0. a Marsh— Geohgy of the Uintah Mountains. 195 



tion. From the base of the Uintahs, as far south as the eye 

 could reach, the soft beds of the more recent formations had 

 been washed away to a depth of one or two thousand feet, leav- 

 ing at the bottom of the great depression the liare, upturned 

 edges of the variegated Mesozoic strata on wliich th(>v luul 

 rested. The flanks of the adjacent mountains uvn- -ashed by 

 deep canons leading into the basin, showing rhe <o\\we horn. 

 which the denuding agent came. Our course hiy through this 



.-in, and descending with great difficulty by an obsmiv Indian 

 . we passed on, through dry canons and over steep iut< r\ rn- 

 ridges to Brush Creek, a small stream which ii..\\ hdps tc 



>i ni tiiis region into the Green Eiver. The rim ot tlii< givnt 

 -•u.-iu where we descended was composed of nearlv Imnzonhii 

 heds of conglomerate, underlaid by light colored elavs and .sn: . 



of red and yellow sandstones and shales, whirli dip to tlio -■ : 

 away from the mountains, but in places have been nine!: eui-\ > . i 

 and folded. The upper, horizontal beds. ai>iKUvntly Tei-tiary 

 deposits, were evidently identical with tliose ob<erv«'d on the 

 Green Eiver at "Brown's Hole;" and that valley, as well as this 

 lower basm, owes its present size, if not its origin, to the readi- 

 ness with which these strata are eroded. 



Near Brush Creek, and about six miles from Green River, a 

 seam of bituminous coal was discovered in the side of a drv 

 which cuts through a high ridge of sandstones and 

 This seam was about a foot in thickness, and mdic- 



hlfi 



tions of others were seen at various points m 



the basin. The 



strata containing the coal where first seen dip about 60 to the 

 north, and form part of a denuded anticlinal. The weathering 

 of the thickly bedded sandstone above the coal had developed 

 liuge concretionary masses, some of them fifteen feet m diam- 

 eter, which projected from the clifi", or had fallen into the ravine 

 below. As the age of the coal deposits of the Rocky Mountain 

 region has of late been much discussed, a careful examination 

 was made of the series of strata containing the present bed. ana 

 their Cretaceous age established beyond a doubt. In a stratum 

 of yellow calcareous shale which overlies the coal series con- 

 formably, a thin layer was found full of Ostrea congesta Conrad, 

 a typical Cretaceous fossil ; and just above, a new and yerv in- 

 teresting crinoid, allied apparently to the Marsupites of the i^.ng- 

 Hsh Chalk. In the shales directly below the coal bed, eycloidal 

 tish scales and coprolites were abundant: and lower do\\n. re- 

 mams of Turtles of Cretaceous types, and teeth of a A^'n*'saui i.in 

 reptile, resembling those of Megalosaurns, were also diseo\eiei . 

 After passing out of the deeper y-^- -^ *^^- '--'" '^" <^'^^ 

 way southward, and proceeding aboi 

 stream, which on the Government maps i 



