. Using terminology proposed in the 1830s by his Trinity colleague, William Whewell, Sedgwick was a ‘catastrophist’. Sedgwick soon met Roderick Murchison (see Famous Geologists: Murchison), who wanted someone to show him how to make sense of ancient rocks in mountainous regions, and together they undertook a lengthy reconnaissance journey round the north coast of Scotland in 1827, unfortunately correlating the eastern and western sandstones of northern Scotland (now regarded as Devonian and Precambrian, respectively). In 1829, they made an extensive tour of the Continent, meeting European professors and travelling to Germany, Bohemia, Hungary, Austria, Switzerland, and Italy. This greatly extended Sedgwick’s experience, especially in the ‘‘focus of Wernerian geology,’’ southern Germany, which he found to be ‘‘the most decidedly volcanic secondary country I ever saw’’. He observed granite veins and inclined or even overturned Secondary rocks (a term used in the nineteenth century as a synonym for the German term Floetz; later for the strata ranging from Silurian to Cretaceous; and later restricted to the Mesozoic Era). This demolished his earlier adherence to Neptunism and he publicly repudiated the doctrine in 1831. Observations in Italy clearly suggested uplift, which was not part of the Wernerian repertoire. On the other hand, Sedgwick was inclined to ascribe the movement of (glacial) erratic boulders to the action of catastrophic floods, but some Swiss deposits could have been emplaced by the bursting of lake barriers. He rejected the idea that ‘diluvium’ was all deposited in the Noachian Flood, but was critical of Charles Lyell’s belief that conditions on Earth were essentially similar through time (see Famous Geologists: Lyell). In the 1830s, Sedgwick collaborated with Murchison in Wales, trying to bring order to the strata there. The strata in the mountains of Snowdonia seemed to have analogy with those of the lakes. Sedgwick tackled them, working on somewhat similar lines, and making a traverse north-west to southeast across Snowdonia in 1832. He unravelled the
218 FAMOUS GEOLOGISTS/Sedgwick
structure to some extent, and although the rocks seemed to have few fossils, the Cambrian System was introduced, largely on the basis of Sedgwick’s work. Murchison, starting in the Welsh border region in gentler country with fossiliferous rocks, had an easier time and revealed what appeared to be a new system with its characteristic fossils, dubbed the Silurian. However, the line of boundary between the two systems was not established at the outset of the investigations in 1834, with the result that a bitter feud subsequently broke out between Sedgwick and Murchison, with the former trying to extend ‘his’ system upwards, the latter endeavouring to expand ‘his’ downwards, eventually to the very lowest fossiliferous rocks. (The issues were very complex; it was not until after the protagonists’ deaths that the issues were resolved, by Charles Lapworth, who, in 1879, proposed the Ordovician System to occupy the disputed territory between the Cambrian and Silurian. (see Palaeozoic: Ordovician) Sedgwick had complained, with reason, that materials he had sent to the Geological Society were changed so as to accord with Murchison’s views, without Sedgwick’s knowledge or consent. The situation grew so bad between the two that after 1853, the Geological Society declined to accept further papers by the protagonists of Siluria or Cambria. Sedgwick felt grievously ill treated and snubbed by the Society. The battle became transferred to the forum of the British Association, but after 1854, Sedgwick withdrew from that body also, so far as the Cambrian and Silurian were concerned, and continued the battle from Cambridge and in the pages of the Philosophical Magazine. Some of the stratigraphic formations and their classifications are shown in Figure 2. It should be noted that the rocks that Murchison allowed to be Cambrian in 1859 were the unfossiliferous Longmynd rocks, later classified as Precambrian. (Murchison also allowed Sedgwick the unfossiliferous Torridonian Sandstone in Scotland, also now regarded as Precambrian.) Initially, Murchison won the battle, partly because he had better fossil evidence, and placed full reliance on it. Also, he had strong influence in the Geological Society and became Director of the Geological Survey in 1855, and his classifications were used by the survey officers. Sedgwick had fewer allies, mostly at Cambridge. For the rocks he was dealing with, he had to rely on structural understanding and lithologically based mapping to a greater extent than did Murchison. (Graptolites were not regularly used for stratigraphic correlation in the mid-nineteenth century.) However, Sedgwick succeeded in showing, on palaeontological grounds, that the claimed unity of Murchison’s Silurian System was flawed. In 1852,
