Alexander H. Green, British geologist and mathematician, studied mathematics at the University of Cambridge during 1851 to 1855 and was elected a Fellow of Gonville and Caius College in the latter year. Staying on at the college he taught mathematics and attended lectures in geology, and was awarded the degree Master of Arts (MA) in 1858. He left in 1861 to take up a post with the Geological Survey of England and Wales. During the next thirteen years he mapped the geology of extensive areas of the Midlands and north of England and became a leading authority on the coal-bearing strata and coal-mining geology of Yorkshire. He was elected a Fellow of the Geological Society of London in 1862 and a Fellow of the Royal Society of London in 1886. In 1874 he was appointed professor of geology and mining in the Yorkshire College, Leeds, where from 1885 he also performed the duties of the professor of mathematics. During his time at Leeds he wrote a book on physical geology (1876) which became a leading textbook and was published in various editions over the next 22 years, and published Geology for students and general readers (1876). His Geological Survey memoir, Geology of the Yorkshire coalfields (1878) remained a classic for many years. In addition he wrote about 40 papers, mainly on the geology of England and particularly the Yorkshire coal fields. In 1866 he married Mary Marsden, with whom he had two sons and a daughter.
In 1882 Green came to the Cape Colony at the request of its government to examine and report on the coal deposits of the colony. Among others Dr W.G. Atherstone* took him to outcrops of the Dwyka conglomerate near Grahamstown. Before his return to England, on 5 March 1883, he addressed a meeting of the South African Philosophical Society on the geological observations he had made, with special reference to the scientific problems which he thought local geologists should investigate. Notes on his address were published in the society's Transactions (Vol. 3, pp. 27-29). A more comprehensive account of the results of his investigation, Report on the coals of the Cape Colony, was published as a Cape Parliamentary Report in London in 1883. It contained, among others, descriptions of the mines and outcrops visited in the Indwe and Stormberg districts, other supposed occurrences of coal, prospecting for coal, the development of the colony's coal trade, remarks on the formation of coal, and an attempt to correlate various geological sections. Five years later he published a comprehensive and influentual paper, "A contribution to the geology and physical geography of the Cape Colony", in the Quarterly Journal of the Geological Society (1888, Vol. 44, pp. 239-269). Although he was an accomplished geologist, his journey through the colony was too hurried for a detailed investigation of its geology. For the pre-Karoo strata he accepted mainly the successions proposed by A.G. Bain* and E.J. Dunn* (the latter was government geologist at the time of Green's visit). The Karoo beds themselves he placed in five groups, mistakenly concluding that in the south the Dwyka conglomerate rested unconformably on the Cape rocks. He differed from Dunn in thinking (wrongly) that the shales in the vicinity of Kimberley were distinct from, and higher up in the succession than, the more southern Dwyka shales; neither did he accept Dunn's conclusion in 1886 that the Dwyka conglomerate could be traced continuously through the north, west and south sides of the Karoo. He did not accept a glacial origin for the Dwyka conglomerate either. And at the Kimberley mine he confused the lavas of the Vaal River valley with a sheet of Karoo dolerite. He was greatly impressed by the extent of igneous activity which resulted in the large scale intrusion of Karoo dolerite and the extrusion of the Stormberg lavas, and described the microscopic characteristics of both the intrusive and extrusive rocks, pointing out the resemblances between them as evidence of their common origin. In his report on colonial coal he introduced the term Molteno beds for the coal measures, but his view of their value was no more informative than the opinions of Dunn and others who had investigated the deposits.
Green became professor of geology at the University of Oxford in 1888. In 1890 he was president of the section for geology of the British Association for the Advancement of Science. His strengths lay in his fieldwork and in aspects of physical geology where he could apply his knowledge of mathematics. He was a clear teacher and wrote well, worked also as a consultant geologist, and was an examiner in geology for various institutions. He suffered a stroke in 1896 and died near Oxford. At the time of his death he was a vice-president of the Geological Society. His ability, wide interests and charming manners endeared him to many colleagues.