p^^j^j GEOLOGY SECTION NO. 18. 233 



83. Light reddish-gray sandstone, with red shaly bands. At the top 



there is about one foot of pink sanrlstone ; 6 feet. 



84. Sandstone with brown and red lines, general color reddish brown, 



dark below, 6 feet. 



85. Yellowish-brown laminated sandstone, very hard and compact, 



almost quartzitic, breaking into laminae from one-eighth of an 

 inch to 2 or 3 inches in thickuess, 6 feet. 

 8Q. Gray sandstone, somewhat laminated at the top ; weathering of a 

 rusty brown ; 20 feet. 



87. Brown laminated sandstone, with green coating between the laminae, 



2 feet. 



88. Light brown sandstone, with bands of white quartzite varying in 



thickuess from four inches to a foot ; the thickest at the top ; 6 

 feet. 



89. Brown quartzitic sandstone in laminae of about 18 inches each, 6 



feet. 



90. White quartzite, 4 feet. 



91. Brown quartzitic sandstone, 2 feet. 



92. White quartzite, (about 2 feet from the bottom there is a layer of 



brown sandstone 6 inches thick,) 5 feet. 



93. Brown quartzitic sandstone, 2 feet. 



94. White quartzite, 5 feet. 



95. Brown quartzitic sandstone, 5 feet. 



96. White quartzite, 20 feet. 



97. Brown quartzite, 10 feet. 



i 98. Granite, coarse, and rose-colored. 



This bed (98) reaches to the bottom of the canon at the bead of the 

 creek under Horseshoe Mountain. The section from bed 1 to 20 is made 

 on the line a &, Fig. 1., Plate IX. From bed 24 to bed 67, inclusive, it 

 is made between the points e and h in the illustration ; while the remain- 

 der of the section (68 to 98) is made on the line marked h i. In the top 

 of bed 23 of the section given above we have fragments of the sandstone 

 of No. 22 caught in the mass; and again we see the volcanic rock pene- 

 trating the sandstones, and their interlaminated shales changing their 

 character very much. Mr. Holmes sketched several of these intrusive 

 masses, which are beautifully shown in Figs. 1 and 2, Plate X. The 

 lower beds in the section given above dip at an angle of about 10 to 15 

 degrees. The quartzites and magnesian limestones in the last part of 

 the section are the same that are given in the first part on the east side 

 of the fault. 



It is a question whether or not the sandstones of No. 22 of this sec- 

 tion (No. 18) are the same as No. 24, or whether they belong to a higher 

 horizon, and have been mer'ely separated by the intrusion of No. 23. I 

 incline to the latter. The character of the sandstone in both places is 

 similar, but in No. 24 there is very little difierence between the top and 

 the bottom layers. The difference is no greater than between No. 22 and 

 the top of 24. If 22 is merely the continuation of 24 tolded, the euds of 

 the two probably connect below the surface. The rock of No. 23 is pe- 

 culiar. It is trachytic» and very highly siliceous. It is very white, and 

 might, if seen alone and not verj^ carefully examined, be mistaken for a 

 highly-metamorphosed sandstone. A closer examination reveals the 

 presence of crystals of feldspar. The large proportion of silica is due, 

 perhaps, to the intrusion among the sandstones, from which it was, in 

 great measure, derived. 



As seen in the illustration, Plate IX, Fig. 1 at c, bed 22 dips about 

 30°, while No. 24, at e in the illustration, dips about 15°. 



