GEOLOGY 127 



sciences nature is observed only in her normal action. Man 

 uses no means of reproducing her processes, but observes 

 them only as they take place in nature in the normal way. 



Physics, chemistry, and certain phases of biology are exper- 

 imental sciences. Astronomy and geology are observational. 

 Geology is so necessarily. The colossal scale on which nature 

 performs her operations and the forces she uses to bring them 

 about make it practically impossible for man to reproduce 

 them on a scale sufficiently large to yield any result that can 

 have much comparative value. It is true that experiment can 

 be utilized in geological investigation to a certain extent, but 

 to a very slight one. Man is wholly at the mercy of nature 

 in this respect. He cannot produce earthquakes, raise moun- 

 tains, construct and operate volcanoes, or erode mountain 

 ranges in order to observe the interaction of forces and the 

 order of events that take place. The dignity and power of 

 mother earth do not permit the geologist to cause her, by 

 means of a sort of teasing process, to perform a special set 

 of operations solely for the amusement or even the instruc- 

 tion of man. He may observe her in her daily work, but 

 undue familiarity is not permitted. 



Geology treats of the histology, anatomy, physiology, and 

 morphology of the earth as it exists at present and of the 

 stages passed through by it since the formation of the first 

 solid crust. In other words, it treats of the present condition 

 and past history of the earth ; of its progressive evolution or 

 development from its earliest condition up to the present. It 

 undertakes to determine the processes that have operated to 

 effect the earth's progressive development, where and how 

 they have acted, and the various ways in which this operation 

 has manifested itself in the character of the earth's surface. 

 It determines the various ways in which these forces have 

 written the story of their action — the various languages used, 

 so to speak. In short, it is a study of nature's method of 

 recording occurrences and the application of this knowledge 



