Silt. "The more comminuted sand, clay and earth, which is trans- 

 ported by running water." 



Simple Minerals, are composed of a single mineral substance. Rocks 

 are generally aggregates of several simple minerals cemented to- 

 gether. 



Slate. A reck dividing into thin layers. 



Stalactite. Concreted carbonate of lime, hanging from the roofs of 

 caves, and like icicles in form. 



Stalagmites. Crusts and irregular shaped masses of concreted car- 

 bonate of lime, formed on the floors of caves, by deposits from the 

 dripping of water. 



Stratification. An arrangement of rocks in strata. 



Strata. Layers of rock parallel to each other. 



Stratum. A layer of rocks; one of the strata. 



Strike. Tho direction in which the edges of strata crop out. It is 

 synonymous with lino of bearing. 



Syenite and Sienite. A granite rock in which hornblende replaces 

 the mica. 



Synclinal line and Synclinal Axis. When the strata dip downward 

 in opposite directions, like the sides of a gutter. 



Tulius. In geology, a sloping heap of broken rocks and stones at 

 the foot of many cliffs. 



Tertiary Strata. "A series of sedimentary rocks, with characters 

 which distinguish them from two other great series of strata — the sec- 

 ondary and primary — which lie beneath them." 



Teatacea. "Molluscous animals, having a shelly covering." 



Tepid. Warm. 



Thermal. Hot. 



Thin out. Strata which diminish in thickness until they disappear, 

 are said U> thin out. 



Trap — Trappean Rocks. Ancient volcanic rocks, composed of 

 feldspar, hornblende and augite. Basalt, greenstone, amygdaloid and 

 dolomite, are trap rocks. 



Travertin. "A concretionary limestone, hard and serai-crystalline, 

 deposited from the water of springs." • 



Tufa Calcareous. "A porous rock, deposited by calcareous waters 



