586 HISTORY OF GEOLOGY. 



The main points really affecting the progress of sound theoretical 

 geology,. will find a place in one of the two next Sections. 



[2nd Ed.] [I think I do no injustice to Dr. Hutton in describing his 

 theory of the earth as premature. Prof. Playfair's elegant work, Illus- 

 trations of the Huttonian Theory, (1802,) so justly admired, contains 

 many doctrines which the more mature geology of modern times rejects; 

 such as the igneous origin of chalk-flints, siliceous pudding stone, and the 

 like; the universal formation of river-beds by the rivers themselves; and 

 other points. With regard to this last-mentioned question, I think all 

 wbo have read Deluc's Geologic (1810) will deem his refutation of Play- 

 fair complete. 



But though Hutton's theory was premature, as well as Werner's, 

 the former had a far greater value as an important step on the road to 

 truth. Many of its boldest hypotheses and generalizations have become 

 a part of the general creed of geologists ; and its publication is perhaps 

 the greatest event which has yet occurred in the progress of Physical 

 Geology.] 



CHAPTER VIII. 

 THE Two ANTAGONIST DOCTRINES OF GEOLOGY. 



Sect. 1. Of the Doctrine of Geological Catastrophes. 



THAT great changes, of a kind and intensity quite different from the 

 common course of events, and which may therefore properly be 

 called catastrophes, have taken place upon the earth's surface, was an 

 opinion which appeared to be forced upon men by obvious facts. Re- 

 jecting, as a mere play of fancy, the notions of the destruction of the 

 earth by cataclysms or conflagrations, of which we have already spoken, 

 we find that the first really scientific examination of the materials of 

 the earth, that of the Sub-Apennine hills, led men to draw this inference. 

 Leonardo da Vinci, whom we have already noticed for his early and 

 strenuous assertion of the real marine origin of fossil impressions of shells, 

 also maintained that the bottom of the sea had become the top of the 

 mountain ; yet his mode of explaining this may perhaps be claimed 

 bv the modern advocates of uniform causes as more allied to their 



