RESEARCHES IN ALASKA 



559 



of such form as to support our 

 belief that all these fiords have 

 been chiefly widened and deep- 

 ened by glacial erosion. The 

 submarine topography in each 

 case was not greatly different 

 from that above sea-level. Some 

 rock basins were also eroded 

 in the fiord bottoms, but these 

 and the submerged moraines are 

 hard to distinguish by soundings 

 alone. 



Many other submerged hang- 

 ing valleys were discovered in 

 soundings, as Granite Cove and 

 the channel east of Heather 

 Island, near Columbia Glacier; 

 Siwash Bay, in Unakwik Inlet ; 

 Yale Arm of College Fiord; the 

 cove near Tebenkof Glacier, in 

 Blackstone Bay ; the cove of 

 Serpentine Glacier, in Harriman 

 Fiord ; Nunatak Fiord, Seal Bay, 

 and the channel east of Haenke 

 Island, in Yakutat Bay, and 

 many others. 



The submerged moraines which 

 we found were of three types. 

 The first type is the moraine 

 bar, rising nearly to or just 

 above sea-level, and like the fa- 

 miliar sand bar or pair of spits, 

 except that it is made up of 

 angular striated boulders of vari- 

 ous sizes instead of pebbles and 

 sand. It differs from the reces- 

 sional moraine on the land, too, 

 in having most of the clay in its 

 till washed away by the tides. 

 Such moraine bars are found in 

 Unakwik Inlet and Blackstone 

 Bay. 



The second type of moraines 

 is partly revealed without sound- 

 ing and may be deeply sub- 

 merged in the middle, but with 

 normal sand pits growing upon the mo- 

 raines near shore, as at the mouths of 

 College Fiord and Barry Arm. These 

 moraines may also have their positions 

 suggested by irregular shoals or by the 

 stranding of icebergs, as on the sites 

 where Barry and Nunatak glaciers stood 

 in 1899. 



z 1 k o 

 I I I 1 I 



6 miles 



MAP SHOWING SOUNDINGS IN PORT WELLS, PRINCE 

 WILLIAM SOUND 



Illustrating a typical day's work in the study of sub- 

 marine topography (see page 558) 



The third type of submerged moraine 

 is entirely unsuspected until revealed by 

 sounding, as in College Fiord, opposite 

 Smith and Bryn Mawr glaciers. It was 

 gratifying to find such a submerged mo- 

 raine in lower Russell Fiord in 19 10 ex- 

 actly where we had previously postulated 

 a halt of the ice because of overridden 



