THE PROBLEMS OF GEOLOGY 6oi 



which are important, and the determination of the order of their 

 consideration. 



No one, I think, can hold that any of the points of view above 

 mentioned — process, energy, agent, and result — is unimportant in a 

 general treatment of the subject of geology. It is therefore clear 

 that all these points of view must be handled. There may be differ- 

 ence of opinion as to the order in which they shall be presented; and 

 for different parts of the subject of geology and for different purposes 

 the best order will vary. 



We are now in a position to foresee the future development of 

 the science of geology. The early papers and text-books were con- 

 tent to tell of accomplished results. Almost nothing was said with 

 reference to processes. As the science developed, there crept into the 

 literature of the subject more and more reference to processes. The 

 present year a text-book of geology by Chamberlin and Salisbury has 

 appeared, the first which avowedly attempts to treat geology from the 

 point of view of processes rather than phenomena.^ This is a great 

 step in advance. But a large part of the task of reducing the pro- 

 cesses to order in terms of energies, agents, and results still remains 

 to be done. When this is accomplished, we shall have a statement of 

 the principles of geology in terms of physics and chemistry. 



How knowledge of processes has developed. — The principles of 

 geology have been developed in the past and will continue to be 

 developed in the future both from the study of processes now in 

 operation and by the consideration of the results of processes which 

 cannot be observed. An excellent illustration of a branch of geology, 

 the principles of which have largely been established by the observa- 

 tion of processes now in operation, is furnished by physiography. 

 So far as one can see, the surface of the land is now being modified 

 by the energies and agents of geology as rapidly as at any time in the 

 past. These energies and agents may have varied in their efficiency 

 from time to time and place to place, but the above statement is 

 broadly true. There are other branches of geology, the principles of 

 which have been mainly developed from results accomplished rather 

 than from observation of the present actions of energies and agents. 



I Chamberlin and Salisbury, Geology, Vol. I, "Processes and Their Results," 

 1904. 



