292 GEOLOGY. 



after terrace was formed, each representing a stage of quiet in the 

 upward movement of the land. There are some indications that 

 this upward movement continued until this section of the continent 

 stood considerably above its present level. This is known to have 

 been the case in Europe, where even local glaciers were formed at 

 this time, which disappeared only when a movement in the oppo- 

 site direction had once more brought the land to a lower level- 

 The following section indicates some movement of this kind for 

 extreme southwestern Nebraska. It was taken in a canyon leading 

 into the Republican Valley, immediately west of the west line of 

 the State in Colorado. I saw similar sections, however, on the 

 Nebraska side of the State line: 



1. Black soil 1 foot. 



2. Drift 2 feet. 



3. Alluvium 2 " 



4. Black soil 75 " 



5. Alluvium 4 " 



6. Lre-s 4 " 



7. Alluvium 4 " 



8. Black i oil 1 foot. 



9. Loess aud Drift 4 feet. 



10. Black soil 1.25 " 



This section tells its own story a history of frequent changes of 

 level. After the last Loess was laid down, river alluvium was de- 

 posited, on top of which appeared a black soil, which was again 

 flooded and covered with alluvium. On top of the last, Drift ma- 

 terial, which most nearly resembles glacial Drift, was formed, 

 which in turn gave way again to the present black soil of this re- 

 gion. It would not be surprising if further investigation should 

 confirm the explanation suggested above that the upward move- 

 ment of the Terrace Epoch continued until a much higher level 

 than the present was reached. Local glaciers might then readily 

 have been formed in the extreme western sections ot the State, or 

 at least in Colorado, the movements and melting of which pro- 

 duced the drift and gravel beds that are found in so many places 

 overlying the Loess. The rivers might then have been worn 

 down much below their present level, and even, in places, to bed- 

 rock. After the opposite or descending movement commenced, 

 the rivers again silted up their beds. This silting up continued to 

 recent times. At present the indications are that there is a slight 



