PALiEOZOIO ROOKS. 363 



cailon, existed in the granite ridge before the Mmestones were deposited. 

 On the west of tliis depression, between Little Cottonwood and American 

 Fork, the east face of the cross-spur is formed partly of Ogden Quartzite 

 and partly of the Ute limestone, continued to the westward by the under- 

 lying Cambrian slates and quartzites, all these beds standing at high and 

 varying angles, and being much broken and contorted, as they come just 

 in the apex of the great bend of the whole formation over the eastern point 

 of the lower Cottonwood granite body. 



The most distirict and char.icteristic section, however, is seen on 

 the eastern continuation of the Twin Peak Ridge, opposite Alta, locally 

 known as Emma Hill, where the erosion of the canon has cut the forma- 

 tion at an oblique angle, its strike being northwest, while the ridge 

 runs nearly east and west. Owing to the obliqueness of the section, the 

 crumplings within the beds and over the protrusions of granite appear dis- 

 torted, so that the prevailing dip of 45° northeast is frequently seen to 

 steepen to 60° and more, and again to be as low as 30°. The contact-line 

 of the granite body, on the north wall of the canon below Alta, can be 

 traced with the greatest distinctness, sloping irregularly to the eastward. 

 The ends of a series of darker slates are seen to form the summit of the 

 ridge, while along the contact to the bottom of the canon a higher series of 

 whitish quartzites, more or less iron-stained, follow in wavy curves the sur- 

 face of granite. Above these are darker-colored siliceous slates, like the 

 former dipping at 60° and over, near the bottom of the canon, and forming 

 the upper 2,000 feet of the Cambrian body. 



The Ute limestone projects out into the canon, forming a precipitous 

 spur half a mile below Alta, conspicuous by the cloudings of blue through 

 its white mass. It is a semi-crystalline limestone, more or less siliceous, 

 which, at times, becomes a quartzite, with a slight percentage of lime. 

 It is very fine-grained, but, under the microscope, shows a distinctly 

 crystalline structure, while small, rounded grains of quartz are seen to be 

 disseminated through the mass ; besides the quartz are many slender, 

 needle-like, colorless crystals, which become brown under crossed nicols, 

 and which resemble tremolite. The slates under this limestone should 

 correspond to those in which are found, in other parts of this region, the 