Sedgwick and his assistant Frederick McCoy found that one of Murchison’s Silurian formations, the Caradoc, had rocks containing two distinct faunas, as shown by the palaeontological determinations of McCoy and John Salter. There had been erroneous correlations; the same term, ‘Caradoc Sandstone’, had been applied to different series of rocks; and there should be an unconformity within the Caradoc, as Murchison then understood it. Sedgwick proposed the division of Murchison’s Caradoc into the Caradoc Sandstone, containing fossils such as Trinucleus, and an upper May Hill Sandstone, containing Pentamerus species. This eventually turned the tide against his Silurian being regarded as a coherent system. The Survey sought to retrieve the situation by adopting the terminology ‘May Hill Sandstone Llandovery’ rocks, regarding them as a kind of passage or ‘Intermediate Series’ between the Upper and Lower Silurian. There were repercussions, too, for the interpretation of Murchison’s Llandeilo. This battle was fought with extreme vehemence. Both geologists attached their names and reputations to ‘their’ system. The battle seemed to exemplify the height of the colonial era, with Sedgwick and Murchison trying to extend their empires. Murchison was popularly called the ‘King of Siluria’. Both men tried to rewrite history in their historical accounts of the events. In Sedgwick’s case, this may have been partly due to failing memory. Earlier, there had been a bitter controversy in Devonshire, where, while still friends, Sedgwick and Murchison began to unravel the structure and stratigraphy of the area, in the process becoming involved in controversy with Henry De La Beche, the first Director of the Geological Survey. From this acrimonious debate emerged the concept of the Devonian System. The so-called Old Red Sandstone was the unit well known in eastern Scotland as lying unconformably over Silurian strata. It was mapped by William Smith as ‘Red and Dunstone’. He placed it below the Coal Measures and below a limestone that cropped out in Derbyshire and elsewhere. In Devonshire, there occurred rocks with plant remains that appeared to De la Beche to belong to the old Transition/Greywacke series (Cambrian or Silurian rocks). In Murchison’s opinion, however, the plant-bearing rocks could not be so old: they must be from the Coal Measures. But he had not then been to Devon to see the rocks for himself. Murchison then combined forces with Sedgwick to combat De la Beche’s interpretation. It was an issue of more than academic significance because it bore on the question of the possible extent of coal-bearing rocks. The plant-bearing rocks overlay contorted rocks of ancient appearance, but these contained corals
FAMOUS GEOLOGISTS/Sedgwick 219
Figure 2 Classification of British Lower Palaeozoic Rocks. Reproduced from Secord JA (1986) Controversy in Victorian Geology: The Cambrian– Siurian Dispute, p. 287. Copyright ß1986 by P.U. Press. Reprinted by permission of Princeton University Press.
different from those in the Silurian. In the opinion of the coral expert William Lonsdale, the corals were intermediate between Silurian and Coal Measure types. Thus, the Devon rocks might be situated between the Silurian and the Carboniferous. So, in 1839, Sedgwick and Murchison proposed the Devonian System, being one that had different facies in different localities. Here the palaeontological evidence of corals was taken to outweigh the uncertain stratigraphic reliability of plant fossils and the structural arguments advanced by De la Beche. The issues were debated with considerable rancour and again illustrate the character of stratigraphic controversies in the nineteenth century. But this time, Sedgwick and Murchison were on the same side and the debate
never got quite so out of hand as did the Silurian/ Cambrian contest.
