180 FOSSILS. 



of nature, and of those which deprived them of their 

 being. The imperfect manner in which our know- 

 ledge can be acquired, at this source, will be seen 

 presently ; but I by no means profess to enter at 

 length into this enquiry ; I write for two purposes, 

 first and chiefly to present an explanation of the 

 manner in which our fossils received their present 

 situation, the time of that occurrence, and a reason 

 of their differences ; secondly, I write to excite dis- 

 cussion, and, having in view so desirable an object, 

 I omit intentionally the very many arguments I may 

 have to adduce at that time. In this subject argu- 

 ments and theories are plentiful, facts are scarce, and 

 we shall only increase our knowledge by the con- 

 joined labours of naturalists in every part of the 

 world ; by the diligence of collectors, and the indus- 

 try of contributors to the common stock of informa- 

 tion. I shall now proceed to mention such of the 

 ascertained facts respecting the strata of the earth, 

 and the contained fossils, as seem fit to precede the 

 more immediate object of this paper, premising, 

 however, that the amount of ignorance far exceeds 

 the amount of knowledge in this subject; and that, 

 as regards myself, I have not been able to arrive at 

 one conclusion on those points concerning which 

 philosophers have advocated such very different and 

 even opposite opinions ; for it is in vain that we read 

 books or study it theoretically, nothing but the 

 positive investigation of phenomena will ever advance 

 the study beyond the state in which it is now placed 

 by the labours of the greatest naturalist that ever 

 lived ; or warrant the adoption of one conclusion in it. 

 The study of Geology might be divided, for the 

 sake of convenience, into those strata not containing 

 organic remains, and those which do contain them. 

 The former of these comprise the rocks which were 

 in existence before the creation of plants and ani- 

 mals, and called "primitive,*' and those formations 

 called " alluvial," or such as have been in a constant 

 state of increase from existing causes up to this time, 



