RESEARCHES IN ALASKA 



551 



lake was formed where there was only 

 a marginal stream in 1909. At the out- 

 let of this lake^ the turf covering the 

 glacial deposits, which were being pushed 

 forward by the advancing glacier, was 

 gashed with irregular cracks where the 

 former covering of the soil had proved 

 too small to fit the bulging hill. Between 

 June and September, 1910, when we re- 

 visited Columbia Glacier, the waterfall at 

 the lower end of this lake was cut back, 

 the lake level was lowered a little, and 

 the stream-course shifted. 



As at Childs Glacier, the advance was 

 not spectacular, and noises were absent. 

 One could clamber all over the advanc- 

 ing margin of the glacier. From one 

 day to the next, however, we saw great 

 changes, as when a part of the ice front 

 was seven feet from a blazed tree on 

 July 6 and touched the tree on July 9. 



From July to September the changes 

 were*far more noticeable, the most spec- 

 tacular transformation being the decrease 

 in height of a portion of the glacier from 

 about 60 feet to less than 15 feet, while 

 its margin in the same place advanced. 

 If this was due to melting it was at the 

 rate of nine inches a day, taken off by 

 vertical ablation. The measured rates 

 of surface melting on other glaciers in 

 Alaska are one, two, four, and seven 

 inches a day, all on retreating glaciers. 

 As the terminus of the glacier was ad- 

 vancing, we think it probable that there 

 may have been a collapse of this portion 

 of the glacier surface by the moving 

 away of the ice beneath — a phenomenon 

 exceedingly suggestive of viscous flow- 

 age. 



West of Columbia Glacier in Unakwik 

 Inlet is Meares Glacier, the north side of 

 which advanced slightly between 1909 

 and 1910. This is the glacier which the 

 Spanish explorer Fidalgo, in 1790, called 

 a volcano, because of the discharge of 

 icebergs from below sea-level with thun- 

 dering reports. Above it rises Mount 

 Grosvenor, named for the National Geo- 

 graphic Society's Director and Editor. 



In the northwest corner of Prince 

 William Sound is Port Wells, a broad 

 fiord whose branches — College Fiord, 



Harriman Fiord, and Passage Canal — 

 contain large glaciers. In College Fiord 

 seven glaciers were advancing simultane- 

 ously in 19 10, two of them perhaps com- 

 mencing in 1909, as observed by Grant. 

 The Harvard, Yale, Radcliffe, Smith, 

 Bryn Mawr, and Wellesley glaciers dis- 

 played activities similar to that of Childs 

 and Columbia glaciers, after having been 

 stagnant for a long time before. Yale 

 Glacier had advanced 750 feet in all since 

 1899, when it was studied by the Harri- 

 man expedition and mapped by Gannett. 

 All these glaciers were destroying the 

 forests at and upon their margins, and 

 splinters of ice were being pushed for- 

 ward by faulting, as at Columbia Glacier. 



Harriman Glacier was the only one in 

 the fiord of that name which was ad- 

 vancing in 1910, having come forward 

 300 feet since 1899. In Blackstone Bay, 

 a branch of Passage Canal, several of the 

 glaciers are advancing. 



RETREATING GLACIERS 



Below Mount Gannett in Harriman 

 Fiord is the Barry Glacier, which nearly 

 separated that body of water from the 

 sea in 1899, when the Harriman expedi- 

 tion discovered and explored it. Between 

 1899 and 1910 Barry Glacier retreated 

 about 3^2 miles, as is shown on page 

 550, where Gannett's map is reproduced 

 with the latest one. Approximately 600 

 feet of this retreat took place between 

 Grant's visit in 1909 and ours a year 

 later. Moraine-veneered ice was still 

 present in 19 10 on the site of the margin 

 of the glacier in 1899, over two miles 

 from the present ice front. Surprise 

 Glacier went back a mile and a quarter 

 in this same period of 11 years. 



Tiger Glacier in Icy Bay was short- 

 ened about seven miles between 1794, 

 when Vancouver's lieutenant, Whidbey, 

 mapped it, and our visit in 1910. Not 

 only has the fiord been lengthened by 

 this amount, but the Icy Bay glacier of 

 1794 has been dismembered into the 

 Tiger, Chenega, and Princeton glaciers. 

 Valdez and Shoup glaciers had retreated 

 slightly since 1909. Nellie Juan Glacier 

 was little changed. Many other glaciers 



