172 REPORT UNITED STATES GEOLOGICAL SURVEY. 



On the south side of the river the upper layers appear to have been 

 eroded away, not showing until the mesas, five or six miles south of 

 the river, are reached. 



The caiion of the Grand appears to be impassable, and the road makes 

 a detour around it. It is thirty miles from where the road leaves the 

 river, above Station 5, to the point where it touches it again, below Sta- 

 tion 8. The gullies crossed in this distance are all dry, with the excep- 

 tion of Salt Creek, the water of which is alkaline. Although dry, these 

 gullies are deep, especially between Stations 7 and 8. 



The following is the section at Station 8 : 



Top. 



1. Massive yellowish sandstones with faint impressions of 1 



stems > 250 feet. 



2. White marls and reddish sandstones ) 



3. Dark-colored hard sandstones, with a layer at the base ) 

 containing nodules of jasper. , ( 



4. Variegated marls } 260 feet. 



5. Greenish marls and sandstones with thin bands of lime- | 

 stone at the base - \ 



6. Massive red sandstones (top of Trias ?) 



Total , 510 feet. 



It is difiScult here, as at the other localities, to draw the line between 

 the base of the Dakota group and the top of the Jurassic. 



Between Station 7 and Station 8 is a kind of basin of Jurassic 

 shales, the stations being located on two points or tongues of the Da- 

 kota sandstone. North of the hogback ridge of Dakota sandstone the 

 shales form low bluffs, and between these and the foot of the Book 

 Cliffs the surface is diversified by buttes and mesas eroded from the 

 shales. The Dakota sandstones dip toward the northwest 30-5<^. 



Bitter Water Creek joins the Grand below Station 8; and just below 

 the mouth of the creek, the river enters a canon in the Red Beds. This 

 canon is 500 or 600 feet in depth at its head, and this probably increases 

 as the river is followed. 



From the head of the canon to the Horse-shoe Bend, the Eed Beds 

 outcrop on both sides of the river. Station 9 was located on a Jurassic- 

 capped butte on the north, or rather west side of the river, for the Grand 

 here is flowing but a few degrees west of south. On the east side its 

 tributaries cut profound caQons in the Red Beds, and at their sources 

 may even expose the underlying granitic rocks. 



At Horse-shoe Bend the valley becomes more open, and below the 

 bend the river flows from the Red Beds into the Jurassic shales. Below 

 the mouth of Granite Creek the Grand makes a right-angled bend and 

 flows to the southwest, cutting across the hogback ridge into a syncli- 

 nal basin of Cretaceous shales. The strike of the Dakota group is at 

 right angles to the course of the river, and just above the mouth of the 

 Eio Dolores we find the Grand again cutting across the Dakota group 

 at right angles to its strike. The synclinal depression between the 

 Dolores, Granite Creek, and Grand River is the result of two folds 

 meeting, viz : that of the northern end of the Uncompahgre Plateau, and 

 the fold that marks the western edge of the same plateau farther south. 

 This latter fold, with its axis slightly changed (*. e., more to the west- 

 ward), continues from the Grand to Green River. A line of hogbacks, 

 capped with the Dakota sandstones, is seen stretching to the westward 



