A CENTURY OF GEOLOGY. 431 



A CENTURY OF GEOLOGY.* 



By Peof. JOSEPH LE CONTE. 



GEOLOGY is one of the youngest of the sciences. It may 

 almost be said to have been born of the present century. It 

 is true that knowledge concerning the structure of the earth had 

 been accumulating ever since the time of the Greeks and Romans; 

 it is true that these materials became more abundant and were 

 better organized in the eighteenth century; but this knowledge had 

 not yet taken form as a distinct branch of science until about the 

 end of that century. There are two distinctive marks of scien- 

 tific as compared with popular knowledge: First, that its funda- 

 mental idea is clearly conceived; and, second, that its method is 

 distinctly inductive. 



1. FtnsTDAMENTAL Idea. — The fundamental idea underlying 

 geological thought is the history of the earth. Now, until the be- 

 ginning of the present century the earth was not supposed to have 

 any history. It was supposed to have been made at once, out of 

 hand, about six thousand years ago, and to have remained substan- 

 tially unchanged ever since as the necessary theater of human his- 

 tory. Changes were known to have taken place and in less degree 

 to be still taking place, but these were not supposed to follow any 

 law such as is necessary to constitute a history, and thus to con- 

 stitute a science distinct from geography. Buffon, about the mid- 

 dle of the last century, did indeed bring out dimly the idea of an 

 abyss of time, preceding the advent of man, in which the earth 

 was inhabited by animals and plants wholly different from those 

 of the present day, but he was compelled by the priests of the Sor- 

 bonne to retract these supposed irreligious views. So tardily was 

 the fundamental idea of geology clearly conceived that Comte, 

 the great originator of scientific philosophy, in his classification of 

 the sciences in 1820, denied a place to geology because, according 

 to him, it was not a distinct science at all, but only a field for the 

 application of all the sciences. It is evident that he did not per- 

 ceive the fundamental idea underlying geology and distinguishing 

 it from geography — viz., a life history of the earth through all 

 time. The claim of geology to a place in a scheme of classification 

 is exactly the same as that of astronomy. As astronomy is a field 

 for the application of mathematics, mechanics, physics, and, re- 

 cently, chemistry, but is distinguished from them all by its charac- 

 teristic fundamental idea of illimitable space, so geology is a field 

 for the application of all other lower sciences, but is distinguished 



* In this article I have attempted to give only the development^of geological thought. 



