GLOSSARY. 
and has often :a regular columnar form. The Palisados 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 strikmgly 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. 
Ccdcareous 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 maybe 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 fo^r 
them. 
