38 THE COMING [CH. 



II. The destruction of former rocks, and their reproduction 

 under another form. 



III. The production of rocks de novo upon the earth's surface. 



Geologists have usually had recourse for the explanation of 

 these changes to the supposition of sundry violent and extra- 

 ordinary catastrophes, cataclysms, or general revolutions having 

 occurred in the physical state of the earth's surface. 



As the idea imparted by the term Cataclysm, Catastrophe, 

 or Revolution, is extremely vague, and may comprehend any thing 

 you choose to imagine, it answers for the time very well as an 

 explanation ; that is, it stops further inquiry. But it has also the 

 disadvantage of effectually stopping the advance of science, by 

 involving it in obscurity and confusion. 



If, however, in lieu of forming guesses as to what may have 

 been the possible causes and nature of these changes, we pursue 

 that, which I conceive the only legitimate path of geological 

 inquiry, and begin by examining the laws of nature which are 

 actually in force, we cannot but perceive that numerous physical 

 phenomena are going on at this moment on the surface of the 

 globe, by which various changes are produced in its constitution 

 and external characters; changes extremely analogous to those 

 of earlier date, whose nature is the main object of geological 

 inquiry. 



These processes are principally, 



I. The Atmospheric phenomena. 



II. The laws of the circulation and residence of Water on 

 the exterior of the globe. 



III. The action of Volcanos and Earthquakes. 



The changes effected before our eyes, by the operation of these 

 causes, in the constitution of the crust of the earth are chiefly 



L The Destruction of Rocks. 

 II. The Reproduction of others. 



