Arthur W. Rogers, geologist, was the son of George Rogers, a teacher, and his wife Emma Mills. He was educated at a private school and subsequently (1885-1891) at Clifton College, Bristol, where he developed an interest in natural history and geology. From 1891 to 1895 he studied at Christ's College, Cambridge, graduating in 1894 as Bachelor of Arts (BA) with honours in geology and zoology, and winning the Harkness Scholarship in geology the next year. During his student days he made a tour of several months through Germany. He learned much about field surveying from George W. Lamplugh*, with whom he visited the Isle of Man while a student.
In 1895 Rogers accepted an appointment as assistant geologist to the newly established Geological Commission of the Cape of Good Hope. He brought with him a large collection of rocks from England, which he presented to the South African Museum, Cape Town, in 1899.
The Geological Commission of the Cape of Good Hope instituted the first proper geological survey of the Cape Colony, with a view to investigating and mapping its geology. The Commission's geologist was Dr G.S. Corstorphine*, with Rogers and E.H.L. Schwarz* as assistant geologists. From 1896 to 1902 Rogers and Schwarz did extensive field work, either separately or together, mostly during the winter. Their main findings on the structure and stratigraphy of the south-western Cape have stood the test of time and formed the basis for later more detailed work. Rogers was a meticulous observer and, in contrast to Schwarz, cautious in his conlusions. Among others he helped to clarify the structure of the Cape Folded Belt by discovering that the Swartberg is built up mainly of the Table Mountain Sandstone, which has been folded to form a second mountain chain, parallel and similar to the southern Langeberge. In 1899 he began a preliminary investigation of the pre-Cambrian complexes near the Orange River. These proved too difficult to interpret at the time, but during subsequent years he was able to reach more clarity regarding their structure. In 1900 he worked mainly in the mountainous regions of the Clanwilliam and Van Rhynsdorp districts. An important discovery here was a glacial zone in the Table Mountain sandstone, containing finely striated inclusions. His observations were described in two papers published in the Transactions of the South African Philosophical Society in 1902 and 1905. During the Anglo-Boer War (1899-1902) his work was confined to the south coast of the colony and to the Transkei and Pondoland in the east. His large collection of fossils from the Upper Cretaceous deposits at the mouth of the Umzamba River was described by H. Woods* in 1906. After only eight years of field observation Rogers was able to write An introduction to the geology of Cape Colony (1905, 463p), a most instructive book based on a wealth of new information that was skilfully synthesized. A second edition, by Rogers and A.L. du Toit*, appeared in 1909.
Rogers spent most of the year 1902 on long leave in England. The next year he succeeded Corstorphine as director of the Geological Commission, but continued with survey work. Later that year he temporarily lectured on geology at the South African College, in place of Professor Andrew Young*. During 1904 he discovered that the folded slates and limestones near Vanrhynsdorp, hitherto regarded as of the same age as the Malmesbury Group, was in fact younger, as it overlay conformably the Nieuwerust quartzites. In 1905 he made the important discovery that a stone artefact, later identified as of Mossel Bay type, was associated with the six meter raised beach at Klein Brak. That same year he made a systematic survey of the Cretaceous beds in the vicinity of Uitenhage. The fossil molluscs he collected were described by F.L. Kitchin* in 1908. For the next ten years Rogers worked in the dry northern part of the Cape Colony and gradually elucidated its geological complexities. The University of Cambridge awarded him the degree Doctor of Science (ScD) in 1908. During these years his affiliation was often given as the South African Museum, as he was honorary keeper of its Geological Department from 1902 to 1916.
Following the formation of the Union of South Africa in 1910 the Geological Commission was amalgamated with the Geological Survey of the Transvaal to form the Geological Survey of the Union of South Africa. Rogers became its assistant director in 1912, though his headquarters remained in Cape Town. Most of his work up to this time was published in the 16 annual reports of the Geological Commission and in a number of geological maps, but he also contributed papers to the Transactions of the South African Philosophical Society, the Geological Society of South Africa, the Royal Society of South Africa, and other journals. In 1914 he was invited to tour German South West Africa (now Namibia) in the company of the German geographer Professor Fritz Jaeger and Hans von Staff. This visit proved highly instructive for his study of the geology of Namaqualand, as he was able to compare the rocks found north and south of the Orange River. It also enabled him to describe the geology of the large volcanic vent now known as Brukkaros Mountain. Soon afterwards World War I (1914-1918) broke out and the Union of South Africa found itself at war with Germany and its African colonies.
