INTRODUCTION. 



The superficial crust of the Globe, as far as it has hitherto 

 been exposed to observation, in the various sections afforded 

 by deep mines, sea clilfs, or by valleys and mountainous 

 regions, is foimd to consist of certain layers or strata, 

 differently composed, and arranged in a certain order as 

 regards each other. The composition of these mineral 

 masses, the position which they occupy, the changes they 

 have imdergone, and the organic remains contained in 

 them, form the chief objects of Geological inquiry. 



An acquaintance with the collateral branches of Science, 

 Chemistry, Mineralogy, and Palaeontology, will mate- 

 rially facilitate any researches connected with the early 

 history of our globe, as by the two former we acquire a 

 knowledge of the composition, form, structure, &c., of the 

 various simple or compoimd mineral bodies, which are 

 either found, combined with or constituting the chief por- 

 tion of different rocks or strata; and Palaeontology 

 teaches us the character and relations, to existing beings, 

 of the numerous genera of Plants, Shells, and Animals, 

 which are more or less abundantly entombed in aU the 

 stratified rocks. 



The Rocks or Strata have been generally divided by 

 Geologists into two great groups ; ^iz.. Stratified, and 

 Unstratified, and these are again subdivided as 

 follows : — 



Stratified Rocks J resulting from f 



{ Aqueous agencies. [ 



Unstratified RocksJ "^"Iting from f V, 



l^ Igneous agencies. [ ^^ 



Fossiliferous. 

 Xon-fossiliferons. 



olcanic. 

 Plutonic. 



