90 GEOLOGY. 



CHAPTER X. 



PEESENT CHANGES IN THE EARTH. 



171. Ages of the Earth. The earth is older than 6000 

 years, as has been absolutely demonstrated by the re- 

 searches of geologists. Here is an apparent discrepancy 

 between what is revealed by the works of God and his 

 written revelation; but it is only apparent. I shall 

 speak of this point particularly in another place, and let 

 it now suffice to say that it is the belief of most geolo- 

 gists that the days of Moses represent long ages, and 

 that the time which has elapsed since the earth was 

 finally fitted for man is a very small period compared 

 with the length of time expended by the Creator in its 

 construction and preparation. It is my intention, in this 

 chapter, to treat of those changes which are matter of 

 observation and history. The word present, in the title 

 of the chapter, refers to the whole time in which man 

 has inhabited the earth, in distinction from the long pe- 

 riods consumed in its preparation for his use. It is not 

 always easy to make this distinction, and some changes 

 will be noticed in this chapter which began far back of 

 the age of man. This is necessary, because the same 

 agents which prepared the world for its present purpose 

 have produced all the changes since man was introduced 

 upon the scene. 



172. Agents of Change. The agents by which changes 

 are constantly produced in the earth are heat, water, air, 

 chemical processes, attraction, electricity, and life, both 

 vegetable and animal. The manner in which they act 

 will be developed as we proceed, and therefore I will 

 not dwell on this subject here, but will only notice in a 

 few words the principal of these agents. Water and air 

 are every where kept in motion by the influence of heat 



