This is a popular book and is based on the Silliman Lecture of 1952 delivered at Yale University.

It briefly outlines some of the work done on material collected from the deep-sea floor, particularly by the Swedish Deep-sea Expedition of which the author was leader. It is of necessity both a concentrated outline of fact, with considerable speculation, and also somewhat out-of-date since so much work has since been done on the subject. It covers a wide field and contains a number of useful references, and is vividly written.