Sedgwick as a Teacher; Other Activities, Beliefs, and Character At Cambridge, Sedgwick gave an annual course of lectures and built up the university’s geological collections, partly from his own collected specimens, but also by donations and purchases. His summer fieldwork was done at his own expense. Partly for this reason, he took a ‘second job’ in 1834, as a canon at Norwich Cathedral. This might have been a sinecure, but Sedgwick took his responsibilities seriously, and resided in Norwich for several months each year, also
s9000
p0065
220 FAMOUS GEOLOGISTS/Sedgwick
encouraging the development of a museum in the city and giving geological lectures. Sedgwick was a strong supporter of amateur science and assisted the natural history society in Kendal, near Dent. Sedgwick was a renowned orator – or preacher and lecturer. Science lectures were not a required part of the Cambridge curriculum when he gave his first course in 1819, but he attracted many students and dons to his lectures. His course was repeated until 1859, when he was 74. He spoke extempore about geological principles and his recent fieldwork, rather than about unnecessary minutiae. His lectures, utilizing specimens and maps and diagrams to explain his ideas, were popular, and he also led groups on horseback on field excursions round Cambridge. On a famous occasion at the British Association meeting at Newcastle in 1838, he spoke in the morning at Tynemouth beach to a group attending the meeting; and by the afternoon he had attracted a crowd of thousands, expounding the relationships (as he saw them) between geology, political economy, natural theology, and patriotism, reportedly drawing tears of emotion from some auditors. As John Herschel described it, Sedgwick led them on from the scene around them to the wonders of the coal-country below them, thence to the economy of a coal-field, then to their relations to the coal-owners and capitalists, then to the great principles of morality and happiness, and last to their relation to God and their own future prospects. (Clarke and Hughes (1890).)
In this can be seen the relationship between Sedgwick’s science, social, religious, and political philosophy. Implausibly, he supposed that Britain had been specially favoured by God for its place in the world, with its deposits of coal, limestone, and iron ore. Sedgwick was, then, devoutly religious, and a preacher as well as a teacher. From a relatively obscure Anglican background, he rose to be a Cambridge Professor and Vice-Master of Trinity, and one of the leaders of the heroic age of geology. He even met with Prince Albert (whose election to the Chancellorship of the University he promoted) to discuss reforms at Cambridge, and many of Sedgwick’s suggestions were implemented. Though generally amiable, greatly liked and admired, and able to communicate with the full range of society, from quarrymen, to famous writers such as William Wordsworth or Walter Scott, to Royalty, he was uncompromising and dogmatic. He favoured Catholic emancipation, but having become an establishment figure, he did not wish to see the regular order of things upset by scientific theories that seemed to him subversive, or at odds with orthodox Anglican theology. For such
reasons, he was bitterly and publicly opposed to the transmutationist ideas expressed in 1844 by Robert Chambers in his Vestiges of the Natural History of Creation, and was privately grieved by Charles Darwin’s ideas in The Origin of Species (see Famous Geologists: Darwin). He also rejected the land–ice theory of Louis Agassiz (see Famous Geologists: Agassiz).
See Also Famous Geologists: Agassiz; Darwin; Lyell; Murchison; Smith. History of Geology From 1780 To 1835. History of Geology From 1835 To 1900. Palaeozoic: Cambrian; Ordovician; Silurian.
Further Reading Clark JW and Hughes TMcK (1890) The Life and Letters of the Reverend Adam Sedgwick, LL.D., D.C.L., F.R.S., Fellow of Trinity College, Cambridge, Prebendary of Norwich, Woodwardian Professor of Geology, 1818–1873. Cambridge: Cambridge University Press. Oldroyd DR (2002) Adam Sedgwick: a confident mind in turmoil. In: Harman P and Mitton S (eds.) Cambridge Scientific Minds, pp. 64–78. Cambridge: Cambridge University Press. Oldroyd DR (2002) Earth, Water, Ice and Fire: Two Hundred Years of Geological Research in the English Lake District. London: The Geological Society. Rudwick MJS (1972) Levels of disagreement in the Sedgwick–Murchison controversy. Journal of the Geological Society 132: 373–375. Rudwick MJS (1985) The Great Devonian Controversy: The Shaping of Scientific Knowledge among Gentlemanly Specialists. Chicago and London: Chicago University Press. Rudwick MJS (1988) A year in the life of Adam Sedgwick and company, geologists. Archives of Natural History 15: 243–268. Secord JA (1986) Controversy in Victorian Geology: The Cambrian–Silurian Dispute. Princeton and Guildford: Princeton University Press. Sedgwick A and Murchison RI (1835/36) On the Silurian and Cambrian Systems, exhibiting the order in which the older sedimentary strata succeed each other in England and Wales. Report of the Fifth Meeting of the British Association for the Advancement of Science held at Dublin in 1835, pp. 59–61. London: John Murray. Smith C (1985) Geology and mathematicians: the rise of physical geology. In: Harman PM (ed.) Wranglers and Physicists: Studies on Cambridge Physics in the Nineteenth Century, pp. 49–83. Manchester: Manchester University Press. Speakman C (1969) Adam Sedgwick Geologist and Dalesman, 1785–1873: A Biography in Twelve Themes. Broad Oak, London, and Cambridge: The Broad Oak Press Ltd.
