262 R. S. TARR RECENT ADVANCE OF GLACIERS IN ALASKA 



change will now be more definite!}' stated for each of the glaciers con- 

 cerned. 



The ADVANCING Glaciers 



VARIEGATED GLACIER 



Condition in 1905. — Variegated glacier (plates 8-10), having its 

 source far back in the mountains, descends in a serpentine course through 

 a valley greatly steej^ened by glacial erosion (plate 8, figure 2). On 

 emerging from its mountain valley, the glacier expands into a broad, 

 bulb-shaped area which extends westward until it coalesces with Hubbard 

 glacier, and southwestward. almost to the sea. 



In August, 1905, this glacier was studied with some care, especially 

 in its bulb-shaped expansion outside of the mountain front, which pre- 

 sented some interesting morainic phenomena. We walked freely over 

 the bulb-shaped terminus and ascended the valley glacier to a point 6 

 miles or more from the sea. At that time all parts of the glacier visited 

 were easily traversed and possessed no areas of marked crevassing. In 

 the middle of August the snowline on the glacier was at an elevation of 

 approximately 2,200 feet. At and above snowline there was some 

 crevassing, but not enough to impede travel as far up as we went. In 

 this upper portion numerous small tributary glaciers descended by steep 

 grades from hanging valleys. 



Below snoAvline the glacier surface was rapidly melting, and toward 

 the end of the mountain valley it was littered with angular rock frag- 

 ments. Everywhere the surface was so smooth that one could travel in 

 a straight course over it with almost no detours on accoimt of crevasses 

 (plate 9, figure 1). The slope of the valley portion of the glacier 

 varied from 7 to 10 degrees, but flattened decidedly near the end of the 

 mountain valley, where in places the grade was even reversed. 



On emerging from this mountain valley Variegated glacier expanded 

 abruptly and, through ablation, became covered with an almost contin- 

 uous sheet of moraine. This morainic veneer varied in thickness, causing 

 a succession of ridges and intermediate depressions arranged concentric- 

 ally (plate 9). These concentric ridges, which roughly paralleled the 

 bulb-shape of the expanded ice-foot, consisted of rocks of various kinds 

 and colors, giving rise to a remarkable series of crescentic moraines whose 

 characteristics we studied with some care. The outer portion of the ex- 

 panded ice-foot, near the sea, was so stagnant and so deeply covered by 

 moraine that scattered willows and alders were growing on it, and the 



