A thesis submitted to the Department of Geology of the University of the Witwatersrand in partial fulfillment of requirements for the degree of Doctor of Philosophy. / This report describes the results of a comprehensive investigation into the classification, distribution, composition, origin, age, and engineering properties of calcretes in South West Africa and the Republic of South Africa. Methods of prospecting for calcretes and tests and specifications for their use in road construction in these countries are also considered. All previously published information on Southern African calcretes and much of the world literature is reviewed, the results of the author's own research reported, conclusions drawn on the basis of both, and aspects worthy of further investigation indicated. 1,070 pages, 75 plates, 106 figures, 172 tables, 13 maps. / Andrew Chakane 2018