24 NATURAL HISTORY OF 



CHANGES ON THE EARTH'S SURFACE SINCE THE 



COMMENCEMENT OF THE PRESENT 



ZOOLOGICAL SYSTEM. 



THE present superficial character of the earth may 

 "be a result of the combined action of sudden violent 

 disruptions, and long durations of gradual disintegra- 

 tions, either operating as restorers of equipoises in the 

 permanent laws of necessity, or as conductors of the 

 slow process of accumulations, which again prepare a 

 great convulsion. Taking the newer pliocene, or second 

 tertiary age, to be coincident with the mighty changes 

 of sea and shore, when volcanic disturbances were still 

 in active operation, and that convulsive state, which 

 subsequent catastrophes, and the succession of ages, 

 have as yet only reduced in number, and moderated in 

 force, when first a congenial atmosphere had begun to 

 prevail; we have an epoch which would include the 

 Mosaic deluge, and terminate with that greatest of 

 all recorded destructions ; one, moreover, supported by 

 innumerable historical confirmations ; although some 

 of these may be attributed to subsequent periods, and 

 to distinct calamities ; such as the bursting of the bar- 

 riers of great mountain lakes, and irruptions of the 

 sea. For these being confounded, in so many and 



