Principles of Geology
Principles of Geology
This book attempts to summarize some of the knowledge that geologists have won from the study of the earth. A subject so large must be treated very briefly if it is to be presented between the covers of a single book; we have chosen to concentrate on the analysis of processes that are at work upon and within the earth, rather than to present a catalog of descriptive facts and terms. We have felt, too, that the student is entitled to know something of the kind of evidence on which geologic conclusions are based, even though its presentation takes valuable pages that might be used to put forth more facts.
Some teachers will regret our brief treatment of many of the standard topics usually found in textbooks of physical geology. We can only hope that the loss will be balanced by the new material included covering many phases of the science in which rapid advances have been made in recent years, and more particularly by the emphasis on leading the student through approximately the same sequence of reasoning that was used in the historical development of the subject. We believe that the student may retain more of the basic principles on which geology is based if he knows how a geologic map is made, and if he is introduced to Werner's and Desmarest's divergent views on the origin of basalt, than if he is instructed too minutely on the purely technical terminology of landscape morphology or rock classification. It is our hope, too, that such a presentation carries with it an understanding of the intrinsic uncertainties of indirect evidence, upon which so much of geology depends.
Geology, as we know it, could hardly exist without the foundation of stratigraphy, which gave the dimension of time to the science. Accordingly, we have outlined a little of the development of stratigraphy instead of leaving it entirely for a later course in historical geology.
We are indebted for assistance in the preparation of this book to many persons, only a few of whom can be mentioned here. The contribution of Robert R. Compton goes far beyond that indicated on the title page; in addition to preparing the illustrations, he wrote one chapter of the book and acted as critic on all the others.