210 ON THE REVOLUTIONS 



ing to solid rocks, I have derived from rents formed by inequa- 

 lities of elevation, and the opening of rents upwards. Another 

 class, formed in alluvial districts, has been traced to modifi- 

 cations performed by various obstacles upon the depositions 

 made by the great inundations alluded to. 



In thus controverting some of the collateral opinions of Dr 

 HuTTON and Mr Playfair, I venture to hope that my argu- 

 ments, which have been founded on their principles, and which 

 have led me to acquiesce in their most general and important 

 conclusions, may tend less to weaken, than to confirm, the re- 

 sult of their immortal labours. 



SPECIMENS. 



