All Unique Region 189 



the rocks, together with the heat generated in the crust of the 

 earth by mountain-making movements and earth-warpings, 

 the mineral-bearing veins have been developed, and ore bodies 

 segregated. Chemical changes in the rocks have resulted from 

 the complex physical conditions which have prevailed within 

 the earth. When more is known about the character of the 

 interior of the earth, and the physics of the earth's crust is bet- 

 ter understood, it will be possible to more clearly interpret the 

 facts of earth. 



