48 SEDIMENTARY GROUPS OF THE PLATEAU PROVINCE. 



ceous, ferruginous shales, with occasional beds of* soft sandstone, all weath- 

 ering easily; and the line of junction between that and the massive gray 

 sandstone which forms the summit of the Point of Rocks Group can be 

 plainly seen. In these shales immediately overlying the massive sandstone 

 there are beds and seams of coal. The first massive sandstone is the Upper 

 Hogback Sandstone. These rocks all have an easterly dip, and as you go 

 westward you soon reach the base of the Upper Hogback Sandstone, then 

 pass the beds of irregularly bedded shales and sandstones until you reach a 

 second massive, gray sandstone, which in many places is broken into two 

 or more beds. This is the Middle Hogback Sandstone. Still going west- 

 ward, massive and thinly bedded sandstones of yellowish-buff color alter- 

 nating with massive beds of light gray or white sandstone, are seen. About 

 six miles from the station -the railroad turns southward and debouches 

 from the narrow canon valley of* the Point of Eocks into the broad open 

 valley of the Salt Wells. To reach the base of the Point of Rocks Group 

 it is necessary to diverge from the railroad, which passes along the foot of 

 the cliffs, and eontinue in a westerly direction until the last massive gray 

 sandstone is reached. It will then be noticed that the massive beds, both 

 yellow and gray, have been passed, and that another series of more thinly 

 laminated beds underlie the massive series. These alternating beds of gray 

 and buff belong to the Golden Wall Group. The separation between these 

 two groups at this point is not as plainly marked as at many other regions. 

 The whole thickness at this locality is about 1,800 feet. 



When Messrs. Meek and Bannister made their section along this line, 

 or their Point of Rocks Section, they commenced a few hundred feet below 

 the summit of the group and ended about 300 feet above its base, which 

 was not seen by them; for in turning southward with the railroad they 

 crossed two great faults having their throw to the north. The lines of fault- 

 ing pass along a valley showing no rock exposures, and when they passed 

 out into Salt Wells Valley they were on beds of the Salt Wells Group at a 

 horizon of six or eight hundred feet below the summit. 



Another good section of this group can be obtained at Rock Springs. 

 A few hundred yards west of the mineral spring known as Rock Spring, a 

 great, massive sandstone stands in a ledge, the beds dipping to the west at 