the most influential British geologist of his day. But he exercised that influence through the hand of administrative power as much as by reasoned argument. He was a conservative in both politics and geological theory. Even his prote´ ge´ Geikie, who owed him so much, concluded that Murchison ‘‘was not gifted with the philosophical spirit which evolves broad laws and principles in science. He had hardly any imaginative power. He wanted . . . the genius for dealing with questions of theory . . .’’ Possibly things would have been different if Murchison had received a university, rather than a military, education.
See Also Famous Geologists: Agassiz; Darwin; Lyell; Sedgwick; Smith. History of Geology From 1780 To 1835. History of Geology From 1835 To 1900. Palaeozoic: Ordovician; Silurian; Devonian; Carboniferous.
Further Reading Geikie A (1875) Life of Sir Roderick I. Murchison. . . Based on his Journals and Letters With Notices of his
Scientific Contemporaries and a Sketch of the Rise and Growth of Palaeozoic Geology. London: John Murray (reprinted in facsimile by Gregg International Publishers Ltd, 1972). Oldroyd DR (1990) The Highlands Controversy: Constructing Geological Knowledge through Fieldwork in Nineteenth-Century Britain. Chicago and London: Chicago University Press. Rudwick MJS (1972) Levels of Disagreement in the Sedgwick–Murchison Controversy. Journal of the Geological Society 132: 373–375. Rudwick MJS (1985) The Great Devonian Controversy: The Shaping of Scientific Knowledge among Gentlemanly Specialists. Chicago and London: Chicago University Press. Secord JE (1986) Controversy in Victorian Geology: The Cambrian–Silurian Dispute. Princeton: Princeton University Press. Stafford RA (1989) Scientist of Empire: Sir Roderick Murchison, Scientific Exploration and Victorian Imperialism. Cambridge, New York, Port Chester, Melbourne and Sydney: Cambridge University Press. Thackray JC (1976) The Murchison–Sedgwick Controversy. Journal of the Geological Society 132: 367–372.
Sedgwick D R Oldroyd, University of New South Wales, Sydney, Australia ß 2005, Elsevier Ltd. All Rights Reserved.
Introduction Adam Sedgwick (Figure 1) was born in 1785 in the village of Dent in the Yorkshire Dales, northern England, son of the local vicar and third of a family of seven. He died as a Fellow of Trinity College and Professor of Geology at Cambridge in 1873. He attended Sedbergh School near Dent, and with help from a notable local amateur mathematician, John Dawson of Garsdale, obtained a scholarship to Trinity, where he studied mathematics. He was named 5th Wrangler (fifth in the list of first-class honours students) in 1808. Following further examination, Sedgwick obtained a College Fellowship in 1810 and taught undergraduate mathematics. He was ordained in 1817. On becoming a permanent member of college, Sedgwick also committed himself to bachelorhood. During his life as a geologist, he proved to be extremely energetic in the field, covering large distances in a day. In Cambridge, he was quite often indisposed, but his chronic health
problems apparently disappeared once he got into fieldwork. Though a gifted mathematician, Sedgwick did not make a career in that discipline. From fragmentary autobiographical notes, he evidently had some geological interests from an early age, and he ‘geologized’ on the Continent in 1816. Also, he was ‘introduced’ to the Geological Society of London in 1818. Even so, it is surprising that his scientific accomplishments were thought sufficient to secure the Cambridge chair in geology that year. He was elected Fellow of the Royal Society in 1821, John Herschel heading the list of those who nominated him. Sedgwick was President of the Geological Society in 1829–31, and President of the British Association when it met in Cambridge in 1833.
