[52 I. '. RUSSEL1 I'RFACE GEOLOGY OF ALASKA. 



/ / I . i\ instance where well-defined ice streams 



i from lateral cafiona into broad valleys, and con- 



uently are u neon fined by tin- neighboring mountain slopes, they expand 

 in all directions so as to form fan-shaped or semicircular termini, Bimilar to 



the delta-like terminus of the Rhone glacier. This expansi f glacial ice, 



when ii"t encumbered l>y moraines and free to move in all directions, tat 

 place apparently without reference to the direction in which the glaciers 

 flow. The Davidson glacier furnishes a typical example of the phenomenon 

 li,-i red i". In the lower part of the gorge through which ii descends, 



it flows a littl if north. Another example, equally typical, occurs in 



a valley tributary to Taiya valley, immediately smith of Mt. Emmons. This 

 glacier flows aboul Bouthwesl down a lateral gorge and enters a broader 

 valley nearly at right angles. Like the Davidson glacier, it endsin a Dearly 

 symmetrical fan-shaped terminus. A third example of the same character 

 is furnished by the Nor ris glacier of Taku inlet, some fifteen miles east of 

 Juneau. This glacier, I am informed, flows about southeast and ends in a 

 fan-shaped ice-foot, as is well Bhown in an illustration recently published by 

 6. I Wright.* The absence of d6bris on the surface of this glacier is 

 indicated in that illustration. 



These and other examples thai might be cited seem sufficient proof that 

 Alpine glaciers, when unencumbered by moraines, expand in all directions 

 without nt'. rence to their direction of movement, and form characteristic 

 fan-shaped termini of the Rhone -lacier type when they advance on to a 



plain. 



// of Glaciers about Limn Canal. — The presence of bare fields of 



dlbris about the extremities of many of the glaciers in the neighborhood of 

 Lynn canal, indicate that the ice streams of that region are receding. This is 

 well illustrated by the bare and rugged piles of fine debris which encircle the 

 expanded foot of the Davidson glacier. Several cirques and steep glaciated 

 troughs in the sai ion, and also at various points farther south along 



the" Inland Passage," which are ban of vegetation and have recently been 



indoned by ice, bi timony in the Barae direction. The conclusion 



that the glaci< ra of southern Alaska are retreating is in harmony with < i. I . 



bservations on the recession of M uir glacier.*) This recession is 



apparently a < tinuation of the general glacial retreat initiated when the 



< lilleran r reached it- maximum expansion. 



// ' I laska and accompanying Climatic Conditions. — 



niiej the distribution of living glaciers in Alaska ami 



their dependence on existing climatic conditions are so obvious that I venture 



ii this connect ion. 



mall II lua trail ( the 



