peale.] DESCRIPTIVE GEOLOGY BEAR RIVER AREA. 603 



conformably on the limestones with a dip towards the west. The beds 

 were obscure, and I am not certain as to their position and relations ; 

 they may represent a portion of the Pliocene. 



At Station 11(3, massive limestones outcrop with dips to east or south- 

 east. This region is exceedingly complicated and will require consider- 

 able close examination to determine the relations. The cafion of the 

 Bear was probably in part eroded subsequent to the upheaval of the 

 beds that I have referred to the Pliocene. When the orographic disturb- 

 ance at the end of the Tertiary took place the basin of Gentile Valley 

 was separated from that of Cache Valley. Whether the erosion of the 

 canon began then or after the draining of the lakes, I cannot at present 

 say. The caiion is almost at right angles to the strike of the beds and 

 must have been determined by a pre-existing fissure or a fissure made 

 at the time of the uplift. 



CACHE VALLEY. 



The portion of Cache Valley that lies within our district is about 3G 

 miles in length and from 7 to 12 or 15 miles in width. It is well settled 

 by a prosperous farming population, and the land appears, to be in a high 

 state of cultivation, especially in the southern portion. The entire pop- 

 ulation is 8,229 by the census of 1870. The towns in our district are 

 Franklin, Eichmond, Smithfield, Hyde Park, Newton, Clark, Clifton, 

 Weston, and Oxford. The town of Logan, which is the county capital, 

 is only a short distance south of our line. The towns are generally on a 

 streams coming from the mountains, and the water is used for irrigating 

 the fields which surround them. 



Geologically Cache Valley begins as a broad synclinal below our line, 

 but north .it probably overlies or occupies the place of several folds. 

 The Adew of the valley from the surrounding hills is one of exceeding 

 beauty, especially in August, when the fields are golden with the ripen- 

 ing grain. The groves of trees, which mark the towns, with their white 

 and red buildings, stand out in strong relief. The whole valley can be 

 seen at once, and the terraces on its sides and the basin-like character 

 of the depression, point to its former character of a lake-basin. This is 

 confirmee! when we come to examine its deposits. As Dr. Hayden said 

 in 1871, " Cache Valley opens into Salt Lake Valley," " and one cannot 

 doubt that the lake itself formerly extended all over Cache Valley." An 

 examination of the beds occupying the valley shows at least two groups 

 of lake deposits : First, those that have been referred to the Pliocene, 

 named by Dr. Hayden the Salt Lake Group ; second, the deposits in 

 the central portions of the valley. These I have named the Cache 

 Valley Group. The former, as we shall see, are generally disturbed, 

 and the latter are horizontal in position. The latter, on closer study, 

 may have to be divided into several groups to correspond with the 

 various lakes from which they were deposited. By this I mean that the 

 terraces show a number of lake levels, and on the lowering of the lakes 

 the areas became more restricted ; so in the terraces we find groups of 

 strata older as we go up, while in the centre of the valley the succes- 

 sion will be continuous. The drift has covered these beds to such an 

 extent that the divisions cannot always be recognized, so that I have 

 included them under one head. Until a series of level-lines are run, 

 they cannot be outlined on the map. 



I shall now present the facts obtained in relation to the different 

 parts of the valley, beginning with Logan Fork, which is almost on our 

 south line. 



