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THE NATIONAL GEOGRAPHIC MAGAZINE 



glacial deposits to the north and aban- 

 doned glacial lake shore lines to the 

 south. 



The nature of the glacial deposits ac- 

 cumulating now in shallow water is easy 

 to see, as in Russell Fiord, near Yakutat, 

 where the sands and clays of Hidden 

 Glacier delta have grown forward 1,600 

 feet between 1899 and 1910, and in Har- 

 riman Fiord, where one can land at low 

 tide on the till and boulder moraine 

 shoals which were being built by Barry 

 Glacier only 1 1 years ago, when the Har- 

 riman expedition was here. In more 

 profound depths we know less about 

 these deposits, except that they must be 

 mostly muds and clays in these deep 

 waters, with scattered stones dropped by 

 floating icebergs. There are many other 

 illustrations of each of the glacial fea- 

 tures cited above, but the ones mentioned 

 here must suffice as samples until the 

 complete book on our glacial studies is 

 published. 



the; glaciers are remnants of giant 



PREDECESSORS 



In Prince William Sound a few points 

 stand out clearly in connection with the 

 former great glaciers that flooded this 

 arm of the sea when the existing glaciers 

 were much more expanded. It is clear 

 that they filled the whole sound, rising 

 up in the present fiords high above the 

 level of the existing glaciers, perhaps 

 4,000 feet above sea-level near Columbia 

 Glacier and Port Wells. They did not 

 cover all of Hinchinbrook and Montague 

 islands, at the entrance of the sound, and 

 these mountainous islands are largely 

 driftless, as we proved by observations 

 there, and formerly rose as nunataks 

 through a piedmont glacier that extended 

 out, as Malaspina Glacier does now, and 

 probably reached Middleton Island, 55 

 miles offshore, ending in the Pacific with 

 a great tidal ice front similar to the great 

 snow barriers of the Antarctic region. 



The existing glaciers are shrunken 

 remnants of their great predecessors, 

 and are largest near the highest moun- 

 tains and greatest snowfields and very 

 small in the lower regions, as on Knight 

 and Montague islands. 



The expanded glaciers eroded deeply, 

 rounding the overridden islands in the 

 north part and sculpturing the whole 

 sound, which is 1,500 to 2,400 feet deep 

 in some of the inner stretches and 1,200 

 to 1,300 feet deep in Hinchinbrook en- 

 trance, where the ice was constricted 

 and moved rapidly, while the adjacent 

 sea bottom of the Pacific is shallow, 200 

 to 300 feet, for over 50 miles offshore. 

 Glacial deposits above sea-level are thin 

 and scattered in Prince William Sound. 

 The great work of the ice was erosion, 

 with deposition mainly offshore. Dense 

 mature forests extend up close to the 

 present ice fronts, and there has been no 

 episode of recent great expansion of gla- 

 ciers, as in Yakutat Bay, though minor 

 oscillations have, and still are, taking 

 place. 



The Copper River glaciers were also 

 greatly expanded in the past and modi- 

 fied the valley profoundly. There is rea- 

 son for thinking that the former great 

 glaciers of the Wrangell Mountains and 

 Alaska Range did not find an outlet 

 down this valley, though much of the 

 drainage may have come this way. Mr. 

 Alfred H. Brooks, of the Geological Sur- 

 vey, had called my attention to peculiari- 

 ties of this drainage, and I am inclined 

 to think, after a brief journey up the 

 Copper River to the mouth of the Chit- 

 nia, that the present course of Copper 

 River across the Chugach coast range is 

 entirely due to glacial modifications in a 

 way to be explained in the forthcoming 

 book. 



The glacier studies in 1910 carry the 

 previous researches by the National Geo- 

 graphic Society much farther than in 

 1909, supplementing the facts already 

 established in Yakutat Bay, and their 

 interpretation, and adding new data of 

 considerable importance in glacialogy. 



ACKNOWLEDGMENTS 



THE National Geographic Society has 

 much pleasure in expressing its thanks 

 and appreciation to the following com- 

 panies and individuals for material assistance 

 rendered to its Alaskan expeditions : 



Copper River & Northwestern Railway Co., 

 Cordova, Alaska — transportation, subsistence, 

 maps, storing launch for v/inter, etc. 



