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GUIDEBOOK OF THE WESTERN UNITED STATES 



which now appear as prominent shelves. Near Tipton (see sheet 

 12, p. 70) the train crosses one of the harder layers of the Wasatch 

 beds, a shelf-making sandstone, which may be seen to the left, 

 south of the raiboad, rising higher and higher toward the west until, 



on Table Rock 

 is about 800 fe 



XIV 



the track. These rocks near 



Tipton contain great numbers of shells of fresh-water mollusks and 



some 



may be obtained 



view of Table Rock, a prominent point m the eastward-sloping shelf 



just mentioned. The low hills south of the station 

 Bitter Creek. ^^^ covered with gravel deposited by Bitter Creek 



before that stream had eroded to its present depth. 



TVia rrrnvpl« pnn+.nin mnnv flfrnte nebbles. some of 



Elevation 6,692 feet. 

 Omaha 704 miles. 



fully 



A well drilled at this station years ago to 



found water under sufficient 



the surface, but too alkaline to be of much use. 



West of Bitter Creek station the railroad crosses the eroded edges 

 of eastward-dipping strata that range in age from middle Eocene to 

 Cretaceous. At Patrick siding these strata have the same general 



"Wasatcl 



ui 



These ridges are parts of the east limb of the Eock Springs dome.* 



Tlie Cretaceous rocks that are covered Almond coal group, 900 feet tliick, said 



by tlie Tertiary beds of the Great Divide 

 Basin on the east and those of the Bridget 

 Basin on the west are exposed between 

 Black Buttes and Rock Springs because 

 they have been arched up into a great 

 dome from the top of which the younger 

 beds have been removed by erosion. The 

 major axis of this dome is about 90 miles 

 long and trenda nearly north and south 

 close to the west limb of the dome. The 

 beds on the west dip 15° to 30*^; those on 

 the east dip 5*^ to 10°. The minor axis is 



to be of upper Mesaverde age; (5) the 

 Lewis shale, 750 ± feet thick; (6) the 

 Black Buttes coal group; and (7) the 

 Black Rock coal group, of Tertiary age. 

 It has been estimated that the amount 

 of coal in the Rock Springs field available 

 for mining^that is, within 3,000 feet of 

 the surface and in beds 2\ feet or more in 

 thickness— exceeds 142,000.000,000 tons. 

 As coal is fossilized vegetal matter, the 

 traveler, as he views the barren hillsides 

 where now scarcely a living thing can be 

 about 40 miles long and passes through seen, may well wonder how all this great 



I 



the dome south of Rock Springs. The store of carbonaceous matter came there, 

 oldest rocks exposed are the shales near 'Those coal beds are mute but forceful 



I 



Baxter siding, which correspond to the reminders that desert conditions have not 

 Steele shale seen farther east. Around always prevailed in this region. Fossil 

 this shaly center' outcrop in concentric ' plants, such as palms, figs, and magnolias, 



zones (1) a series of non coal-bearing sand- found at many places in these coal beds 

 stones; (2) the Rock Springs coal group, I prove that the carbonaceous matter of the 



600 to 2,400 feet thick, of lower ilesaverde 

 &^; (3) a massive sandstone, 800 feet 



coal accumulated in swamps at a time 

 when the climate was as mild as that of 



thick; of middle ilesaverde age; (4) the Florida at present. 



