XXVI REPORT UNITED STATES GEOLOGICAL SURVEY. 



THE VALUE OF PALEONTOLOaY IN THE WORK OF THE SURVEY. 



By examining the publications of the survey, it will be seen that much 

 attention has been given to the ancient fauna and flora of our Western 

 Territories. The memoirs by Leidy, Cope, Lesquereux, Scudder, Meek, 

 ■and White will always remain as imperishable monuments of their la- 

 bors in their respective departments. The value of their studies in con- 

 nection with geologica 1 explorations and surveys is often in danger of 

 being underestimated by not being correctly understood ; but the im- 

 portance of such work may be indicated by the fact that it is upon the 

 study of fossil remains that the whole system of geology was originally 

 based, and which study now forms the only reliable foundation for the 

 •correct classification of the stratified rocks of tl;ie earth. 



The study of the fossil remains of animals and plants not only adds 

 immensely to the sciences of zoology and botany, giviilg them a com- 

 pleteness which could never be attained by the study of living forms 

 alone, but it has immediate and direct x)ractical application in the eluci- 

 dation of the systematic geology of every region as well as a general 

 and universal classification of the stratified rocks. It is unfortunately 

 the case that many attempts have been made by persons reporting upon 

 the geology of certain districts to base the classification of the formations 

 within it upon the lithological characteristics alone, ignoring the fossil 

 remains as not being of practical value for such purposes. While this 

 method of classification is often api3roximately correct for limited areas, 

 it is even in such cases often erroneous and always subject to serious 

 error, and in larger regions wholly unreliable. The history* of geology 

 contains cases in which resurveys of considerable districts, at great ex- 

 pense, have been rendered necessary by a failure to follow the indications 

 afforded by the fossil remains of the strata concerned. 



The folio wing brief statement maybe taken as illustrating the method 

 of applying a knowledge of fossil remains to the classification of the 

 strata containing them. The different groups of strata, or the forma- 

 tions that make up the great series of stratified rocks of the earth, from 

 the earliest to the latest formed, are each, respectively, characterized by 

 their own peculiar kinds or types of fossils. The paleontologist studies 

 these, and, by familiar acquaintance with their respective characteristics, 

 he is able to recognize the particular formations to which they belong 

 wherever he may discover them, whether then associated with other 

 formations or not. Bach formation being thus characterized, he finds 

 that they hold definite and invariable relations of superposition to each 

 other ; and that this order of their relation is never interchanged or re- 

 versed ; for an animal or vegetable type once introduced and become 

 extinct has never been repeated, but it has left the evidence of its former 

 existence to mark an epoch in the passage of geological time. By this 

 means the paleontologist is able to determine the position in the great 

 scale of formations, any one of these that he may discover in any i)art 