Geological Work On obtaining his chair, Sedgwick threw himself into geology. He started his annual fieldwork in southern England, then worked his way northwards to Northumberland, and in the years 1822–24 he made the first systematic survey of the Lake District. He obtained topographic maps of the region, ‘recognized’ certain rock units, and systematically covered
FAMOUS GEOLOGISTS/Sedgwick 217
Figure 1 Portrait of Adam Sedgwick (1785–1873); the original is in the Sedgwick Museum, Cambridge. Copyright: The Sedgwick Museum of Earth Sciences.
the region over three seasons, colouring in his maps according to his selected lithological units. Sedgwick did not look much for fossils, but measured strata and cleavage dips and the alignments of beds, folds, faults, joints, and cleavage planes. Faults sometimes could be seen on the ground. At other times, they became apparent when the different rock types were coloured onto the maps. Sedgwick’s labour and energy were immense. Armed with hammer, acid bottle, map, compass, clinometer, and notebooks, Sedgwick tried to determine the structure of that complicated region. Trained in mathematics, the neophyte geologist was trying to ascertain whether the strata displayed any regular geometric pattern. They hardly did, but when Sedgwick published his work he sought to subsume it under the theory of Le´ once E´ lie de Beaumont, according to which, as the Earth cooled and contracted, it supposedly formed a regular fold pattern in its crust, with mountain ranges of similar age having similar alignments. The theory never exerted much influence in Britain, and Sedgwick soon gave up the idea; but the fact that he sought to deploy the French theory suggests that he was interested in a geometrical (mathematical) theory of the earth. This was consistent with the Cambridge tradition, which found expression in the activities of the Cambridge Philosophical Society, which Sedgwick helped found in 1819. He wanted a quantitative geology, with mathematically formulated laws. However, his later Lakeland work (assisted by amateur collectors) used fossils, and by the end of his career, he had worked out a stratigraphic order for the sedimentary rocks compatible with that later developed on biostratigraphic principles. Sedgwick also recognized the
rocks of central Lakeland for what they were: the relics of ancient volcanoes. He referred to waterdeposited volcanic ash deposits as volcanic mud. From his Lakeland work, Sedgwick came to understand (and publish) the distinction between bedding and cleavage, but the distinction was acquired from the local amateur Jonathan Otley, who probably got it from quarrymen. Sedgwick’s Lakeland mapping revealed the existence of large tear-faults in some of the strata, and the eastern boundary of the region was marked by a huge normal fault. Hence, he suggested that the area had been affected by great earth movements. Using terminology proposed in the 1830s by his Trinity colleague, William Whewell, Sedgwick was a ‘catastrophist’. Sedgwick soon met Roderick Murchison (see Famous Geologists: Murchison), who wanted someone to show him how to make sense of ancient rocks in mountainous regions, and together they undertook a lengthy reconnaissance journey round the north coast of Scotland in 1827, unfortunately correlating the eastern and western sandstones of northern Scotland (now regarded as Devonian and Precambrian, respectively). In 1829, they made an extensive tour of the Continent, meeting European professors and travelling to Germany, Bohemia, Hungary, Austria, Switzerland, and Italy. This greatly extended Sedgwick’s experience, especially in the ‘‘focus of Wernerian geology,’’ southern Germany, which he found to be ‘‘the most decidedly volcanic secondary country I ever saw’’. He observed granite veins and inclined or even overturned Secondary rocks (a term used in the nineteenth century as a synonym for the German term Floetz; later for the strata ranging from Silurian to Cretaceous; and later restricted to the Mesozoic Era). This demolished his earlier adherence to Neptunism and he publicly repudiated the doctrine in 1831. Observations in Italy clearly suggested uplift, which was not part of the Wernerian repertoire. On the other hand, Sedgwick was inclined to ascribe the movement of (glacial) erratic boulders to the action of catastrophic floods, but some Swiss deposits could have been emplaced by the bursting of lake barriers. He rejected the idea that ‘diluvium’ was all deposited in the Noachian Flood, but was critical of Charles Lyell’s belief that conditions on Earth were essentially similar through time (see Famous Geologists: Lyell). In the 1830s, Sedgwick collaborated with Murchison in Wales, trying to bring order to the strata there. The strata in the mountains of Snowdonia seemed to have analogy with those of the lakes. Sedgwick tackled them, working on somewhat similar lines, and making a traverse north-west to southeast across Snowdonia in 1832. He unravelled the
