184 /. C. Rmsell — Ex'pedition to Mount St. Ellas. 



One of the tunnels leading to a dry lake-bed at the end of the 

 Hitchcock range was explored for several rods and found to be 

 a high, arching cavern following a tortuous course, and large 

 enough to allow one to drive a coach and four through it without 

 danger of collision. Its floor was formed of gravel and bowlders, 

 and its arching roof was clear ice. Here and there the courses 

 of crevasses could be traced by the stones and finer debris that 

 had fallen in from above, giving the appearance of veins in a 

 mine. The deposit on the floor of the tunnel rested upon ice, 

 and would certainly be greatly disturbed and broken up before 

 reaching a final resting place in case the glacier should melt. 

 In the lake basins, also, the sand and gravel forming their bot- 

 toms frequently rested upon substrata of ice, and are greatly 

 disturbed when the ice melts. 



At the ends of the glaciers the subglacial and intraglacial drain- 

 age issues from tunnels and forms muddy streams. These 

 usually flow out from the foot of a precipice of ice, down which 

 rills are continually trickling. The streams flowing away from 

 the glaciers are usually rapid, owing to the high grade of their 

 built-up channels, and sweep away large quantities of debris 

 which is deposited along their courses. The streams widen and 

 bifurcate as they flow seaward, and spread vast quantities of 

 bowlders, sand, and gravel over the country to the right and left, 

 not infrequently invading ^the forests and burying the still up- 

 right trees. The deposits fornled by the streams are of the 

 nature of alluvial fans, over which the waters meander in a 

 thousand channels. Where this action has taken place long 

 enough the alluvial fans end in deltas ; but shoul^l there be a 

 current in the sea, the debris is carried away and formed into 

 beaches and bars along adjacent shores. Should these glaciers 

 disappear, it is evident that these great bowlder washes would' 

 form peculiar topographic features, unsupported at the apexes, 

 and it might be perplexing to determine from whence came the 

 waters that deposited them. I am not aware that similar washes 

 have been recognized along the southern border of the Lauren- 

 tide glaciers, but they should certainly be expected to occur 

 there. 



Another very striking diff"erence in the apj^earance of the 

 glaciers above and below the snow-line is due to the prevalence 

 of debris on the lower portion. The melting that takes place 



