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II. Kinds of Rock. 



1. Calcareous. 



Limestone; magnesium limestone; chalk; marble. 



2. Silicious. 



Sandstone dull, gray, brown, brownish-red and red. 



3. Conglomerates. 



Mass of smooth, rounded fragments, cemented in a matrix; lime- 

 stone, shell, quartz-pebble, granite-pebble, and volcanic con- 

 glomerates. 



4. Shale. 



Shale consolidated fine sand, mud or clay; color, gray, yellowish, 

 brown or black. Black most common, due to organic remains 

 of animals and plants. 



5. Argillaceous Sandstone. 



Consolidated clayey beds of sandstone, which usually break into 

 thin slabs, flagstones for sidewalks. 



6. Slate. 



Structure fine and firmer than shale. Splits easily and evenly. 

 Used for roofing. 



7. Granite. 



Composition quartz, feldspar, mica, mixed promiscuously to- 

 gether. Quartz, grayish or smoky in color, no cleavage; feld- 

 spar white or flesh-red, good cleavage, sparkling faces in sun; 

 mica white, brownish or black, perfect cleavage; quartz and 

 feldspar hard mica soft. 



8. Gneiss. 



Same constituents as granite, Jbut arranged in planes; owing to 

 cleavage of mica, rock splits into layers. 



9. Mica Schist. 



Constituents same as granite and gneiss mica and quartz most 

 abundant; divides into thin layers. No dividing line bafc 

 granite, gneiss and mica schist. 



10. Syenite. 



Granite-lick rock, mica replaced by hornblend; little or no quartz: 



1.1. Trap, Basalt, Lavas or Volcanic Rocks. 

 Igneous rocks, cooled from fusion. 



III. Structure of Rocks. 



1. Stratified Rock layers piled one upon another. 



(a) Sandstone. 



(b) Limestone. 



(c) Shale. 



(d) Slate. 



