Bibliographical essays

Summary

THE PALAEO-ECOLOGY OF THE AFRICAN CONTINENT

Although the ancient Egyptians explored the northern part of Africa and traded with West Africa, knowledge of the interior of the continent was scanty. The Greek school at Alexandria gathered important records and it was there that Eratosthenes, about 2000 BC, made the first scientific measurement of the circumference of the earth. It was also in Alexandria that Ptolemy, around AD 150, developed his famous map of the known world, although it has survived only in Arabic and mediaeval versions of his Geographia. Ptolemy's map served as the base for the Arab explorers of the seventh to fourteenth centuries and was modified during the fifteenth and sixteenth centuries as the whole southern coastline became defined. However, details shown in the interior in these early maps are highly speculative and it was not until the middle of the last century that scientific exploration began to reveal a true picture of the interior. The growth of cartography is conveniently considered in Tooley and Bricker (1969) and the progress of exploration presented in maps by Fage (1963). Even in the final decades of the nineteenth century, large areas of the continent were almost unknown and in his classic Das Antlitz der Erde Suess (1885—1901) drew heavily on travellers' reports for the geology of some portions of the continent and had to omit many regions for lack of data. The first government geological survey was only established in 1895 (at the Cape), but mineral exploration led to rapid growth of geological knowledge and the 1920s saw the appearance of several important regional studies, such as Gregory (1921) on East Africa and the rift valleys, du Toit (1926) on South Africa, and the first systematic geology of the whole continent by Krenkel (1925, 1928).