ON TIIK 



ORIGIN, &c. 



(To the Editors of the Annals of Philosophy.) 

 GENTLEMEN, Trinity College, Cambridge, March 11, 1825. 



The existence of widely extended masses of incoherent mate- 

 rials separating the vegetable soil from the solid strata of the 

 earth, is a fact which forces itself upon the attention of every 

 practical geologist. These materials have for many years been 

 divided into two classes. The first composed of a series of 

 deposits originating in such causes as are now in daily action. 

 The second composed of various materials irregularly heaped 

 together, often transported from considerable distances, and 

 supposed to have originated in some great irregular inundation. 

 Since the publication of Cuvier's great work on fossil quadru- 

 peds, this distinction has been very generally admitted ; espe- 

 cially as it seemed to be completely borne out by the zoological 

 phenomena exhibited by the two separate classes of deposits. 



Prof. Buckland was, I believe, the first geologist who adopted 

 the terms diluvium and alluvium, diluvial detritus and post* 

 diluvial detritus to designate the two classes of phenomena 

 above alluded to. The propriety of this separation has been 

 since confirmed by a long series of well-conducted observations; 

 and by the interesting discoveries brought to light by the same 

 author within the last four years, some important errors have 

 been corrected, and the whole subject has assumed a form and 

 a consistency which it unquestionably never had before. Since 

 the publication of the " Reliquiae Diluvianao," many objections 

 have been urged against the opinions advanced in that work. 

 The greater part of the objectors are undeserving of any animad- 

 version, as they appear entirely ignorant of the very elements of 

 geology, and far too imperfectly acquainted with the facts about 

 which they write to have it in their power to turn them to any 



