This volume, which is based on the Russian edition published in 1980, presents the fundamentals of mathematical geology. New developments which have taken place in the last ten years or so have been taken into account as far as possible, and this English edition contains two completely new chapters devoted, respectively, to random diffusion processes and a survey of future geological problems. The book has eight chapters. Chapter I deals with the basic question `What is mathematical geology?' Chapter II considers the concept of probability. Chapter III relates this fundamental tool to geological problems with the help of specific examples. Chapters IV-VI cover the theory of random sequence and concentrates on the form which is the most useful to geologists. Chapter VII is dedicated to continuous Markov processes which occur frequently in geological phenomena. The volume concludes with an overview of ideas which have been generated by mathematical geology and which pave the way for the further development of the subject. Many examples are included throughout the text and the volume has a comprehensive subject index.