158 GEOLOGICAL SUEVEY OF THE TERKITOEIES. 



general terms that tlie metamorphic quartzites crop out occasionally, 

 though seldom, but high ridges of Carboniferous limestones, with the 

 strata inclining at all angles, are frequently uncovered over large areas. 

 From Soda Springs to the south end of the lake, and even much farther 

 southward, the high ranges of hills on the east side are composed 

 of a nucleus of limestones uncovered here and there. Sometimes a 

 vast thickness of the variegated quartzites conform to and conceal the 

 liDiestones, while in the intervals between these great anticlinal ridges, 

 and sometimes covering them, is a vast thickness of the more modern 

 deposits of the Wahsatch group. Ascending the divide eastward from 

 Bear Lake Valley, I estimated the thickness of the older strata to be 

 6,000 feet, 4,000 of which are Carboniferous limestones and the remainder 

 quartzites and sandstones. 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 partook of some of the later movements, and 

 incline at angles from 1° to 10°. The valley where we entered it is about 

 three miles in width, and soon expands to five miles. About live miles 

 below the village of Eandolph, on the east side of Bear Eiver, there is 

 one of the ruggedest walls of Carboniferous limestone I have seen on the 

 trip. The rocks seem to rise up from the river-bottom almost verti- 

 cally; the summits are weathered into jagged points, and the sides 

 of the wall, from summit to base, are gashed with dry canons or gulches, 

 which form splendid cross-sections of the strata. The trend of the ridge 

 is about northeast and southwest ; the dip northwest 60° to 70^. The 

 limestone is usually pure, light-gray color, not as compact as usual, 

 full of fossils, mostly in a fragmentary condition. Still these fossils 

 show most clearly that the limestones are of Carboniferous age. This 

 range of m.ountains, as it might properly be called, forms a very singu- 

 lar exhibition of the dynamic forces that have produced the remark- 

 able folds in the older sedimentary rocks. It may be called an oblong 

 quaquaversal, or an isolated pulf or bulge in the crust. The entire 

 range is not over eight miles in length and not over two or three miles 

 wide. The limestones bend down from the summits like the steep, 

 flexible, convex roof of a house. About three miles above Eandolph, 

 at the bend of the river, the limestone ridge breaks off suddenly. On 

 the south end the strata seem to be inclined at a greater angle, in some 

 instances passing a vertical. A fragment has been cut off at the south 

 end, where a stream has at some i^eriod very remote in the past made its 

 way through. This section shows the strata clearly, and as well the way 

 they flex down around the end of the range. The bend of Bear Eiver is not 

 long, but quite abrupt. Far to the south the country is open, flat, and 

 appears like a river valley, surrounded by low hills. The character of 

 this limestone range would indicate depression of the surrounding 

 country as one of the causes of the convex form of the sides. At any 

 rate, within the space of about ten miles from east to west, there are 

 two of these remarkable limestone ridges, where 3,000 to 4,000 feet of 

 strata seem to be corrugated into quite remarkable folds, with synclinal 

 intervals that have been filled up with the modern Tertiary beds. 



I will not delay at this time to discuss the causes that may have led to 

 this wrinkling of the crust, but simply state my observations and wait 

 patiently for a greater array of facts. From the bend of Bear Eiver to 

 Evanston the strata are not much disturbed, usually not inclining more 

 than from 3° to 10°. In the caiion southeast of the bend I was in- 

 formed that coal had been found. From the end of the limestone ridge 

 to the railroad, in every direction, the rocks exposed are not older than 



