LAKE PANGONG 69
apparently in origin also, the valley lakes of the Pangong series are of the same type as the famous lakes of Switzerland, the lochs of Scotland, and the fiords of Norway. Many geologists believe that such lakes and fiords are due to the work of glaciers. The streams of ice are supposed to deepen and broaden certain parts of their channels more rapidly than other parts. Thus relative depressions are formed, which are converted into lakes when the ice. retires. Other geologists hold that this is impossible; for, if it were so, there surely would be similar lakes among the intensely glaciated regions of the Himalayas. The discovery there that one such lake lies in a valley formerly occupied by a huge glacier detracts from the force of the objection. Apparently, the number is not larger because, as I saw in the Shyok valley and one or two other cases, most of the streams flow at right angles to the mountains, and have such steep grades that, in spite of the deep erosion of the glaciers, the streams have been able with equal rapidity to cut gorges through the relative elevations in the valley bottoms, which would otherwise cause lakes to accumulate above them. The Pangong valley, on the other hand, runs parallel to the mountain ranges, and has a gentle grade, so that the cutting power of its stream has always been less than that of the transverse streams.
The most important geographic feature of Pangong, so far as human relations are concerned, is the evidence
which it affords of recent climatic changes. Old beaches and lake deposits indicate that after the great changes in climate which gave rise to the glaciers that scoured out the basin now occupied by the lakes, there were other changes
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