276 K. S. TARR RECEIPT ADVANCE OF GLACIERS IN ALASKA 



Change in subglacial stream course. — One rather peculiar effect of the 

 advancing Marvine glacier was illustrated at Blossom island, situated in 

 the bay where the western margin of the Hayden and eastern margin of 

 Marvine glaciers imite. Streams supplied from the Marvine, and from 

 several small valley glaciers, unite here to form a fairly good-sized river, 

 which, after expanding in a small lake at the ice-margin, emerges to pass 

 into a subglacial tunnel, from which it escapes as the Kwik river after a 

 Journey of 5 miles under the ice. 



Just before our visit the Blossom Island lake had been greatly enlarged, 

 covering an area several times its present size and rising 25 or 30 feet 

 above its present level. The proof of this rise was the presence of a 

 recently deposited layer of fine glacial mud, the occurrence of stranded 

 icebergs above the lake level, and the retarded development of vegetation. 

 In the areas that had been submerged the annual plants had only just 

 begun to sprout, although it was the middle of July, and the alders and 

 willows had only begun to put out their leaves, while some of the bushes 

 nearer the lake had not begun to sprout. 



In seeking a cause for this expansion of the Blossom Island lake, we 

 found that the course of the outflowing stream had been entirely changed. 

 Formerly it had flowed oi;t through a small bay in the ice at the junction 

 of Hayden and Marvine glaciers, doul)tless disappearing in an ice-tunnel. 

 The forward push of Marvine glacier had evidently destroyed this tunnel, 

 but it had not completely destroyed the bay in the ice through which the 

 water flowed on its way to the tunnel. About a mile to the north a new 

 outlet had been developed under Hayden glacier, which is not -subjected 

 to the forward thrust. The newness of this outlet was proved by the fact 

 that the great torrent of water was riishing under the glacier without the 

 development of an arch. The current licked the ice-foot at the base of a 

 cliff fully 200 feet high, from which large masses of ice were falling every 

 few minutes. Occasionally great slices, thousands of tons in weight, 

 slumped into the torrent to be swept in pieces under the glacier. By this 

 action a bay over a himdred yards long had already been eaten into the 

 glacier; and beyond this, for a distance of several hundred yards, the ice 

 under which the stream flows is broken by slumping. 



The shifting of a subglacial stream course by the advance of Marvine 

 glacier, evidently the work of the season of 1906, is therefore another of 

 the peculiar effects accompanying the remarkable advance of the glaciers 

 of this region. When the new outlet was opened it must have caused a 

 sudden increase in the volume of the Kwik. In fact, it is probable that 

 our packers witnessed it; for a cache containing most of our provisions, 



