230 VALLEY OF GREEN KIYER. 



a pretty little stream of good water, which also takes its rise in the 

 Bear-river Mountains, near the heads of Black's Fork, into which 

 it falls about twelve miles below Fort Bridger. Continuing in the 

 valley of Black's Fork, after a march of nearly eighteen miles en- 

 camped on its right bank, about half a mile above the mouth of the 

 Muddy, another affluent coming in from the left. Lat. 41° 28' 

 56'^38; long. 110° 18' 50''. 



Since leaving the basin and entering the valley of Green River, 

 a remarkable change in the face of the country is apparent. In- 

 stead of the distm'bed and upheaved rocks which characterize that 

 region, flat tables or terraces of horizontal strata of green and 

 blue sand and clay, and sandy conglomerate, or agglutinated sand, 

 now form the principal feature of the country, standing alone, like 

 island buttes, amid the barren plains, or forming escarpments 

 which alternately impinge upon the banks of the winding streams. 

 These tables, which extend from the rim of the basin to the South 

 Pass, and thence to Brown's Hole on Green Biver, are apparently 

 the result of a deposite in still water. The layers are of various 

 thicknesses, from one foot to that of a knife-blade, and the hills are 

 fast wearing away under the influence of the wind and rain. 



The whole country looks as if it had, at one time, been the bot- 

 tom of a vast lake, which, bursting its barrier at Brown's Hole, had 

 been suddenly drained of a portion of its waters, leaving well- 

 defined marks of the extent of the recession upon the sides of these 

 isolated buttes. As the channels became worn by the passage of 

 the water through the outlet into Green River, another sudden de- 

 pression followed, and the same operation was repeated at still a 

 lower level. There are three well-defined levels, and the same ap- 

 pearances of horizontal water-lines occur here as were noticed upon 

 the hillsides of the islands in the Great Salt Lake.; save that in the 

 latter case they are more numerous and closer together, and the 

 subsidence of the waters appears to have been more gradual. The 

 surface of the ground was strewn with fragments of obsidian, black, 

 shiny pebbles, flints, and white, yellow, and smoky quartz. 



A high wind from the W. S. W. blew up clouds of dust, 

 and, at every turn of the road, announced the approach of crowds 

 of emigrant- wagons, wending their way to the Mormon valley, with 

 droves of cattle and sheep, whose fat and thriving condition, after 

 so long a journey, was the subject of general remark, and excited 

 universal admiration. 



Thursday, September 12.^Last night was very cold, and at sun- 



