GLOSSARY. 



and has often a regular columnar form. The Palisades of the 

 Hudson show the columnar aspect of trap rocks. The Giant's 

 Causeway is cited as an example of basaltic rocks, and the col- 

 umnar structure is there very strikingly displayed. 



Bitumen. Mineral pitch, which is often seen to ooze from 

 fossil coal when on fire. 



Bituminous Shale. A slaty rock, containing bitumen, and 

 which occurs in the coal measures- 



Blende. Sulphuret of zinc. A common shining zinc ore. 



Bluffs. High banks of earth or rock, with a steep front. The 

 term is generally applied to high banks forming the boundaries 

 of a river, or river alluvions. 



Botryoidal. Resembling a bunch of grapes in form. 



Boulders. Rocks which have been transported from a dis- 

 tance, and more or less rounded by attrition or the action of the 

 weather. They lie upon the surface or loose in the soil, and 

 generally differ from the underlying rock in the neighbourhood. 



Breccia. A rock composed of angular fragments, cemented to- 

 gether by lime or other substances. 



C. 



Calc Sinter, A German term for depositions of limestone from 

 springs, and waters which contain this mineral in solution. 



Calcareous rock. A term synonymous with limestones. 



Calcareous Spar. Crystallized carbonate of lime. 



Carbon. The combustible element of coal. 



Carbonates. Chemical compounds containing carbonic acid, 

 which is composed of oxygen and carbon. 



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

 porting combustion, and deleterious to animal life. It is com- 

 mon in caves and wells, and many incautious persons lose their 

 lives in consequence of descending without first ascertaining its 

 presence by letting down a lighted candle. Man cannot live 

 where a candle will not burn freely. 



Carboniferous. Coal-bearing rocks. This term has been ap- 

 plied to a formation belonging to an ancient group of secondary 

 rocks which contains coal. The term is now used in a more 

 enlarged sense, and may be applied to any rocks containing coal. 



Chert. A silicious mineral, approaching to chalcedony, flint, 

 and hornstone. It is usually found in limestone. 



Chlorite. A soft green scaly mineral, slightly unctuous. 



Chloritic Slate. Slate containing chlorite. 



Clinkstone. A slaty feldspathic or basaltic rock, which is so- 

 norous when struck. 



Cleavage. The separation of the laminae of rocks and min- 

 erals in certain constant directions. They are not always 

 parallel to the planes of stratification, but are oft en mistaken for 

 them. 



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