Oct. 1849. MOVEMENT OF SLOPES OF DEBPJS. 179 



at the very summit, with frozen snow amongst them, 

 beyond which the ice and precipices rendered it impossible 

 to proceed : but though exposed to the north, there was no 

 perpetual snow in the ordinary acceptation of the term, and 

 an arctic European lichen (Lecidea oreina) grew on the 

 top, so faintly discolouring the rocks as hardly to be 

 detected without a magnify ing-glass. 



I descended obliquely, down a very steep slope of 35°, over 

 upwards of a thousand feet of debris, the blocks on which 

 were so loosely poised on one another, that it was neces- 

 sary to proceed with the utmost circumspection, for I was 

 alone, and a false step would almost certainly have been 

 fohWed by breaking a leg. The alternate freezing and 

 thawing of rain amongst these masses, must produce a con- 

 stant downward motion in the whole pile of debris (which 

 was upwards of 2000 feet high), and may account for the 

 otherwise unexplained phenomenon of continuous shoots of 

 angular rocks reposing on very gentle slopes in other places.* 



The north ascent to the Donkia pass is by a path well 

 selected amongst immense angular masses of rock, and over 

 vast piles of debris : the strike on this, the north face, was 

 again north-east, and dip north-west. I arrived at the top 

 at 3 p.m., throughly fatigued, and found my faithful Lepcha 

 lads (Cheytoong and Bassebo) nestling under a rock with 

 my theodolite and barometers, having been awaiting my 

 arrival in the biting wind for three hours. My pony 

 stood there too, the picture of patience, and laden with 



* May not the origin of the streams of quartz blocks that fill gently sloping 

 broad valleys several miles long, in the Falkland Islands, be thus explained ] (See 

 ■ " Darwin's Journal," in Murray's Home and Col. Lib.) The extraordinary shifting 

 in the position of my thermometer left among the rocks of the Donkia pass 

 (see p. 129), and the mobile state of the slopes I descended on this occasion, first 

 suggested this explanation to me. When in the Falkland Islands I was wholly 

 unable to offer any explanation of the phenomenon there, to which my attention 



had been drawn by Mr. Darwin's narrative. 



n 2 