218 FAMOUS GEOLOGISTS/Sedgwick
structure to some extent, and although the rocks seemed to have few fossils, the Cambrian System was introduced, largely on the basis of Sedgwick’s work. Murchison, starting in the Welsh border region in gentler country with fossiliferous rocks, had an easier time and revealed what appeared to be a new system with its characteristic fossils, dubbed the Silurian. However, the line of boundary between the two systems was not established at the outset of the investigations in 1834, with the result that a bitter feud subsequently broke out between Sedgwick and Murchison, with the former trying to extend ‘his’ system upwards, the latter endeavouring to expand ‘his’ downwards, eventually to the very lowest fossiliferous rocks. (The issues were very complex; it was not until after the protagonists’ deaths that the issues were resolved, by Charles Lapworth, who, in 1879, proposed the Ordovician System to occupy the disputed territory between the Cambrian and Silurian. (see Palaeozoic: Ordovician) Sedgwick had complained, with reason, that materials he had sent to the Geological Society were changed so as to accord with Murchison’s views, without Sedgwick’s knowledge or consent. The situation grew so bad between the two that after 1853, the Geological Society declined to accept further papers by the protagonists of Siluria or Cambria. Sedgwick felt grievously ill treated and snubbed by the Society. The battle became transferred to the forum of the British Association, but after 1854, Sedgwick withdrew from that body also, so far as the Cambrian and Silurian were concerned, and continued the battle from Cambridge and in the pages of the Philosophical Magazine. Some of the stratigraphic formations and their classifications are shown in Figure 2. It should be noted that the rocks that Murchison allowed to be Cambrian in 1859 were the unfossiliferous Longmynd rocks, later classified as Precambrian. (Murchison also allowed Sedgwick the unfossiliferous Torridonian Sandstone in Scotland, also now regarded as Precambrian.) Initially, Murchison won the battle, partly because he had better fossil evidence, and placed full reliance on it. Also, he had strong influence in the Geological Society and became Director of the Geological Survey in 1855, and his classifications were used by the survey officers. Sedgwick had fewer allies, mostly at Cambridge. For the rocks he was dealing with, he had to rely on structural understanding and lithologically based mapping to a greater extent than did Murchison. (Graptolites were not regularly used for stratigraphic correlation in the mid-nineteenth century.) However, Sedgwick succeeded in showing, on palaeontological grounds, that the claimed unity of Murchison’s Silurian System was flawed. In 1852,
Sedgwick and his assistant Frederick McCoy found that one of Murchison’s Silurian formations, the Caradoc, had rocks containing two distinct faunas, as shown by the palaeontological determinations of McCoy and John Salter. There had been erroneous correlations; the same term, ‘Caradoc Sandstone’, had been applied to different series of rocks; and there should be an unconformity within the Caradoc, as Murchison then understood it. Sedgwick proposed the division of Murchison’s Caradoc into the Caradoc Sandstone, containing fossils such as Trinucleus, and an upper May Hill Sandstone, containing Pentamerus species. This eventually turned the tide against his Silurian being regarded as a coherent system. The Survey sought to retrieve the situation by adopting the terminology ‘May Hill Sandstone Llandovery’ rocks, regarding them as a kind of passage or ‘Intermediate Series’ between the Upper and Lower Silurian. There were repercussions, too, for the interpretation of Murchison’s Llandeilo. This battle was fought with extreme vehemence. Both geologists attached their names and reputations to ‘their’ system. The battle seemed to exemplify the height of the colonial era, with Sedgwick and Murchison trying to extend their empires. Murchison was popularly called the ‘King of Siluria’. Both men tried to rewrite history in their historical accounts of the events. In Sedgwick’s