INORGANIC GEOLOGICAL DYNAMICS. 597 



of Dynamics enabled philosophers to pass securely 

 and completely from Phenomenal Astronomy id 

 Physical Astronomy. 



In like manner, in order that we may advance 

 from Phenomenal Geology to Physical Geology, we 

 need a science of Geological Dynamics ; that is, a 

 science which shall investigate and determine the 

 laws and consequences of the known causes of 

 changes such as those which geology considers ; 

 and which shall do this, not in an occasional, imper- 

 fect, and unconnected manner, but by systematic, 

 complete, and conclusive methods ; shall, in short, 

 be a Science, and not a promiscuous assemblage of 

 desultory essays. 



The necessity of such a study, as a distinct 

 branch of geology, is perhaps hardly yet formally 

 recognized, although the researches which belong 

 to it have, of late years, assumed a much more 

 methodical and scientific character than they before 

 possessed. Mr. Lyell's work (Principles of Geology) 

 in particular, has eminently contributed to place 

 Geological Dynamics in its proper prominent posi- 

 tion. Of the four books of his Treatise, the second 

 and third are upon this division of the subject; 

 the second book treating of aqueous and igneous 

 causes of change, and the third, of changes in the 

 organic world. 



There is no difficulty in separating this auxiliary 

 geological science from theoretical geology itself, 

 in which we apply our principles to the explanation 



