602 EEPOET UNITED STATES GEOLOGICAL SUEVEY. 



tained, looking north from Station a, it appears that the valley must 

 have had some of the lake deposits removed prior to the pouring out of 

 the basalt. The latter is at a lower level than the conglomerate at Sta- 

 tion b. The amount of erosion since the flow is measured by the depth 

 of the canon in the basalt at the north end of the valley ; this is 250 to 

 300 feet. 



I did not visit the mountains on the west and east sides of the valley, 

 so cannot give any definite information as to the relation of the lake- 

 beds with the older beds of the ranges. 



The conglomerate of Station b is probably of the same age as *the con- 

 glomerate in the synclinal depression east of Station 7G. There is but 

 little doubt that the lakes filling these valleys were connected. The 

 Pliocene lake probably had the greatest extent, and included what were 

 afterwards divided into several distinct bodies of water. 



MIDDLE CANON OF BEAR EIVEB. 



I have applied this name to the caiion through which the Bear flows 

 on its way from Gentile Valley to Cache Valley. It is about 12 miles in 

 length, and the walls are from 1,000 to 1,500 feet in height. A station 

 was made on the west side, at the head of the caiion, about 800 feet 

 above the level of the river, on dark-blue laminated ..limestones, which 

 dip about north 17° east at an angle of 40° or 50°. Where the beds cross 

 to the east side the strike seems to curve around to the southward, so 

 that the dip is more to the eastward. On the hills west of Mink Creek, 

 about four miles south of the head of the caiion, brownish quartzites out- 

 crop with a strike south 67° east, dipping north. 23° east, at an angle of 

 50°. Wear the south end of the caiion the beds dip more to the south, with 

 an angle of 65° noted in limestones. The quartzites lie between the 

 limestones at the head of the caiion and those at the foot. We had two 

 sub-stations (a and b) on the east side of the caiion. The hill on which 

 station a was located was covered with quartzitic pebbles, and it is 

 probable that quartzites underlie the station. Station b was on a dark 

 limestone which dip 50° approximately to the south, as already noted. 

 Between the two stations the following beds were noted : 



Yellow sands and marls. 



White limestones and shales. 



Pea-green shales and sands. 



There is probably 600 or 700 feet of these beds which I consider to be 

 of Pliocene Tertiary age, as they are so much like the beds containing 

 Limnwa, Planorbis, &c, at other localities. They dip north 23° east at 

 at an angle of 65°. . They are, therefore, unconformable to the lime- 

 stones. The outcrop crosses to the west side of the caiion. That re- 

 gion was not fully investigated, but there is very little doubt that the 

 beds about the head of Cottonwood Creek are the continuation of the 

 beds just described. The whole region was too cursorily examined to 

 say much about it. Where the Bear leaves the caiion and bends west- 

 ward to enter Cache Valley the greenish Tertiary beds outcrop on the 

 southeast side, dipping 10° towards the south. They rise again a short 

 distance beyond. 



On the east side of Mink Creek, at Station 118, Gannett obtained a 

 few fragmentary fossils which have a Silurian facies. The strata from 

 which they were obtained have a westerly dip. Mink Creek has a 

 course almost parallel to that of the Bear while it is in the canon, and 

 joins it as soon as it leaves the caiion to turn westward. Near the head 

 of the creek an outcrop of shales was seen which appeared to rest un- 