case, this may have been partly due to failing memory. Earlier, there had been a bitter controversy in Devonshire, where, while still friends, Sedgwick and Murchison began to unravel the structure and stratigraphy of the area, in the process becoming involved in controversy with Henry De La Beche, the first Director of the Geological Survey. From this acrimonious debate emerged the concept of the Devonian System. The so-called Old Red Sandstone was the unit well known in eastern Scotland as lying unconformably over Silurian strata. It was mapped by William Smith as ‘Red and Dunstone’. He placed it below the Coal Measures and below a limestone that cropped out in Derbyshire and elsewhere. In Devonshire, there occurred rocks with plant remains that appeared to De la Beche to belong to the old Transition/Greywacke series (Cambrian or Silurian rocks). In Murchison’s opinion, however, the plant-bearing rocks could not be so old: they must be from the Coal Measures. But he had not then been to Devon to see the rocks for himself. Murchison then combined forces with Sedgwick to combat De la Beche’s interpretation. It was an issue of more than academic significance because it bore on the question of the possible extent of coal-bearing rocks. The plant-bearing rocks overlay contorted rocks of ancient appearance, but these contained corals
FAMOUS GEOLOGISTS/Sedgwick 219
Figure 2 Classification of British Lower Palaeozoic Rocks. Reproduced from Secord JA (1986) Controversy in Victorian Geology: The Cambrian– Siurian Dispute, p. 287. Copyright ß1986 by P.U. Press. Reprinted by permission of Princeton University Press.
different from those in the Silurian. In the opinion of the coral expert William Lonsdale, the corals were intermediate between Silurian and Coal Measure types. Thus, the Devon rocks might be situated between the Silurian and the Carboniferous. So, in 1839, Sedgwick and Murchison proposed the Devonian System, being one that had different facies in different localities. Here the palaeontological evidence of corals was taken to outweigh the uncertain stratigraphic reliability of plant fossils and the structural arguments advanced by De la Beche. The issues were debated with considerable rancour and again illustrate the character of stratigraphic controversies in the nineteenth century. But this time, Sedgwick and Murchison were on the same side and the debate
never got quite so out of hand as did the Silurian/ Cambrian contest.
Sedgwick as a Teacher; Other Activities, Beliefs, and Character At Cambridge, Sedgwick gave an annual course of lectures and built up the university’s geological collections, partly from his own collected specimens, but also by donations and purchases. His summer fieldwork was done at his own expense. Partly for this reason, he took a ‘second job’ in 1834, as a canon at Norwich Cathedral. This might have been a sinecure, but Sedgwick took his responsibilities seriously, and resided in Norwich for several months each year, also
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220 FAMOUS GEOLOGISTS/Sedgwick
encouraging the development of a museum in the city and giving geological lectures. Sedgwick was a strong supporter of amateur science and assisted the natural history society in Kendal, near Dent. Sedgwick was a renowned orator – or preacher and lecturer. Science lectures were not a required part of the Cambridge curriculum when he gave his first course in 1819, but he attracted many students and dons to his lectures. His course was repeated until 1859, when he was 74. He spoke extempore about geological principles and his recent fieldwork, rather than about unnecessary minutiae. His lectures, utilizing specimens and maps and diagrams to explain his ideas, were popular, and he also led groups on horseback on field excursions round Cambridge. On a famous occasion at the British Association meeting at Newcastle in 1838, he spoke in the morning at Tynemouth beach to a group attending the meeting; and by the afternoon he had attracted a crowd of thousands, expounding the relationships (as he saw them) between geology, political economy, natural theology, and patriotism, reportedly drawing tears of emotion from some auditors. As John Herschel described it, Sedgwick led them on from the scene around them to the wonders of the coal-country below them, thence to the economy of a coal-field, then to their relations to the coal-owners and capitalists, then to the great principles of morality and happiness, and last to their relation to God and their own future prospects. (Clarke and Hughes (1890).)
