214 



Adventures in Scenery 



Spires are made of resistant massive granite. The intrusions of 

 (Bridal veil) granite are large and irregular in shape, and be- 

 cause the rock is resistant to weathering it forms the summits 

 of pinnacles and crags. 



Massive Granite Forms Lower Limit 

 of Gorge 



In the lower chamber, that is, below the portal, the jointed 

 character of the rocks enabled the ice of the glaciers to quarry 

 and remove the rocks, and thus there came to be the lower 

 chamber. The rocks forming the north and south walls of the 

 lower chamber are diversified in character. Large bodies of 

 diorite and gabbro are systematically jointed and fractured and 



Photo by G. K. Gilbert, U. S. Geol. Survey 

 FIG. 67. Well-jointed granite in the High Sierra. 



hence readily quarried and eroded. West of the jointed and 

 fractured gabbro and diorite of the lower chamber the rocks 

 consist of massive granite (El Capitan) . This rock is but 

 sparsely jointed and not readily quarriable. Here is the west- 



