4O Granite. 



rocks never rose to the surface in a melted state, and 

 overflowed like lava streams. This and their frequently 



FIG. 10. 



A, vein of granite ; B, gneissic contorted mica-schist. The ramify- 

 ing white spaces are white quartz. Milldam Goatfell, Brodick, 

 Arran. 



largely crystalline structure, together with peculiarities 

 of crystallisation showing the presence of moisture, and 



FIG. 11. 



1. Granitic mass with injected veins among gneissic rocks. 



2. Gneiss, metamorphosed strata. 



also the transformations effected on the adjoining strata, 

 prove the granitic rocks to have cooled and consolidated 

 deep beneath the surface. 



A third division, or sub-class, is known as meta- 

 morphic rocks. All strata as they assume a solid form 

 become to a certain extent altered ; for originally they 

 were loose sediments of mud, sand, gravel, carbonate of 

 lime, or mixtures of these. When these were accumulated, 

 bed upon bed, till thousands of feet were piled one upon 