In this can be seen the relationship between Sedgwick’s science, social, religious, and political philosophy. Implausibly, he supposed that Britain had been specially favoured by God for its place in the world, with its deposits of coal, limestone, and iron ore. Sedgwick was, then, devoutly religious, and a preacher as well as a teacher. From a relatively obscure Anglican background, he rose to be a Cambridge Professor and Vice-Master of Trinity, and one of the leaders of the heroic age of geology. He even met with Prince Albert (whose election to the Chancellorship of the University he promoted) to discuss reforms at Cambridge, and many of Sedgwick’s suggestions were implemented. Though generally amiable, greatly liked and admired, and able to communicate with the full range of society, from quarrymen, to famous writers such as William Wordsworth or Walter Scott, to Royalty, he was uncompromising and dogmatic. He favoured Catholic emancipation, but having become an establishment figure, he did not wish to see the regular order of things upset by scientific theories that seemed to him subversive, or at odds with orthodox Anglican theology. For such
reasons, he was bitterly and publicly opposed to the transmutationist ideas expressed in 1844 by Robert Chambers in his Vestiges of the Natural History of Creation, and was privately grieved by Charles Darwin’s ideas in The Origin of Species (see Famous Geologists: Darwin). He also rejected the land–ice theory of Louis Agassiz (see Famous Geologists: Agassiz).
See Also Famous Geologists: Agassiz; Darwin; Lyell; Murchison; Smith. History of Geology From 1780 To 1835. History of Geology From 1835 To 1900. Palaeozoic: Cambrian; Ordovician; Silurian.
Further Reading Clark JW and Hughes TMcK (1890) The Life and Letters of the Reverend Adam Sedgwick, LL.D., D.C.L., F.R.S., Fellow of Trinity College, Cambridge, Prebendary of Norwich, Woodwardian Professor of Geology, 1818–1873. Cambridge: Cambridge University Press. Oldroyd DR (2002) Adam Sedgwick: a confident mind in turmoil. In: Harman P and Mitton S (eds.) Cambridge Scientific Minds, pp. 64–78. Cambridge: Cambridge University Press. Oldroyd DR (2002) Earth, Water, Ice and Fire: Two Hundred Years of Geological Research in the English Lake District. London: The Geological Society. Rudwick MJS (1972) Levels of disagreement in the Sedgwick–Murchison controversy. Journal of the Geological Society 132: 373–375. Rudwick MJS (1985) The Great Devonian Controversy: The Shaping of Scientific Knowledge among Gentlemanly Specialists. Chicago and London: Chicago University Press. Rudwick MJS (1988) A year in the life of Adam Sedgwick and company, geologists. Archives of Natural History 15: 243–268. Secord JA (1986) Controversy in Victorian Geology: The Cambrian–Silurian Dispute. Princeton and Guildford: Princeton University Press. Sedgwick A and Murchison RI (1835/36) On the Silurian and Cambrian Systems, exhibiting the order in which the older sedimentary strata succeed each other in England and Wales. Report of the Fifth Meeting of the British Association for the Advancement of Science held at Dublin in 1835, pp. 59–61. London: John Murray. Smith C (1985) Geology and mathematicians: the rise of physical geology. In: Harman PM (ed.) Wranglers and Physicists: Studies on Cambridge Physics in the Nineteenth Century, pp. 49–83. Manchester: Manchester University Press. Speakman C (1969) Adam Sedgwick Geologist and Dalesman, 1785–1873: A Biography in Twelve Themes. Broad Oak, London, and Cambridge: The Broad Oak Press Ltd.