A fascinating book that is not only a survey of geology written in travelogue form, but which is a personal adventure abounding in the penetrating observation of a brilliant scientist and sensitive human being. It is no pat simplification of a complex science: the author flatters the reader by the clear exposition of terms and principles, and the reader travels with him, gaining understanding as the scientist explores problem after problem. Beginning in Africa in 1910, the neophyte geologist is fresh from the university; when he returns to Africa in 1936, having covered much terrain in many parts of the world, his readers too will be wiser. For not only is Hans Cloos a scientist with a real feeling for the meaning and beauty of his world, but he has a gift for conveying his enthusiasm in poetic expression. And the translator, E. B. Garside, has done a beautiful job. The book falls into six parts, for the six explorations. It starts with the geological explanation of the gold of Johannesburg, the diamonds of Pretoria, the discovery in the Erongo Mountains which throws light on the nature of the earth's crust. Next the Dutch East Indies, where his job of prospecting for oil is secondary to his interest in the cultures of the people. In Scandinavia the confounding problem of a range of mountains that seem to move at a pace fast in geologic time absorbs him. America seems somehow less interesting, though his travels in Sierra Nevada brings closer home the changes in the earth. Then in Germany he explores territory already familiar. Finally, in his return to Africa, he concludes with a recapitulation of the scientist's and the reader's first experience. A book for thoughtful reading, which should capture the imagination of anyone with any scientific interest whatever, and fascinate those with more specialized knowledge.