72 



GUIDEBOOK OF THE WESTEEX ITXITED STATES. 



Tlie gorge extends to tlie mouth of Bitter Creek/ where the train sud- 



denly emerges from its nurrow confines directly into the broad valley 

 occupied by Green River„ 



the sTirface "vras a thousand feot or more 

 higher than it is now — that is, higher than 



•^ In order to understand why Bitter its channel as fast as the dome rose, or it 

 Creek established itself in itp present i "woiild have been deflected, 

 ooursej vre must consider conditions that I A similar explanation accounts for the 

 existed here millions of years ago. This ; behavior of this stream west of Ptock 

 stream cuts its "way directly across the Springs. Its course was established when 

 Rock Springs dome instead of flowiug 

 around it and theUj seemingly regardless 

 of what would be easy lines of erosion, ! the i>resent top of Table Mountain. As 

 flows across the broad valley west of Rock the master stream, Green River, cut its 

 Springs and plunges through AVliite iloun- j course lower and lower, the smaller 

 tain, in which it has cut a gorge 1,000 feet ^ stream, Bitter Creek, cut the narrow 

 or more in depth. This apparently un- gorge through Table Mountain. But far- 

 ther east, where the same sedimentary 

 rocks that compose this mountain were 

 more steeply upturned and more easily 



reasonable course was established long 

 ages ago, Avlien this part of the country 

 was lower than it is now and the distant 



mountains, then newly formed and rug- 

 ged, supplied the streams wdth more sedi- 

 nient than they could carry. This ma- 

 terial was deposited on the lower lands, 

 building them up just as flood plains and 

 deltas are being built up in some places 

 at the present time. The resulting accu- 

 mtdations of sediment constitute the 

 Wasatch, Green River, Bridger, and other 

 formations of Tertiary age. 



There came a time, however, when the 

 region thus built up was uplifted so much 

 as not only to stop deposition but per- 

 haps also to divert the streams to new 

 courses and cause them to cut downward 

 into the beds of sediment wTiich they had 

 previously deposited. The surface was 

 not raised the same amount in all places 

 and the uplift was accompanied by 



warping and fracture 



East 



of Rock Springs the upheaval produced 

 a great dome. In other fractxired places 

 the rocks slipped past each other and pro- 

 duced faults. These mo\''ementa :crere 

 verv^ slow, and for this reason Bitter Creek 



while the g 



rose 



Doul>tiess 



xni 



but the} are so slow ihat the lifetime of a 

 man is not long enough to enable him to 

 detect a change. The oldest inhabitant 

 of Bitter Creek valley would probably 

 insist that the creek had not deepened 

 its channel during his lifetime, vet it cut 



eroded, Bitter Creek and its tributaries 

 cut down a vast area to a level much 

 lower than the top of Table Mountain, 



The volume of rock removed by this 

 small stream alone would probably be 

 reckoned in hundreds of cubic miles, and 

 all of it found its way through the narrow 

 gorge to Green River. Hundreds of other 

 streams delivered similar amounts to the 

 ! riA'er, and the question may well he 

 asked, VvTiat became of it all? Those who 

 have vis:ited the Grand Canyon of the Colo- 

 rado in Arizona have noted the muddy 

 waters of that river" and wondered where 

 the mud came from. Some of it came 



omin 



ha\ 



the built-up plains and filled basins that 

 mark the ancient course of Colorado River 

 in western Arizona have wondered where 

 the material came from to fill these 

 enormous basins. Some of it came from 

 the valleys through which the Union 

 Pacific Railroad is built. Those who 

 have traveled over the Southern Pacific 

 line in southern CaUf ornia , where it 

 crosses the broad delta which the Colo- 

 rado built out across the Gulf of California 

 so far that the north end of the gulf — now 

 the Salton Sink — was completely cut off 

 from the main pai't of the gulf, have won- 

 dered where all the sand and silt of that 

 great delta came from. Some of it once 

 rested on the arch of the Rock Springs 

 dome. 



