488 DESCRIPTIVE GEOLOGY, 



group of limestones. The whole body has been indicated by the color 

 of the Lower Coal-Measure group; but the negative evidence of no lower 

 fossils having been found is by no means a conclusive proof that the 

 Devonian formation may not be represented at this point. The finding of 

 Silurian fossils in the limestones in the neighborhood of Egan Canon, on 

 the other hand, renders it certain that the Devonian limestones may be 

 found, if not here, somewhat to the southward. 



The range was not visited by our parties between Gosi-Ute Canon and 

 Egan Canon, which lies some 8 or 10 miles to the south of the limits of 

 the map. Here, at the point where the Overland Stage Road crosses the 

 range, it is divided by a broad, open valley into two distinct ridges. The 

 lower or western ridge is composed of limestones, dipping gently to the 

 westward, which probably represent a continuation of those seen in Gosi- 

 Ute Canon. In the eastern or higher ridge is seen a section of Cambrian 

 quartzites and slates overlying granite, also dipping to the westward. Here 

 the granite body forms the extreme eastern face of the range, and is over- 

 laid by several thousand feet of quartzites and quartzitic schists, together 

 with a 50-foot bed of finely-laminated argillite, or roofing-slate. The main 

 mass of quartzite is a compact, white, semi-translucent, thoroughly vitrified 

 rock, showing little trace of granular structure. Within the series are thin- 

 ner beds of dark-purple quartzite, showing evidence of having been sub- 

 mitted to great pressure, the surfaces being indented with impressions of 

 coarse quartz pebbles, while in the interior there are developed occasional 

 flakes of white mica. Another bed of light grayish-green rock shows a 

 more fully-developed schistose structure, and is quite full of fine plates of 

 white mica, though in hardly sufiicient quantities to constitute a normal 

 mica-schist. At the base is a bed formed of coarse rounded grains of quartz, 

 in a matrix of green semi-crystalline quartz, which also has an occasional 

 development of bronze-colored mica. 



The granite is an even-grained, easily decomposable rock, containing 

 a good deal of plagioclase, much magnesian mica, and some little horn- 

 blende, distributed in fine dust throughout the other constituents, with 

 distinctly crystallized titanites. The rock also contains the zircon-like 

 mineral which has been observed in the Archaean rocks of the Wahsatch 



