272 R. S. TARR RECENT ADVANCE OF GLACIERS IN ALASKA 



the alder growth on the glacier was being destroyed, the soil being re- 

 moved from around the roots, and the bushes themselves lowered into the 

 crevasses. 



Later in the summer we approached Atrevida glacier again, this time 

 from the western side, where we looked down on it from Terrace point 

 (plates 19 and 15, figure 3). From here it was evident that the ice 

 was pushing up against the margin of Terrace point, and it was found 

 that it had moved forward far enoiigh to cover the camp site which 

 Messrs Martin and Butler had occupied in the previous summer. We 

 have no means of telling exactly how far the ice-margin had pushed for- 

 ward here, but it had evidently advanced several hundred yards. Farther 

 southward the Atrevida had pushed out into the morainic waste of the 

 stagnant Lucia glacier, and its crevassed margin was distinctly higher 

 than in the previous summer, when the unbroken, undulating surface was 

 not noticeably different either in character or in level from that of the 

 Lucia (plate 17, figure 2). 



Contrast with Lucia glacier. ^Kccor ding to Mr Butler, who was on 

 both expeditions, the lower stagnant portion of Lucia glacier shows n«o 

 change in the ten months between the two visits to it (plate 17, figure 3). 

 He believes, however, that above Floral pass there is far more crevassed 

 ice than there was in 1905. It is therefore possible that a wave of ad- 

 vance is in progress in the Lucia, but that it has not yet a:ffected the 

 expanded lower portion. Being a much longer glacier than the Atrevida, 

 the Lucia might well be expected to respond more slowly to the impulse 

 which caused the 1906 forward movement of the Atrevida and the still 

 earlier advance of the Galiano. 



Past and future. — In the case of Atrevida glacier, a long period of 

 repose and wasting has terminated in a sudden forward rush of such force 

 as to break the ice into an impassable sea of crevasses. We do not know 

 how long this period of repose had lasted. It certainly dates back before 

 Russell's crossing in 1890, and judging from the maturity of the fringing 

 forest and of the alder growth on its outer portion, it seems probable that 

 this part of the glacier has been essentially stagnant and slowly ' wasting 

 for not less than half a century. At the time of our visit, the forward 

 thrust had not yet reached its maximum, and therefore we cannot tell 

 how much farther it will extend ; nor can we predict whether its effects in 

 breaking the ice will outlast the first rapid forward rush. If the Galiano 

 glacier may be taken as a guide, however, it may be expected that the 

 forward movement will be short-lived and quickly followed by a period 



