CLASSIFICATION. 



67 



under the ocean that the change of position took 

 place. No person who reflects on the appearances 

 presented in a mountainous district can believe 

 that the broken and elevated beds, the peaked sum- 

 mits, the impending cliffs, and the immense frag- 

 ments of rocks scattered in the valleys and adja- 

 cent countries, were originally created and placed 

 as we now observe them. 



CHAPTER VI. 



CLASSIFICATION OF ROCKS. 



Classification : Primary, Secondary, Transition, Tertiary. — 

 Classification of Conybeare and Philips.— Of De la Beche. — 

 Primitive Kocks described. — Mr, Lyeil's Views. — Hypogene. 

 — Division of Primary Rocks : Granite, Syenite, Felspathic, 

 &c. — Professor Hitchcock's account of Granite. — Gneiss. — ■ 

 Mica Slate. — Hornblende Rock. — Crystalline Limestone. — 

 Quartz Rock. 



We have already stated that the principal divis- 

 ion of rocks is into stratified and unstratified ; an- 

 other is into fossiliferous and non-fossiliferous ; in- 

 deed, one of the first classifications of rocks was 

 founded on the discovery that some rocks contain 

 organic remains, while others are destitute of them. 

 As the lowest series of rocks with which we are 

 acquainted give no evidence of the existence in 

 them of either vegetable or animal relics, they 

 were very naturally supposed to have been formed 

 before the creation of things that have life, and 

 were therefore called primary, or the primitive 

 class ; while those beds which contain organic re- 

 mains were called secondary. In a short time, how- 

 ever, it was perceived that an intermediate class 



