100 



YEARBOOK, PUBLIC MUSEUM, MILWAUKEE 



[Vol. II. 



reached and the canyon becomes V-shaped. The so-called granite of 

 the Granite Gorge is, in reality, an entirely different type of rock, being 

 a mica schist, a metamorphic rock produced by the alteration of other 

 rock forms. It is composed almost entirely of shining particles of white 

 mica, which show very brilliantly in the walls of the canyon wherever 

 the rocks have been broken. In many places the rock has been intruded 



Fig. 56. — MommKiU oi Tcipcat^ t.andstone, Monument 

 Can>on, Grand Canyon. 



by a vein or irregular injection of a pinkish granite, and in this lower 

 gorge one finds some of the most beautiful of the rock exposures in 

 the canyon. 



After many turns, the mouth of the creek is reached. It has built 

 up a broad area of sand, through which it joins the yellowish waters 

 of the Colorado just beyond. A great pile of boulders here blocks the 



