esdlich.] WIND EIVER RANGE — GLACIEES. 91 



are filled with water. Eliminating the minor curves made by the moving 

 ice, the length of this glacier must have been 16 to 18 miles. This is one 

 of the largest, but in its effects may be regarded as a type for other 

 occurrences in the same region. An interesting feature was often observed 

 relative to the melting or gradual receding motion of glacial masses. 

 Eor some distance entirely bare rocks frequently composed one-half or 

 two-thirds of the surface over which we travelled. They were smoothed, 

 grooved, and striated. Besting upon them were innumerable pebbles 

 and bowlders, ranging in size from that of a goose-egg to several feet in 

 thickness. Standing thus upon the smooth, inclined surface of a rock 

 in positu, these erratic blocks looked as if they might have been left there 

 only a year ago. !N"o signs of weathering action were visible in either, 

 and often the blocks were so delicately poised that it would seem as if 

 a breeze could disturb their position. Entire "fields" of this character 

 were found, showing the direction toward which the glaciers shrunk. 



On the eastern slope of the range numerous glacial moraines were 

 noticed ; they are generally smaller than on the other side, a fact which 

 is partly owing to the orographic configuration there existing. Beyond 

 the metamorphic area the evidences of glaciers extend for a short dis- 

 tance only. In spite of the enormous masses of moving ice and accom- 

 panying bowlders, we find in the Wind Biver Mountains a confirmation 

 of the rule that glaciers produce no radical changes in the character of 

 any given region. By the abrading action of both ice and accumulations 

 of bowlders and sand, projecting rock-ledges and points reaching out 

 toward the glaciers have been removed. Excavations within valleys 

 already existing have been made. Material has been taken from one or 

 more points and has been deposited at others. In other words, the detail 

 features exhibited by the localities through which or over which the ice 

 has passed have been modified. This limits the extent of changes 

 wrought by glaciers. 



When first I saw the eiiormous accumulations of snow and stationary 

 ice in the main chain of the range (at the end of July), I fully expected 

 to find active glaciers within its deeper canons. In this I was disap- 

 pointed. The extremely " fresh " appearance, however, that many of the 

 occurrences above described exhibit has induced me to believe that 

 glaciers existed in the Wind Biver Mountains until within a very recent 

 period. Indeed, I should not be surprised to hear at any time of the 

 discovery of moving ice-fields of small extent within the deep caiions of 

 this range.* 



LAKE DEPOSITS. 



Within the region east of the Wind Biver Mountains we found a num- 

 ber of alkaline lakes of small extent, and beds of others that were dry. 

 Although these, in a certain sense of the word, can be termed " lake 

 beds," they are not to be considered here. On Beaver Creek, about 6 

 miles below its sharp turn to the northward, we found an extensive lake 

 deposit. Fine arenaceous clay, silt, and sand have here been deposited in a 

 large, level valley. Conformable to the color of the original material 

 from which this drift was derived, we observe alternating bands of red, 

 gray, yellow, and brown deposits. Varying with the color necessarily 

 we find the different layers showing some changes in their composition. 

 We had no means at hand to determine the thickness of this accumula- 



*Note. — During the past summer (1878) active glaciers of small extent have heen 

 discovered in the Wind Kiver and Teton Ranges. The large masses of snow during 

 the summer of 1877 covered them entirely, so that we passed over them without recog- 

 nizing their existence. In the Annual Report for 1878 full descriptions of these glaciers 

 will be given. — E. 



