PREFACE. 



Two reasons have led the author to give this Manual its 

 American character: a desire to adapt it to the wants of Ame- 

 rican students, and a belief that, on account of a peculiar sim- 

 plicity and unity, American Geological History affords the best 

 basis for a text-book of the science. North America stands 

 alone in the ocean, a simple isolated specimen of a continent 

 (even South America lying to the eastward of its meridians), 

 and the laws of progress have been undisturbed by the conflicting 

 movements of other lands. The author has, therefore, written 

 out American Geology by itself, as a continuous history. Facts 

 have, however, been added from other continents so far as was 

 required to give completeness to the work and exhibit strongly 

 the comprehensiveness of its principles. 



It has been the author's aim to present, for study, not a series 

 of rocks with their dead fossils, but the successive phases in the 

 history of the earth, — its continents, seas, climates, life, and the 

 various operations in progress. Dynamical Geology, contrary 

 to the views of some geologists, has been placed after the strati- 

 graphical or historical portion. It will, however, be found that 

 through the latter the facts have been followed by statements 

 and explanations of principles; so that the student, on reaching 

 the pages treating of Geological Causes, will have already 

 learned much of what they contain. 



As many readers may not be familiar with Zoology, a review 

 of the classification of animals, with many illustrations, has been 

 given before entering upon the Dynamical History of the ancient 

 life of the world. 



