GEOLOGICAL INVESTIGATION. 11 



The present duty of a systematical inquiry, is to 

 describe objects and actions which cannot all yet be 

 classed under general divisions and laws ; and it cannot 

 avoid proposing analogies and inferences which it 

 is unable to prove; while it must also make use of 

 proofs which are themselves to be proved hereafter, 

 or prove several laws by one or more facts, or the 

 reverse; thus necessarily becoming entangled among 

 future and retrospective references. Hence, the order 

 which would be desired, cannot be adopted. And 

 hence also it may be useful to give a sketch of an 

 order, which, however dry and repulsive it may appear, 

 will serve to indicate the catenation of the facts and 

 inferences. 



The materials of this inquiry are Objects and Actions ; 

 the result constitutes Inferences ; and these are retro- 

 spective, as well as present and future. The Retrospect 

 is the material for a Theory of the Earth. 



OBJECTS. 



The Objects are the MATERIALS of the Earth. 



The Materials are, ROCKS and FRAGMENTS. 



The Rocks are, STRATIFIED and UNSTRATIFIED. 



ROCKS and FRAGMENTS are formed of the same sub- 

 stances. 



The substances are simple earths, including oxydes, 

 or minerals. 



Rocks, and the larger Fragments, are composed of 

 Earths or of Minerals, and of Animal and Vegetable 

 matters compacted. 



They are compacted by Mechanical approximation, 

 or by Chemical action, or by both united. 



