PEALE.] DESCEIPTIVE GEOLOGY BEAR LAKE PLATEAU. 583 



beds. Immediately south of tlie lake the older beds outcrop where the 

 Wahsatch beds are removed, as I shall describe a little farther on. In 

 1871 Dr. Hayden crossed the plateau very nearly on our south line. He 



says :* 



After crossing Spring Creek, near Laketown, yre enter a deep canon with massive 

 strata of limestone, inclining about northeast 50° to 70°. We have at the bottom lirst, 

 very irregular-bedded, massive, cherty limestone, with no fossiL?; secondly, a yellow, 

 calcareous sandstone of varied texture; thirdly, limestone in thin strata, very much 

 warped or bent. * * * From the summit to Bear Eiver Valley the variegated beds of 

 the Wahsatch Group conceal all the older rocks. 



From the divide we descended the valley of Sage Creek to Bear Eiver Valley. The 

 Tertiary strata are nearly horizontal on either side. These rather modern beds par- 

 took of some of the later movements, and inchne at angles from 1° to 10°. 



Station 107 was located in the east side of the plateau about seven 

 miles north of our south line. Gray congiomeritic sandstones outcrop 

 on the station, and below them red and purphsh sandstones, and below 

 the latter light-greenish and white sands and marls. All these beds 

 dip gently to the eastward from the station, seeming to jjass beneath 

 the alluvial deposits of Bear Eiver Valley. West of the station the dip is 

 to the west, but the beds soon become horizontal, rising again a little as 

 we approach the western edge of the i)lateau near Station 108. North 

 of Station 107 the westward dip in these beds becomes greater, and the 

 eastern side of the fold has been considerably eroded, so that we find 

 that instead of a plateau there is a ridge of hills, which have been 

 named the Boundary Hills, from the fact that the western boundary line 

 of Wyoming crosses them, following approximately their strike. Kear 

 the edge of Bear Eiver Yalley the Wahsatch beds show in the hills as 

 far north as opposite the mouth of Smith's Fork. On the summit they 

 extend much farther north, forming the capping of the ridge. 



Station 108 is on the w^est side of the plateau, about six miles north 

 of Station 107, and about eight miles farther west ; Station 108 is on 

 basalt, which has the appearance of being derived from a dike. There 

 is no other remnant of basalt anywhere else on the plateau, nor, as far 

 as seen, in the surrounding country south of Soda Springs, and this 

 basalt is evidently not derived from the same soiu'ce as that of Black- 

 foot Basin. It forms the capping to the station, which is a prominent 

 hill, as seen from the surrounding country. On the maps published by 

 the General Land Office it is named Mount Kimball, and this name has 

 been adopted by us, as our plan has always been to use accepted names 

 tor mountains and peaks wherever we can find they have been named 

 either by the settlers or previous explorers and surveyors. 



Below the station the following section was made : 



Section No. 26. 



1. Basalt. 



2. Coarse Avhite sandstones. 



3. Soft red sandstones with congiomeritic bands. 



The entire thickness, including the basalt, is about 1,000 feet ; 800 

 feet is probably the thickness of the Wahsatch beds here. They are all 

 below the beds of Station 107. I was unable to get a section that gave 

 me the entire thickness of the Wahsatch beds on the plateau. Below 

 the beds of the section just given a coarse limestone outcrops, one layer 

 of which is filled with remains of an indistinct ostrecij like Ostrea strigu- 

 lecula. The dip of these limestones is eastward, and the outcrop is 

 on the east side of a gully, which separates the Wahsatch beds from a 



*Eeport U. S. Geolog. Survey for 1871-72, pp. 157-158. 