In 1916 Rogers succeeded H. Kynaston* as director of the Geological Survey and moved to the Transvaal. There he became mainly concerned, in addition to his administrative duties, with the detailed mapping of the outlying portions of the Witwatersrand Supergroup, and for this purpose made his headquarters first at Johannesburg and then at Heidelberg. He described the goldfields of that district in 1921-1922 and then moved on to the Klerksdorp goldfields. During 1924-1925 he visited England again on leave, during which he presented three lectures on the geology of South Africa at the University of London.
Rogers served as president of the Chamber of Mines during 1928-1929. In the latter year he presided over the Fifteenth International Geological Congress, held in Pretoria. That same year he served as joint vice-president of Sections C (Geology) and E (Geography) of the British Association for the Advancement of Science when it held its annual meeting in South Africa. The next year he joined the Vernay-Lang expedition to the Kalahari. His study of its geology formed the subject of two consecutive presidential addresses before the Royal Society of South Africa in 1934 and 1935, dealing respectively with the underlying geology and surface geology of the region. It was his last important field investigation. In addition to his own work, he supervised the publication of many maps and memoirs of great scientific and economic importance compiled by the staff of the Geological Survey.
In 1932 Rogers retired from his directorship. Following another visit to England he settled in Mowbray, Cape Town. A major achievement during the next few years was his monograph on The pioneers in South African geology and their work, published as an annexure to Vol. 39 of the Transactions of the Geological Society of South Africa (1937). This masterly account is perhaps his crowning achievement. Much of his time during his retirement was taken up also by laboratory work, particularly a study of diatoms (microscopic unicellular algae with siliceous cell-walls), their present and past distribution in southern Africa and the evidence they might provide for climatic changes during the Tertiary and Quarternary. Despite suffering a severe heart attack in 1938 he was able to complete an account of "The diatom floras", which was published shortly after his death as part of Memoir No. 42 (1947) of the Geological Survey.
Rogers's geological work was characterised by an attention to detail and an appreciation of the microstructure of matter, while his writings contain very few theoretical or speculative ideas. In more than 120 publications he dealt with a variety of topics, among them his discovery of glacial beds in the Witwatersrand Supergroup, Numees Formation, Griquatown Group, and Table Mountain Group; his discovery and naming of the Griquatown, Matsap, Waterberg, Koras, Wilgenhoutdrift and Suurberg volcanic groups; the post-Cretaceous climates of South Africa; the origin of the great escarpment; the magmatic copper deposits of Namaqualand; the Blinkklip breccia; the crocidolite deposits of Griqualand West; the prospect of finding oil in the southern Karoo; the first description of local radioactive minerals; the "roaring sands" of Griqualand West; the Tygerberg anticline; the Uitenhage fauna; the pans of the Kalahari; and Verneukpan. In 1925 he wrote "The geological structure of the Union" (34p), an explanation to accompany the Geological Survey's first geological map of the Union of South Africa.
Rogers was one of the greatest geologists South Africa has seen. The high standard of his work and the high regard in which he was held are shown by the honours conferred upon him by both local and British institutions. He was elected a Fellow of the Geological Society of London in 1906, receiving its Bigsby Medal in 1907 and its Wollaston Medal in 1931; was elected a Fellow of the Royal Society of London in 1918; and in 1935 received an Honorary Fellowship of Christ's College, Cambridge. In South Africa honorary doctorates were conferred upon him by the universities of Cape Town (1923) and the Witwatersrand (1938). He became a member of the South African Philosophical Society in 1896, was elected a foundation Fellow of its successor, the Royal Society of South Africa, in 1908, and served as president of the latter from 1933 to 1935. In 1903 he joined the South African Association for the Advancement of Science, received its South Africa Medal (gold) in 1913, and served as president in 1921/2. As a member of the Geological Society of South Africa from 1903 he served as president in 1915 and received its Draper Memorial Medal in 1936. He joined the South African Biological Society in 1917, receiving its Captain Scott Medal in 1928. In 1917 he also became a foundation member and first president of the South African Geographical Society and addressed its members on "Namaqualand". Many other local and overseas scientific societies had him as either an ordinary or honorary member.
Rogers was an examiner in geology for the University of the Cape of Good Hope in 1898 and 1899. He was a lover of books and after his death his personal scientific library was presented to the Royal Society of South Africa. As a keen photographer his albums contained numerous instructive geological and geomorphological illustrations, most developed and printed by himself. He had a happy disposition and was a genial conversationalist. A true researcher, he had no patience with bureaucratic procrastination, political opportunism, or the financial aspects of mining. On 12 April 1902 he married Hester J. van der Riet (sister of Professor B. de StJ. van der Riet* of Stellenbosch), but they had no children.