Geomorphic ideas and view points have evolved enough since publication of Principles of Geomorphology in 1954 to justify a revision of the book. The revised edition does not represent a complete rewriting of the text much of the original material has been retained numerous sections have been rewritten and considerable new material has been added. In order to avoid increasing the size and cost of the book unduly deletion of old material has been necessary. The chapter on Tools of the Geomorphologist was omitted because there is now available adequate source material in this area Pale geomorphology.