222 GUIDEBOOK OF THE WESTERN UNITED STATES. 



Where the Green River formation is first seen it dips to the north 

 (right) 25° or 30°, but beyond the curve to the right, above the 

 abandoned station of Tucker, on the old line, the beds are somewhat 

 disturbed, and between mileposts 663 and 664 they are thrown into 

 a well-marked synclinal fold, which may be seen on the right. 



The siding of Detour marks the junction of the old and new lines 

 and also the termination of this narrow part of the valley. Below 

 Detour the valley is more open, at least as far as Narrows siding, 

 where it is again constricted by the appearance of harder rocks. 



Immediately below Narrows siding the lowest beds of the Green 

 River formation rise downstream, and half a mile beyond milepost 

 672 the red beds of the Wasatch make their appearance beneath the 

 gray beds of the Green River. The Wasatch is bright red, and the 

 change in color is very striking. This outcrop of the Wasatch is 

 very different in composition from that east of Soldier Summit. 

 There it is generally clay or soft shale; here it is largely a mass of 

 conglomerate composed of boulders of all sorts of rock that occur 

 in the Wasatch Mountains. The presence of such masses of con- 

 glomerate made up of boulders of this size is a sure indication that 

 the material was derived from high mountains and that it was not 

 carried far by the streams before it was dropped to form great 

 boulder beds that now are consolidated into massive rock. It there- 

 fore seems certain that a high range of mountains once existed in 

 this region when the Wasatch formation was deposited in the early 

 stages of the Tertiary period. This range must have been old as 

 measured by the standard in this mountain region, whereas the 

 present Wasatch Range is supposed to be comparatively young. 

 These statements, however, are not so contradictory as they appear, 

 for most mountain ranges have a complex historv^, involving many 

 movements up and down, and the Wasatch may not be an exception. 

 It may have had its beginning as a mountain range in early geologic 

 time, but that old range may have been worn down to a rolling plain 

 and later it may have been uplifted into a range like the present 

 Wasatch. In fact, such changes may have occurred several times. 



The conglomerate has been a formidable barrier in the pathway 

 of the stream, and it therefore forms a canyon which is scarcely 

 wider than the stream that occupies it and which has given rise to 

 the name " Narrows " for the siding at its upper end. The con- 

 glomerate is 700 or 800 feet thick and forms the sides of the valley 

 for several miles. The character of the rock, as well as its brilliant red 

 color, gives to the canyon an individuality that distinguishes it from 

 all the other canyons on the line. 



Soldier Creek flows directly west, and the railroad takes a course 

 toward a high mountain peak, one of the southern points of thei 



