Bonney, Thomas George

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Bonney, Thomas George

(b. Rugeley, England, 27 July 1833; d. Cambridge. England. 10 December 1923)


One of the last links with the heroic age of geology. Bonney was contemporary with Sedgwick. Murchison, Lyell, and Darwin during his early professional life: his pupils included Sollas, Marr, Watts, Teall, and Strahan.

The eldest of ten children born to Rev. Thomas Bonney, headmaster of the Rugeley grammar school, and his wife, the daughter of Edward Smith, Bonney graduated from St. John’s College, Cambridge, as Twelfth Wrangler in the Mathematical Tripos in 1856 and obtained a second-class in the Classical Tripos: illness frustrated his intention to sit for the Theological Tripos as well. After five years as mathematics master at Westminster School, during which time he was ordained a priest and elected to a fellowship at St. John’s, Bonney was recalled to the college as junior dean in 1861, becoming tutor in 1868 and also college lecturer in geology, a subject in which he was until then a self-taught amateur. At that time there were no university lectureships, but Bonney shouldered the main responsibility for university as well as college teaching in the subject during Sedgwick’s declining years and exerted a powerful influence in molding the Cambridge school of geology.

Surprisingly, Bonney was not elected to succeed Sedgwick, and in 1877 he accepted the Yates-Goldschmidt professorship of geology at University College, London. At first conducting his part-time professorial duties from Cambridge, he became secretary of the British Association for the Advancement of Science in 1881, and this brought with it a sufficient increase of income for him to set up house-keeping in London with his sister. As secretary of the Association. Bonney organized its first meeting outside Britain (in Montreal), and during his London residence he became president of its Geological Section. (In 1910 he became president of the Association.) He also served, successively, as secretary and president of the Geological Society of London, and president of the Mineralogical Society. The Royal Society elected him a fellow in 1878; and he also became honorary canon of Manchester. Whitehall Preacher (at the Chapel Royal), and a Hulsean and Rede’s lecturer at Cambridge. Bonney resigned his chair in 1901, but remained “doing fairly lucrative work” as one of the regular writers for a newspaper, the Standard, until 1905, when he returned to Cambridge.

Lack of formal education in geology may have contributed to that independence of outlook which constantly questioned dogma, and his insistence on proof may be attributed to his mathematical training. Bonney would accept no theory until it was exhaus-tively proved, and he inevitably became a formidable controversialist in nineteenth-century geology: “Fine phrases unsupported by facts prove to be no better than cheques without a balance at the bank.” He was profoundly impressed by the Origin of Species, and in one of his presidential addresses lamented that the science of mineralogy “still needs its Darwin”; nevertheless, many contemporary theories and hypotheses came under his stricture.

Bonney’s interest in glaciology was lifelong; it was the subject of his second paper in the Geological Magazine and of his presidential address to the British Association in 1910. Observations on valley glaciers made during his frequent visits to Switzerland caused him to dispute the efficacy of ice as an erosive agent, and he remained unconvinced of the formation of cirques by plucking action or of more than superficial modification of river valleys by moving ice. While tarns and lakelets might be formed by glacial excavation, he could not accept the latter as the origin of larger lakes. Neither could he believe that the Scandinavian ice sheet ever reached the shores of Britain: he contended, inter alia, that the deep coastal trough bordering Norway must have afforded an easy path to the Arctic Ocean. His final presidential address, on the British “drift1” marshaled his difficulties in accepting the land-ice hypothesis without venturing an alternative explanation.

Bonney was a leading figure in the early days of British petrography, following closely in the wake of Zirkel and Rosenbusch. Important studies on basic and ultrabasic igneous rocks led naturally to his demonstration of the true character of British serpentines, and in one of his numerous papers on these rocks he strongly contested Sterry Hunt’s views of their sedimentary origin. As an authority on the Archaean rocks of England and Wales, Bonney became involved in the heated discussions of the age of the Eastern Gneiss (Moinian) of the northwest Highlands of Scotland, and of the age and relations of the metamorphic rocks of the Alps. Rocks for identification and analysis were sent to him from all over the world, and several of his later papers concern the parent rock (eclogite) of the diamond in South Africa. His petrological interests were not, however, confined to igneous rocks, and one of his presidential addresses (British Association, 1886), “The Application of Microscopic Analysis to Discovering the Physical Geography of Bygone Ages,” is a remarkable pioneering achievement in what is now called sedimentology. Bonney was also chairman of the Coral Reef Committee of the Royal Society, which organized and reported on the Funafuti boring.

Bonney was by training and by temperament an exceedingly versatile man: geologist, mathematician, theologian, and classicist; an alpine traveler and a noted climber; a journalist and writer on architecture and scenery: and a draftsman of great merit. But above all, he was an outstanding teacher, and it was through teaching as much as through his prolific writings that he exercised such influence upon nineteenth-century geology. He was one of the first to introduce the examination of thin slices of rocks under the microscope, to lay emphasis on practical work in the laboratory and in the field, and, by his severely critical attitude, to compel his students to seek the facts and the evidence underlying any theory. As a teacher, he put out all his talents at compound interest.


I. Original Works. Bonney was the author of more than 200 scientific papers; a dozen books on geology, travel, architecture, and theology; several volumes of sermons; and a great many newspaper articles. The majority of his scientific papers are in Quarterly Journal of the Geological Society of London, Geological Magazine, and Mineralogical Magazine. His books include The Story of Our Planet (London, 1893); Charles Lyell and Modern Geology (London, 1895); Ice Work Past and Present (London, 1896); Volcanoes (London, 1899); The Building of the Alps (London, 1912); and Memories of a Long Life (Cambridge, 1921).

II. Secondary Literature. Articles on Bonney are “Eminent Living Geologists: The Rev. Professor T. G. Bonney,” in Geological Magazine, 38 (1901). 385–400, which contains a full catalog of his scientific papers to 1901; and W. W. Watts, an obituary notice in Proceedings of the Royal Society, B99 (1926), xvii-xxvii.

O. M. B. Bulman