PREFACE 



This book had its origin in the attempt to write an introductory 

 work, dealing principally with American Geology, upon the lines 

 of Sir Archibald Geikie's excellent little " Class-Book." In spite 

 of vigorous efforts at compression, it has expanded to its present 

 size, though the difference from the " Class-Book," in this respect, 

 lies not so much in the quantity of matter as in the larger size of 

 the type and illustrations. 



The book is intended to serve as an introduction to the science 

 of Geology, both for students who desire to pursue the subject 

 exhaustively, and also for the much larger class of those who wish 

 merely to obtain an outline of the methods and principal results 

 of the science. To the future specialist it will be of advantage to 

 go over the whole ground in an elementary course, so that he 

 may appreciate the relative significance of the various parts, and 

 their bearing upon one another. This accomplished, he may 

 pursue his chosen branch much more intelligently than if he were 

 to confine his attention exclusively to that branch from the begin- 

 ning of his studies. 



Students, and only too 'often their instructors, are apt to prefer 

 a text-book upon which they can lean with implicit confidence, 

 and which never leaves them in doubt upon any subject, but is 

 always ready to pronounce a definite and final opinion. They 

 dislike being called upon to weigh evidence and balance proba- 

 bilities, and to suspend judgment when the testimony is insufficient 

 to justify a decision. This is a habit of mind which should be 

 discouraged; for it deludes the learner into the belief that he 

 knows the subject when he has only acquired some one's opinions 



