On several occasions I have been asked wh ether topics of earth science could be explained in more or less conventional prose. Of course this can be done. I ho pe chapter I meets with the most extreme wishes in this respect. I even venture to believe that chapters II, IV, VI and VII can also be digested without special strain. Though chapter V, and parts of chapter III may require a special effort of concentration on the part of the reader, there should be nothing in this book that cannot be under- stood by an intelligent person who is willing to try. Sometimes, however, the use of technical terms cannot weIl be avoided without affecting the meaning and accuracy of the ideas. However, I have attempted to restrict the use of these terms to aminimum. Moreover most scientific expressions and terms will be explained when used for the first time and when occur- ring again one will find a reference to these pi aces in the index. Finally a list of the names of geological formations in their proper sequence is made available for consultation in table I, at the end of the Preface (p. XII). Each chapter constitutes a subject in itself. However, as in the author's "The Pulse of the Earth" the reader will find that the different topics demonstrate the deeper correlation that links together a variety of terrestrial processes, which - at first sight _. appear to be unconnected.