C 173 J 



Fourth, aluminous schist, or shale, consisting of 

 ihc decomposed materials of different rocks cemented 

 by a small quantity of ferruginous or siliceous matter; 

 and often containing the impressions of vegetables. 



Fifth, calcareous sandstone, which is calcareous 

 sand, cemented by calcareous matter* 



Sixth, irone stone, formed of nearly the same ma- 

 terials ^s aluminous schist, or shale ; but containing a 

 much larger quantity of oxide or iron. 



Seventh, basalt or wbinstone, which consists of 

 feldspar and hornblende with materials derived from 

 the decomposition of the primary rocks; the crystals 

 are "generally so small as to give the rock a homo- 

 geneous appearance; and it is often disposed in very 

 regular columns, having usually five or six sides. 



Eighth, bituminous or common coal. 



Ninth, gypsum, the substance so well known by 

 that name, which consists of sulphate of lime; and of- 

 ten contains sand. 



Tenth, rock salt. 



Eleventh, chalk, which usually abounds in re- 

 mains of marine animals, and contains horizontal 

 layers of flints. 



Twelfth, plum-pudding stone, consisting of pebbles 

 cemented by a ferruginous or siliceous cement. 



To describe more particularly the constituent 

 parts of the different rocks and strata will be unneces* 

 sary; at any time, indeed, details on this subject are 

 useless, unless the specimens are examined by the 

 ; and a close inspection and comparison of the dif* 



