Since 1900, the science of geology has grown in a spectacular fashion. Not only have field studies been undertaken throughout vast areas of the earth's surface previously unexplored or only superficially surveyed, but recent discoveries in physics, chemistry, and biology have provided geologists with new techniques of observation and experimentation, and radically new concepts and theories have been developed. This book presents source literature for the most important contributions to this remarkable expansion of geological knowledge. One of the world's most distinguished geologists provides excerpts from sixty-five articles by sixty-three authors, selected with the advice of more than a score of leading scientists from all parts of the globe. Among the subjects discussed in this comprehensive volume are the constitution of the earth's interior, the causes of earthquakes, radioactive timekeepers, the interpretation of submarine features and deep-sea cores, the origin and entrapment of petroleum, and crystal structure. Included are articles which led directly to the development of theories of paleomagnetism, metamorphism, cryopedology, and isostasy. A Source Book in Geology, 1900-1950, makes available several papers previously to be found in the libraries of only a few universities, and eight articles translated into English for the first time, of which four are by leading Soviet geologists.