388 



more or less roiindod by attrition or the action of the woather. They 

 lie upon the surface or loose in the soil, and generally differ from the 

 iindei lying rock in the neigh boi hood. 



Breccia. A rook composed of angular fragments, cemented together 

 by lime or other substaiices. 



Calc Sinter. A German term f(tr depiwitions of limestone from 

 springs, and waters which contain this mineral in solution. 



Calcareous Rocks. A term synonymous with limestones. 



Calcareous Spar. Crystalliz'-d carbonate of lime. 



Carbon. The combustible element of coal. 



Carbonates. Chemical compounds containing carbonic acid, -which 

 is composed of oxygen nnd caibon. 



Carbonic Acid. An acid gaseous compound, incapable of support- 

 ing combustion, and deleterious to animal life. It is c<iinmon in caves 

 and wells, and many incautious persons lose their lives in consequence of 

 descenrling, without first ascertaining its presence by Jetting down a 

 lighte<l candle. Man cannot live where a candle wi'l not burn freely. 



Carbonifernvs. Coal [)eariiig roi-ks. This term has been applied 

 to forniaiions belonging to an ancient group of secondary rocks, which 

 contains coal. Tiie term is now used in a more enlarged sense, and may 

 be applied to any rocks containing coal. 



Chalybeate. Impregnated with iron. 



Chert. A silicious mineral, f pproaching to chalcedony, flint and 

 hornstone. It is usually found in limestone. 



Chlorite. A soft green scaly mineral, slightly unctuous. 



Chloride Slate. Slate containing chlorite. 



Clinkstone. A slaty feldspathic or kualtic rock, which is sonorous 

 when struck. 



Cleavage. The separation of the laminae of rocks and minerals in 

 certain constant directions. They are not always parallel to the planes 

 of stratification, but are often mi>taken for them. 



Coal Formation. Coal Measures. These tern s are considered 

 synonymous, and refer to the great deposit of coal in the older second- 

 ary rocks, which has boen called "the independent coal formation. 

 There are, however, d^'pt)sits of carbonaceous material in all the 

 geological periods, and several of them might also be called coal for- 

 maliuus. 



