tOO GEOLOGICAL EXCURSION TO THE ROCKY MOUNTAINS. 



ail of marine formation, and capped l>y the massive sandstones and 

 shales ofthe coal-bearing Laramie, The monoclinal valley followed by 

 the road shows well the peculiar topography which everywhere char- 

 acterizes wide exposures of these .Middle Cretaceous shales. 



At Lower Crossing may be observed an interesting example of Incon- 

 sequent drainage; where the Price river leaves the wide, open valley 

 in the soft clays and boldly cuts its way in a deep gorge through the 

 Book ('litis, in an easterly direction, to the Green river, which it reaches 

 L(> miles (LMJ km.) above the railroad crossing. 



The road now rises slightly before descending into the. valley of Green 

 river, and from favorable points one can see. far to the south, remark- 

 able castellated forms of erosion in harder beds of the lower portion 

 of the Mesozoic, broaghl ap by the monoclinal uplift of the San Rafael 

 swell (Plate Vin). In clear weather a glimpse may also be had. on the 

 distant Southern horizon, ofthe sharp laccolitic peaks of the Henry 

 mountains. 



Back of Green River station is a mound of dark shales, probably 

 belonging to the horizon known as Fori Benton Cretaceous, which 

 abounds in lish remains and inocerami. 



Green river, which is crossed at a point where but little can be seen 

 of its characteristic canyon scenery, is the main tributary of the Col 

 orado river of the West It takes its rise nearly 300 miles (483 km.) 

 due north ofthe crossing, in the Wind River mountains, and flowing 

 south across the interior Tertiary basin of Wyoming, famous for its 

 vertebrate remains, it cuts through the heart of the, linta mountains 

 in a series of deep, winding gorges carved out of the very hardest 

 siliceous rocks. It then Hows south through the Colorado basin, and 

 about GO miles (97 km.) below the crossing is joined by the Grand 

 river, which drains the western slopes of the Rocky mountains. It is 

 only after the confluence ofthe latter stream that it is called the Colorado 

 river. 



In the vicinity of Creen river, and especially on the east side, the 

 characteristic scenery of the Cretaceous shales is most marked, the 

 country being- absolutely bare of vegetation of any kind for long dis- 

 tances. The stations in this region are appropriately named Desert, 

 Sphinx, Solitude, etc. The accompanying sketch (Fig. 21) of the latter 

 was made from the train by Mr. Cadell. 



The Valley of Desolation in these shales is followed forSO miles (80 km.) 

 east of Green river. The road gradually rises over low divides, being 

 at times more than a thousand feet (305 m.) above Creen ri\er, and then 

 descends into the valley of Grand River. In clear weather tine views 

 are had, from elevated points, of the laccolitic group of peaks lying 30 

 miles (48 km.) to the south and east, known as the Sierra la Sal, n 

 whose summitshave elevations of 12,000 to 13,000 feet (3,668 to 3,962 m.). 



At Cisco an artesian well has a considerable ilow of water, the surplus 



