on j»BBT.] SALT LAKE CITY TO GRAND JUNCTION. 397 



profoundly dislocated, the zone of faulting being a mile wide, but many 

 of the faults Ira verse the upper delta only, showing that the lake epoch, 

 like the recent epoch, witnessed mountain growth. The train, on its 

 wav from Springville to Spanish Fork canyon, climbs and crosses the 

 continent lower terrace and traverses the district of faults. 



[By s. P. Emmons. ] 



In Spanish Pork canyon the main Wasatch uplift is crossed in a 

 southeasterly direction at a point where it is much narrower than in 

 either of the transverse gorges further north. No systematic geologi- 

 cal examination of this portion of the range has yet been made, and 

 only the broader outlines of its structure can be given. 



About 6,000 feet (1,829 m.) of Upper Paleozoic beds, mainly siliceous 

 members of the Upper Carboniferous, are first crossed, which dip 25° 

 to 30° to the southeast. These form the main front range through 

 which the Spanish Fork gorge is cut. Overlying these and generally 

 with somewhat steeper dip, are conglomerates, shales, and red sand- 

 stones, presumably of Triassic age. Two streams, running in monoclinal 

 valleys eroded out of these rocks, unite to form that of Spanish Fork. 

 Beyond the junction the road bends to the south up the valley of one 

 of the streams, known as Thistle Creek. On the east side of this valley 

 are fine cliff exposures of the characteristic red sandstones of the Trias, 

 overlain by massive yellowish white sandstones, remarkable for their 

 cross-bedding and the curious forms into which they weather in the 

 overhanging cliffs. The estimated thickness of these rocks above the 

 Carboniferous is 1,000 feet (1,219 m.).™ A branch line follows this 

 valley southward to the Mormon towns in the San Fete and Sevier 

 valleys. 



The main line at Thistle bends eastward, across the strike of the beds, 

 up the valley of Soldiers' Pork. A short distance beyond this station 

 are seen the drab shales and thin-bedded limestones of the Jurassic, 

 resting in apparent conformity on the cross bedded sandstones, in 

 which, along the railroad cut, may be found Pectens and Pentacrinus 

 Asteriscus. Ascending the valley of Soldiers' Fork the upturned edges 

 of the Jurassic strata are covered by nearly horizontal beds of reddish 

 Conglomerates and coarse sandstones which, in geological position, 

 composition and manner of weathering, resemble those of the Wasatch 

 Eocene, as exposed in Echo canyon along the line of the Union Pacific 

 Railroad. After ascending for some miles past the castellated cliffs 

 formed by those conglomerates, an overlying series of light-colored cal- 

 careous marls and shales is reached, which are less massive, and proba- 

 bly represent the Creen Fiver Eocene of the Wyoming Basin, since they 

 are said to rest unconformably on the conglomerates and to overlap on 

 to the upturned Jurassic and Triassic strata nearer the mountains. 



