George Thom, son of William Thom and his wife Barbara Sheriff, studied for some time at the University of Aberdeen before he was accepted as a missionary candidate by the London Missionary Society in 1809 and enrolled at the seminary in Gosport, in the south of England, for two years. On being ordained in 1812 he was sent out to Calcutta (now Kolkata, India) to do missionary work, but upon arriving at the Cape of Good Hope on 24 October that year was instructed to remain there. He attended mainly to the religious needs of soldiers, sailors, Hottentots and slaves, In 1813 he formed the Church of Jesus Christ amongst Scottish soldiers based at the Cape and drew up a constitution for it entitled Doctrine, practice and order. His church is regarded as the first Presbyterian Church in South Africa and its constitution is an important source on the local development of ecclasiastical law. On 31 October 1814 Thom married Christina L. Meyer, but she died in March 1816 giving birth to her first son. On 11 August the next year he married Neeltje M. Vos. He became the de facto superintendent of the London Missionary Society's affairs at the Cape. Among others he spoke out against the morals and behaviour of the society's local missionaries. However, he also took a leading role in informing the directors of the society about the grievances of its missionaries, particularly with regard to salaries and working conditions. In August 1817, he arranged a meeting of missionaries in Cape Town and when its demands were not met by the directors he and several others resigned from the society in September 1818. In November 1818 Thom, who spoke Dutch fluently, was appointed as a minister of the Dutch Reformed Church at Caledon, working among the Hottentots and lepers. He also sold bibles for the British and Foreign Bible Society. During a visit to Britain from 1820 to 1822 he recruited some Scottish ministers and teachers at the request of Governor Charles Somerset. The teachers included James R. Innes* and Archibald Brown*. At this time the University of Aberdeen conferred an honorary Doctor of Divinity (DD) degree upon him. In Augst 1825 he was appointed minister of the Dutch Reformed congregation at Tulbagh. He was a dedicated man who served the church in various leadership positions and made important contributions to the regulations dealing with church administration and discipline. His writings included Narrative of the last sickness and death of Mr Richard Shepherd, merchant, at the Cape of Good Hope (London, 1816). In 1822 he donated eleven volumes dealing with Scottish ecclesiastical law to the South African Library in Cape Town (founded in 1818). Thom was an honorary member of the Literary Society of Bombay and a corresponding member of the South African Institution - the firs purely scientific society at the Cape, founded in 1829. His scientific interests centred around fossils. His only publication on the subject, Remarks on the geology of South Afirca, was published in the South African Quarterly Journal (No. 3, pp. 269-271) in 1830 and was the first significant geological paper to be published locally. It was based on a lecture he delivered before the South African Institution in Cape Town in May 1830. He wrote that he was given his first fossil in 1814, a kind of cockel or muscle, with a slit in both valves (probably a bivalve of the genus Nuculites) found in the Cold Bokkeveld. Subsequently he collected more than 20 specimens himself near the Cedarberg range, also many shells, trilobites and the stems of sea lillies (Class Crinoidea) in other locations. After reading the available literature and consulting local residents he concluded that Mr Enislie*, a merchant of Cape Town, was the first person to recognise and collect such fossil remains, at Keizie Baths, behing Cogman's Kloof, in 1804 or 1805. Thom received specimens and notes on the strata from the discoverer and confirmed the finds by visits to the site in 1817, 1818 and 1828. He was also aware of fossil shells of a different kind found in limestone in the southern Cape coastal regions between Caledon and Albany, including those at Uitenhage, but considered these to be younger than the Bokkeveld fossils. Shells found near the sea on the west coast of the colony he also considered to be of more recent origin. He sent some geological specimens to professor Couper of the Huntarian Museum in Glasgow. Thom was the second person to describe the Cango Caves (the first was Petronella S. Faure, who provided a brief account in 1808). He visited the caves on 14 October 1816 and drew a cross-section, Plan of the grotto in the Kango (now in the Cape Town Archives Repository) on which Van Zyl's Hall, The Registry, and Botha's Hall were first named. Several additional parts of the cave were discovered by him and his party, and named after themselves. His interest in caves is further shown by an advertisement in the Cape Town Gazette of 10 January 1818, announcing that a work by him, The caves of South Africa: A description of the grotto in the Cango and of several remarkable excavations along the coast, was to be published in London later that year. Profits from its sale were to go to mission work. Although several prominent persons, including Lord Somerset and W.J. Burchell*, subscribed to the work, it does not appear to have been published. After his return from Scotland in 1822 Thom started sending plants to W.J. Hooker, professor of botany at Glasgow University, at first from Caledon and later from Tulbagh. He also bought plants for Hooker from other collectors. In June 1832, in consequence of an indisposition he offered his collection of rocks and minerals for sale in the South African Commercial Advertiser. The collection consisted of over 1200 specimens of local rocks, minerals, metallic ores and fossils, with precise localities noted, as well as a comparative collection of rocks, minerals, ores and fossils from Great Britain, Ireland, the African islands and other localities. What happened to the collection is not known. The next year Thom resigned from the ministry as a result of increasing nervous tension and afterwards was confined in a hospital. At the time of his death he was survived by his second wife and nine children.