CLASSIFICATION OF ROCKS. 



79 



Artificial System. 



Natural 

 System. 



Series up to 

 Chalk or 



Limestone. 



Magnesian. First above the 



coal series 

 J Argillaceous. Lias, Muschel- 



kalk, &c. 

 Compact. Various ; generally 



organic 

 Oolithic. 

 Chalk. 



* Sandstone 



Red marl. Red sandstone containing 

 salt and gypsum 



White. Various, and sand. Quader- 

 sandstein, &c. 



Ferruginous, and sand 



Green, and sand 



t Shale > 



C various 



* Clay S 



Jasper, modified from * 

 Siliceous schist, modified fromf 

 Chert, modified from * 

 Salt and Gypsum considered as minerals In this class 



Class 5. 



with lig- 

 nite coal- 



UNSTRATIFIED. 



Serpentine 



Overlying 

 aud venous 

 rocks refer- 

 able in time 

 to Class 3, 

 4,5. 



As connected with Trap 



chiefly. 

 Diallage rock. 



Pitchstone. Comprising pearlstone. 

 Known only in veins. 

 f Trap. 



Indurated clay. Base of the amygda- 



loids. 

 Claystone. 



Indurated claystone. Comprising some 



so called basalts. 

 Clinkstone. 



Compact felspar. 



Basalt. Of hornblende only. 



Greenstone. 



Syenite. Sometimes emulating granite. 



Augit rock. 



Hypersthene rock. 



Porphyries. With various bases. 



Amygdaloids. 



Tuff. Of eruption, only or chiefly. 



Class 6. 



