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ing a connected account of the earth's history, and of the means by which 

 that history is recorded and read. Antecedent elementary courses in geology 

 will not be necessary to the use of these volumes, though such courses may 

 be helpful. 



The arrangement of themes adopted is such as to bring to the fore proc- 

 esses with which all students are immediately in contact, and which are 

 available for study at all seats of learning. The comm.oner geologic agents, 

 such as the atmosphere and running water, have been elaborated somewhat 

 more fully than is customary, and the common rather than the exceptional 

 phases of the work of these agents have been emphasized, both because of 

 their greater importance and their universal availability. The text has been 

 so shaped as to suggest field work in connection with these topics especially, 

 since work of this sort is everywhere possible. 



After the preliminary outline, which is intended to give some idea of the 

 scope of the science, and of its salient features, and to show the relations of 

 the special subjects which follow, the order of treatment is such as to pass 

 from the commoner and more readily apprehended portions of the subject to 

 those which are less readily accessible and more obscure. Following the 

 same general conception, the treatment of the topics is somewhat graded, the 

 earlier chapters being developed with greater simplicity and fulness, while the 

 later are somewhat more condensed. 



