620 JOHN LYON RICH 



sand spread out from the mountains far over the plains, while at 

 the same time smaller fans spread out in like manner from the 

 monadnocks of the plains and merged with the gravels from the 

 mountains. 



It seems likely that this mountain uplift was accompanied by 

 tilting of the land for twenty miles or so north of the mountains, 

 for, as stated already, the rock-surface over this area slopes toward 

 the north at the rate of about seventy-five feet per mile; a slope 

 which seems too great to have remained undissected under the 

 conditions of planation. 



The Uintas at the time of the deposition of the gravels rose to 

 a much greater height than at present, for to the south of Little 

 Mountain and Miller Mountain the present summits of the range 

 are little if any higher than the base of the gravels on these plateaus. 

 The highest summit north of Green River is about 8,250 feet, 

 while the summit of the plateau at Miller Mountain is 8,500 feet 

 and Little Mountain is still higher. South of the river the moun- 

 tains are somewhat higher, but even here they are only fron 300 

 to 1,000 feet above the tops of the gravel-capped plateaus. This 

 in a distance of from fifteen to twenty-five miles gives a slope 

 entirely inadequate for the transportation of the coarse gravel 

 found on Miller Mountain. If the present grade of the gravel sur- 

 face on Miller Mountain, one hundred feet per mile, were pro- 

 longed for fifteen miles it would amount to a rise of 1,500 feet. 

 This is not enough, for the fans were necessarily steeper near the 

 mountains than farther out so that at the very least the mountains 

 must have been 2,000 feet higher than now to give sufi&cient grade 

 to account for the transportation of the gravels to their present 

 position, and this is not taking into account the still greater eleva- 

 tion necessary to furnish a supply ground for the material of the fan. 



The course of Green River during this time of mountain-building 

 cannot be discussed here, as its relation to the gravels close to the 

 base of the mountains is not known to the writer. At present it 

 flows between the gravel-deposits of Miller and Little mountains 

 and the higher parts of the Uintas from which the gravels were 

 derived. We are led then to one of two alternatives: either the 

 river was not flowing in its present course at the time the gravels 



