98 



GUIDEBOOK OF THE WESTERN UNITED STATES. 



above the railroad. This is the cuhiiinating peak of the Wasatch 

 Mountains (PL XXVIII; p. 104), a range that came into existence 



acted until the stream became a stupen- 

 dous torrent. The volume of water dis- 

 charged before the flow became steady 

 was enough to supply Niagara River for 

 25 years, but the record of the torrent's 

 violence leads to the belief that it lasted 

 for a much shorter period. 



The rapid deepening of the outlet chan- 

 nel was finally checked when the stream 

 reached a sill of solid rock beneath the 

 soft alluA-ium of the pass, and upon this 

 sill the outlet rested for a long period. 

 The lake surface then no longer oscillated 

 in response to varying climate but held 

 a constant level, and it was the long 

 maintenance of this level which enabled 

 the waves to carve and construct the 

 Provo shore line. 



The draining of the lake down to the 

 Provo level reduced its area by one-third 

 and correspondingly reduced the quan- 

 tity of water annually evaporated. Two- 

 thirds of the inflowing water was then 

 disposed of by evaporation and the re- 

 mainder was discharged through the out- 

 let. Only a great change of climate could 

 restore the balance between inflow and 

 evaporation, and the change was slow iiu 

 completion. . At last, however, the pen- 

 dulum of temperature swung far enough 

 on the side of warmth. The outlet chan- 

 nel ran dry, the lake basin was again 

 separated from the drainage system of the 

 Pacific, and -the lake began to shrink. 

 So long as there was outflow the water 

 was fresh, but when the outflow ceased 

 there began that accumulation of salt 

 which has made the water of the present 

 lake a concentrated brine. 



At times in the historj^ of the lake, 

 especially while the Provo shore line was 

 being formed, the tributary streams 

 brought down sand and gravel, which 

 they dropped at their mouths, building 

 deltas. When the water fell these de- 

 posits remained aa fan-shaped benches 



fronts 



treams 



built them then dug chan..^.^ .-.^.l^^xx 

 them. Part of the city of Ogden stands 

 on a delta bench built by O^den River 



Between Weber Canyon and Ogden the 

 railroad follows the channel that was 

 opened by Weber River through its 

 former delta. 



The climatic revolutions which created 

 and destroyed Lake Bonneville wrought 

 similar changes in all parts of the Great 

 Basin. In Western Nevada the traveler 

 sees the shore lines of another ancient 

 lake, known to geologists as Lake Lahon- 

 tan. It did not rise high enough to 

 establish an outlet, but its water was so 

 nearly pure as to be inhabited by fresh- 

 water shells. Some of its shores are 

 marked by heavy deposits of travertine. 

 "^Tien it died away there remained in its 

 basin a group of smaller lakes, some salt 

 and some fresh, but only one — Ilimiboldt, 

 a fre?h lake — can be seen from the train. 



The view from Ogden station is ob- 

 structed by biuldings and trees, but by 

 climbing to a near-by viaduct one may 

 see the bold face of the "Wasatch Range, 

 across which the line of the Bonne^dlle 

 shore is dra-wTi as a narrow pale band. 

 On the shore bench grow the ash-grecn 

 sage and other light-colored bushes, and 

 the steeper slopes are mottled by dark- 

 green thickets of dwarf oak. The west- 

 bound traveler obtains a better view by 



backward just after leaving 



looking 



recognize 



traces 



Provo shore line as well as the Bonne- 

 \'ille. Thes€ 



on Promontory Range and Fremont 

 Island; and if the air is clear the traveler 

 will have the old shore lines in view until 

 he leaves the Bonneville Basin near 

 Montello, 130 miles from Ogden. 



On the route from Ogden to the Yellow- 

 stone National Park the old shore lines 

 are prominently and almost continuously 

 in sight until the train enters Bear River 

 Canyon and may also be seen on a distant 



to the left. They reappear in 



range 



Cache Valley, beyond this canyon, and 

 are especially conspicuous at the left 

 where their terraces surround a range of 

 hills. At the Provo stage of the lake 

 these hills projected above the water as 



