POSSIBLE ECONOMIC EFFECTS 285 



The advancing ice pushes against and overrides deposits previously 

 made. It also buries and mixes with the deposits of debris the battered 

 fragments of both bushes and trees which grew in front and on the sur- 

 face of the glaciers (plates 31-23). Under the variable and ever- 

 changing conditions accompanying this deposit and overriding, there is 

 being accumulated a remarkable deposit of stratified and unstratified ma- 

 terial mixed with plant fragments. 



Possible economic Effects 



In this unsettled region the economic effects of the sudden advance of 

 the glaciers have not been of marked importance ; but if the advance ex- 

 tends to the entire Malaspina and to the Hubbard and Turner glaciers, 

 there may result some effects of distinct importance to man. Already 

 the ice-cliff of Turner glacier has been extended fully a mile (plates 11 

 and 12) and the area of iceberg discharge thereby greatly increased. If 

 Turner and Hubbard glaciers also push forward, the amount of ice dis- 

 charged into Yakutat bay may far exceed that of the present. If Malas- 

 pina glacier advances far enough to enter Yakutat bay and the Pacific 

 ocean, as it may possibly do, the discharge of icebergs will constitute a 

 menace to navigation along this coast. 



Farther to the northwest the toAvn of Valdez is situated on an alluvial 

 fan directly in front of Valdez glacier. If earthquake effects should start 

 a wave of glacier advance there similar to that Avitnessed in the Yakutat 

 Bay region, that city would be in danger both from the advancing ice and 

 from the increased volume of water discharged from it. 



In several places in Alaska trails extend over glaciers, and such an ad- 

 vance as that in the Yakutat Bay region would of course destroy these. 

 In the consideration of routes for railroads, it is proposed, in some in- 

 stances, to lay the tracks over or near the terminus of stagnant glaciers. 

 Such a sudden advance of glaciers as is described above would of course 

 completely interrupt travel along such routes. In this region of frequent 

 earthquakes it is not at all unlikely that glaciers of other sections may 

 during the present century receive an impulse of advance similar to that 

 which has visited the Yakutat Bay region. If is certainly a possibility 

 which ought to be taken into consideration in building towns, roads, and 

 railways. 



Conclusion 



In a region where the recent history of the glaciers has been almost 

 uniformly one of recession, such a sudden advance as has been described 

 in this paper is of interest and importance. So far as is known to the 



