THE OVEELAND ROUTE 



FRANCISCO 



159 



/ 



water level of old Lake Bonneville lay somewhere near Montello, at 

 an elevation of about 5,000 feet, probably just above the town, but 

 no distinct traces of tlie old water line can be seen from the train. 

 Looking back or down across the valley (southward), the traveler may 

 sec Pilot Peak; the highest point at the south end of the Pilot Range. 

 Banvard (elevation, 4,976 feet), Noble (5,117 feet), UUin (5,256 fee't), 

 Tioga (5,597 feet), and Omar (5,6i0 feet), passed in the order named, 

 are mere sidetracks or minor stations. 



The surface material of the valley is mostly a light-colored clay 

 mingled with pebbles and fragments of rock. The fragments include 

 many of hght-gray limestone, evidently representing rock that is 

 exposed in the adjacent mountains. The valley is covered with a 

 fairly uniform growth of brush, and the sparse grass which in less 

 arid regions would hardly be noticed affords good grazing for stock. 

 The mountains appear smooth and rounded as seen from a distance 

 and are in part covered with a scanty growth of cedare. ' 



Just beyond Tioga, a sidetrack and signboard near milepost 653, 



the raiboad reaches the head of the open valley. Bedrock projects 



in many places, and ridn;es of rock extend down from the mountain 



id. These are limestones and 

 lar rocks show as ruo^orpd odoros 



ailro 



quartzites of Carboniferous age. 

 on the more distant mountains to the south. In the reports of The 

 Fortieth Parallel Survey the pass through which the railroad climbs 

 was named Toano Pass, and the mountains to the south were called 

 the Gosiute Range and those to the north the Toano Mountains. A 

 large part of the high country for a long distance beyond Toano Pass 

 is made up of Carboniferous sediments. Phosphate rock is reported 

 to have been found in these rocks in the same relative position as in the 

 great phosphate fields of southern Idaho and vicinity, but in Nevada 

 the beds^ so far as known, are too thin to be of commercial value. 



From the upper end of Toancf Pass, near milepost 649, may be seen 

 in the valleys on both sides beds that are conspicuously exposed as 

 chalky- white cliffs or as bare white patches on the rolling plains or on 

 low ridges. These beds are composed mainly of friable gray, white, 



tnv places containinsr 



w 



panied lava (rhyolitic) eruptions. 



limestone, at m 

 material, chiefly the tuff or ash 



» 



rocks 



areas 



^ The Humboldt formation was de- 

 scribed by Clarence King in 1878 as the 

 deposit of a great lake "vrhich he thought 

 had occupied most of the territorj^ from 

 the Wasatch Mountains in Utah to the 

 Sierra Nevada, in Pliocene time. He 

 named this hypothetical body of water 

 Shoshone Lake, and these sediments, 

 which he supposed had been laid down 



in its water, he called the *' Humboldt 



series. 



j» 



Durino; recent vears little atten 



tion has been given to the further study 

 of this formation, but geologists of the 

 present day are much inclined to doubt 

 the existence of the extensive lake thus 

 conjectured, as well as the necessity for 

 assuming that these beds as a whole were 

 lake deposits. 



