62 TARR AND MARTIN CHANGES OF LEVEL IN YAKUTAT REGION 



bay seem to demand at least two lines of faulting. One of these (see 

 line C, plate 23) is inferred between Haenke island and the west shore, 

 one (line D, plate 23) between Haenke island and the east shore. No 

 other evidence of these inferred faults was discovered than the remarkable 

 differences in uplift in short distances. The rapid descent of the ele- 

 vated shoreline from 17 feet to no change at Gilbert point is believed to 

 be related to the fault line along the northwest arm of Eussell fiord. 



FAULT LINE IN NORTHWEST ARM OF RUSSELL FIORD 



It has already been shown that geological structure indicates the exist- 

 ence of an older line of faulting along this straight reach ; that an uplifted 

 beach of older date exists on the northeast shore, but none was discovered 

 on the southwest shore ; and that the uplift of 1899 upraised the northeast 

 shore from 7 to 9 feet and the southwest shore nowhere more than 1 foot 

 10 inches, so far as we could see. These facts point clearly to a fault line 

 along the axis of this part of the fiord (see fault line E, plate 23). 



Nunatak fiord gives us no proof of change of level, though the nunatak 

 at its head is badly fractured. 



SOUTH ARM OF RUSSELL FIORD 



From a region of very slight uplift near cape Enchantment, and a pos- 

 sible slight uplift on the opposite shore, there is a rise in the elevated 

 shore line to a maximum of 10 feet near the head of the inlet, where in a 

 short distance the uplift is abruptly replaced by depression on the fore- 

 land along the line of the inferred mountain-front fault (line A, plate 

 23). There is no evidence of faulting along the axis of this part of the 

 fiord ; and no proof of an earlier uplift was discovered. 



MINOR FAULTING 



In addition to the major lines of faulting which we have inferred, evi- 

 dence exists at several widely scattered points proving a minor shattering 

 of the crust, as stated in the preceding paragraphs. These places have 

 in no case been found along the lines of inferred major faults, but in all 

 cases where observed the}^ appear to be due to a minor shattering in the 

 larger uplifted blocks. The fact that no uplifted shorelines occur near 

 the shattered Gannett nunatak is not significant, since the present coast 

 of the nunatak was more nearly inclosed by ice in 1899, and a few years 

 previous to that (in 1891) was completely inclosed; so that by 1899 there 

 had not been opportunity for the development of a shoreline on the 

 nunatak. 



FOLDING VERSUS FAULTING 



Both in the field and since our return we have attempted to place the 

 interpretation of folding on the phenomena of deformation described, but 



