Principles of Geology and its Aim. 275 



Now, whenever a geologist sees the results of some great 

 force and those results are similar to the phenomena produced 

 by glaciers, he concludes that at some previous time the con- 

 ditions were such as to make it possible for glaciers to exist in 

 the locality in which his observations were made, for no other 



rce could produce them. 



2 He reasons that all affects must be referred to secondary causes. 



i other words, law governs all phenomena, and forces are so 

 balanced as to produce all known and unknown phenomena. 

 All events that have transpired in the development and con- 

 figuration of the earth have been brought about by law. In 

 the formation of glaciers certain laws are obeyed, and those 

 iws are always obeyed unless an equilibrium is sustained be- 

 veen them and some other laws are overbalanced. 



When the conditions are favorable for the action of glacial 

 laws glaciers will be found. The same principle holds good 

 in the distribution of life. 



3. The forces in existence to-day are capable of producing all 

 phenomena that have and may occur. Therefore, the geologist 

 must study the methods by which they are producing changes 

 at present, and thereby be able to judge of what took place 

 ages ago, and the manner in which great events trans- 

 pired. In other words, the past is understood by the present 

 and to some extent the future may also be understood. No new 

 law is, nor has been, necessary for the explanation of phe- 

 nomena and, therefore, there have been no accidental happen- 

 ings. There may be laws that man has not as yet learned the 

 nature of, and they may be so balanced as to be beyond man's 

 comprehension, but that there are being or have been created 

 new laws, and that there are accidents, the geologist does not 

 admit. 



4. The earth is undergoing and therefore has undergone changes. 

 He sees this in studying the phenomena of denudation and 

 disintegration. He sees that the mountains are being de- 

 stroyed by chemical and physical agencies, and that they are 

 being gradually carried into the valleys, and then into the 

 sea. This, he reasons, must have been going on ever since the 

 first continent made its apppearance. 



