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On Diluvial Formations. By Professor Sedgwick. 

 (To the Editors of the Annals of Philosophy.) 

 GENTLEMEN, Trinity College, Cambridge, May, 1825. 



The following remarks on certain diluvial deposits form a 

 supplement to a paper which yon did me the honour to publish 

 in the Annals of Philosophy for the month of April. Circum- 

 stances, over which I have had no control, have prevented me 

 from resuming the subject sooner; but I venture to hope that 

 the statements which are now offered for insertion in vour jouj^ 

 nal, will be found sufficient to explain and vindicate the opinions 

 advanced in my former communication. 



I have the honour to be, Gentlemen, 

 Your most faithful servant, 



A. Sedgwick. 



Separation of Alluvial and Diluvial Formations. 

 In my former paper on the origin of alluvial and diluvial 

 formations, I endeavoured to explain the nature of the evidence 

 on which the two classes of deposits had been separated from 

 each other; and I also endeavoured to show, that diluvial forma- 

 tions have not originated in a succession of partial and transient 

 inundations occasioned by the bursting of lakes, or by the ordi- 

 nary operation of any cause with which we are acquainted. The 

 last conclusion might, perhaps, be established by showing the 

 constant order in the position of the two deposits, and the differ- 

 ent suites of organic remains contained in them. It derives 

 however, its most direct support from the two following consi- 

 derations : l.That, with very limited exceptions, the earth's 

 surface exhibits no traces of ancient lakes capable of producing 

 any portion of the superficial gravel. 2 That admitting 



