GRAND CANON SECTION. 61 



No. 1 3, 400 feet. Thinly bedded, bluish limestone, with intercalated, 

 thinly bedded sandstones and clay shales below. The limestones are con- 

 cretionary and brecciated, and have many cavities filled with calcspar. 



No. 14, 100 feet. Greenish, micaceous shales, with beds of gray and 

 brown sandstone, containing iron concretions. 



TONTO GEOUP. 



No. 15, 75 feet. Limestones; a good marble; often mottled; some- 

 times containing concretions of chert. 



No. 1G, GOO feet. Rust colored sandstones ; thinly bedded ; indurated; 

 reenish above. 



No. 17, 100 feet. Brown sandstone. 





* * * 



UINTA GEOUP. 



The Uinta Mountains are chiefly composed of Uinta Sandstone. The 

 western end of this range where it abuts against the Wasatch Ranor-e, I 



o O O / 



have not carefully studied; but to the eastward the broad, massive range is 

 a grand sandstone structure. Other groups are turned up on their flanks, 

 and in Red Creek Caiion a lower group is seen. On the southeast margin 

 of the range a line of peaks may be seen extending across the Canon of 

 Lodore, composed of groups of Red Wall Limestone. 



In the many deep canons and gulches by which the range is cleft, in 

 the many amphitheaters that are found along the crest of the range, and in 

 the mural faces of its lofty peaks, everywhere the sandstones are made bare 

 to the eye of the geologist; but the best sections can be made along the 

 canons. In a subsequent chapter some of these sections will be given. 



GEAND CANON GEOUP. 



This group is exposed in the great southern bends of the Grand Canon, 

 where the Colorado River passes the end of the Kaibab Plateau. The best 



* 



exposure can be seen about ten miles below the mouth of the Little Colo- 

 rado. Many of the lateral streams coming in from the west and north cut 

 through this group and afford fine exposures. The best one probably is in 



