CHAPTER III. 



DYNAMICAL GEOLOGY. 



TN the days of the Greek philosophers attention had been 

 frequently directed to the changes in the surface conformation 

 of the earth, and the natural forces which produce them. 

 Herodotus, Aristotle, Strabo, Seneca, Pliny, and others con- 

 tributed valuable information regarding wind and weather, 

 springs, water-courses, inundations, and earthquakes. A sys- 

 tematic treatment of these agencies, with reference to the 

 changes produced in the earth's surface, was first carried out 

 by the Belgian mathematician, Simon Stevin (1548-1620). 

 But it was not until two centuries later, after the physical 

 investigation of the earth's surface had been conducted along 

 scientific lines, and had shown the influence of these agents 

 upon the existing conformation of the earth's surface, that 

 geologists began to correlate the past changes in the earth's 

 surface with similar natural causes. Then dynamical geology 

 gradually developed as a branch of study intermediate between 

 geography and geoldgy, which was fostered from both sides, 

 and proved useful to geography in so far as it elucidated the 

 present constitution of the earth's surface, to geology in so far 

 as it served t) explain the successive phases in the earlier 

 ages. 



Hutton and Playfair had expressed the view that all earlier 

 geological events were explicable upon the basis of the forces 

 and phenomena still in action. The Scottish geologists had 

 pointed out the importance of realising the high antiquity of 

 our earth, and the gigantic work that might be accomplished 

 by physical agencies small in themselves but acting throughout 

 long periods of time. The fame and authority of the great 

 Frenchmen, Buffon and Cuvier, lent support, on the other 

 hand, to the conception of repeated earth catastrophes. 

 Approaching the subject, as they did, from the standpoint of 



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