58 TARR AND MARTIN CHANGES OF LEVEL IN YAKIJTAT REGION 



not traceable to a single sharp break, but are apparently the result of 

 decided change taking place in a narrow zone. 



It would be interesting to know what effect a 34-foot uplift had on the 

 crevassed front of Turner glacier, for there is evidence of this great eleva- 

 tion up to the very edge of the ice. Gilbert suggests that the front of this 

 glacier is floating, and if this is true the effects of uplift would have been 

 more destructive than if the ice rested on the bed of the fiord. We were 

 unable to determine what effect the uplift had; but it is noteworthy that 

 the form of the ice-front has been materially changed since Gilbert photo- 

 graphed it in 1899. 



CHANGES OF LEVEL IN THE NORTHWEST ARM OF RUSSELL FIORD 



The northeastern shore of this fiord, from the Hubbard glacier to Nun- 

 atak fiord, shows uniformly an uplift of considerable amount (plate 15, 

 figures 1 and 2) ; but the conditions for accurate measurement of the 

 uplift were not usually present on the friable slate rock and extensive 

 beaches which constitute this shore. Four good observations were secured, 

 one of them on the beach (7 feet 7 inches), the other three on barnacles 

 on the rock (plate 17, figure 1), giving measurements of 7 feet 1 inch, 

 7 feet 6 inches, and 9 feet. It is along this coast that an older beach, 

 covered with mature alders, was discovered (see figure 1). 



On the southwest shore, on the other hand, although the rocks are very 

 favorable for preservation of barnacles, we nowhere found evidence, either 

 of a physiographic or a biologic nature, of uplift of over 2 feet. On 

 most of the coast the evidence is wholly negative, but at four points we 

 found dead barnacles on a slightly elevated bench from 1 foot to 1 foot 

 10 inches above the highest living barnacles. The evidence is convinc- 

 ing that there is a marked difference in the uplift on the two sides of this 

 narrow, straight stretch of fiord. 



NUNATAK FIORD 



We have already described the conditions on the southern shore of 

 Nunatak fiord, where there is no clear proof of change of level, but a possi- 

 bility of an uplift of a foot or less. The northern shore of the fiord like- 

 wise gave no proof of change of level ; but this coast is wholly beach and 

 alluvial fan on which a moderate uplift might easily be indistinguishable. 

 The difficulty of discovering an elevated shoreline in this part of the fiord 

 is increased by the fact that the recession of the glacier has been so recent 

 that abundant vegetation has not advanced far up the fiord, and this aid 

 to detection of uplifted beaches is therefore absent. However, the fact 

 that no evidence of change of level could be discovered in this fiord, while 



