150 



Modern Recession of Glaciers. 



In Russell's visits to the Yakutat Bay region in 1890 

 and 1 89 1 he found the glaciers in a state of general recession. 

 Gilbert's observations in 1899 led him to the same con- 

 clusion, and Tarr and Martin's observations in 1905 

 showed that the glaciers were still wasting away. The 

 evidence of this condition of recession is partly from infer- 

 ence, based upon the characteristics of the glaciers and the 

 conditions at their borders, and partly from the direct 

 comparison at the later dates with observations made during 

 the earlier studies. Russell, Gilbert, and Tarr and Martin 

 have all noted the fact that many of the glaciers are 

 covered at their lower ends by ablation moraine and that in 

 some of the more stagnant portions these ablation moraines 

 bear forests. From this condition the inference is per- 

 fectly warranted that the glaciers in these regions are 

 receding. More specific, however, is the evidence around 

 the glacier borders, both at the sides, and, at the fronts of 

 those which end on the land. While forest, or at least 

 alder, extends up nearly to the front of many of the glaciers, 

 and also grows on the valley sides above them, there is, 

 near many of the glaciers, a zone at the front and just 

 above the ice surface, which is barren of vegetation. From 

 such a condition one infers that the ice has withdrawn 

 from such areas so recently that vegetation has not yet 

 had time to encroach upon it. The extent of shrinkage 

 indicated by this class of evidence varies with different 

 glaciers, but it is present to some degree in the neighbor- 

 hood of almost all the glaciers studied, and in some it 

 indicates a great and long-continued shrinkage. This 

 is particularly true in Nunatak and Russell fiords, as 

 already stated in the preceding section. Here it is certain 

 that in the last century the resession has amounted to 

 many miles. 



Recent Advances of Nine Glaciers. 



In 1905 Tarr and Martin found that, while the general 

 condition of recession characterized the great majority 

 of the Yakutat Bay glaciers, Galiano glacier presented 

 convincing evidence of change to activity in the interval 

 since it was photographed by Russell in 1890. Then it 

 had a stagnant piedmont bulb on whose ablation moraine 



