| 5c ACROSS THE HINDUKUSH CH. III indeed that these accumulations of debris were being steadily if slowly carried onwards. But even there the exposed ice surface looked almost black, and when at the Otrughul glacier (Fig. 23) I had under serious difficulties clambered up for some five miles from the snout to an elevation of about i 6,000 feet, the reaches of clear ice and snow descending from the buttresses of a peak over 23,000 feet high seemed still as far away as ever. Two years later, coming from explorations on the desolate high plateaux of north-western Tibet, I was able to climb up to the flank of this snowy peak and to sight from the watershed, at an elevation of 20,000 feet, the névé beds which give rise to this great glacier. How I reached the snowy cornice of the crest (Fig. 24) after a long climb up a much-crevassed glacier and lost there the toes of my right foot is another story and need not be told again here. The huge accumulations of debris which cover all glaciers of the K`un-lun probably help to account for the important part which the survival in those glaciers of `fossil' ice from the last glacial period and its gradual reduction during the last few thousand years may, according to the theory mentioned in the preceding chapter, be assumed to play as regards the volume of the rivers fed by those glaciers and hence as regards the extent of irrigation obtainable from these rivers within the oases. Old moraines of huge size could be traced clearly at the head of the Nissa valley (Fig. 25) down for about three miles below the present foot of the Kashkul glacier, at an elevation of about 13,000 feet. Thick layers of fine loess dust deposited since ages by heavy clouds of dust, such as we saw again and again swept up by the north wind from the great desert | 
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