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old valleys which, during the ice-flood period, were pro- 

 foundly modified, the glacial erosion extending far below 

 sea level, widening the valley, aligning its walls, and 

 smoothing them out into wide sweeping curves; in brief, 

 sculpturing the land into forms in harmony with the stiff, 

 non-pliable nature of the eroding ice streams confined 

 within the valley. As a result, the topography bears 

 everywhere the marks of most intense glaciation. Of the 

 distinctive features of glacial erosion on a tremendous 

 scale, the following are characteristically developed in 

 Southeastern Alaska: — U-trough shape of cross section 

 of valley; straightening of valley course; glacial grooves 

 and markings along valley sides and bottom ; ; steep valley 

 head, often with cirque termination; hanging valleys; 

 steep valley walls, in places overhanging and showing 

 double slopes; alignment of cliff bases; glacial junction 

 spurs; grade of valley floor, in places overdeepened ; 

 knolls of bed rock projecting above the valley floor ; roches 

 moutonnees, etc. The noticeable absence of moraines in 

 this area of intense glaciation is due chiefly to the peculiar 

 steepness of the mountain and valley slopes, which are 

 often oversteepened and so uneven, that, except for the 

 river deltas and flats, it is difficult to find a flat area a 

 single square mile in extent in all the 40,000 square miles 

 (100,000 sq. km.) of land area in Southeastern Alaska. 



The fiords pass at their heads over broad tidal flats 

 into wide floored valleys, densely forested, and exhibiting 

 everywhere profound ice erosional features. The valleys 

 in turn are usually terminated by cirques in which a small 

 glacier may still be present, the original glacier, which 

 filled the valley to a depth of 4,000 to 6,000 feet (1,200 to 

 1,800 m.) having dwindled to the present miniature 

 glacier, which is ineffective and incapable of accomplishing 

 the prodigious feats of erosion which it performed during 

 the ice deluge. Farther to the north and west, in Glacier 

 bay and Yakutat bay, the glaciers are larger and more 

 impressive, but, compared with the great ice masses which 

 were active during the period of maximum ice extension, 

 they are mere pigmies. The land forms over the entire 

 area indicate an intensely glaciated region which has been 

 but slightly modified by water erosion since the Glacial 

 epoch. At the time of maximum ice flooding, the ice sheet 

 covered the whole archipelago with the exception of 

 isolated high peaks, which can be recognized at present 

 as having been above the ice sheet, by their sharp serrated 



