645 



PHYSICAL GEOLOGY. 



CHAPTER VII. 

 PROGRESS OF PHYSICAL GEOLOGY. 



Sect. 1. Object and Distinctions of Physical 

 Geology. 



BEING, in consequence of the steps which we 

 have attempted to describe, in possession of 

 two sciences, one of which traces the laws of action 

 of known causes, and the other describes the phe- 

 nomena which the earth's surface presents, we are 

 now prepared to examine how far the attempts to 

 refer the facts to their causes have been successful: 

 we are ready to enter upon the consideration of 

 Theoretical or Physical Geology, as, by analogy 

 with Physical Astronomy, we may term this branch 

 of speculation. 



The distinction of this from other portions of 

 our knowledge is sufficiently evident. In former 

 times, geology was always associated with mineral- 

 ogy, and sometimes confounded with it; but the 

 mistake of such an arrangement must be clear, 

 from what has been said. Geology is connected 

 with mineralogy, only so far as the latter science 

 classifies a large portion of the objects which geo- 



