Southern Tibet : vol.7 / 386 ページ（カラー画像）

0386	Southern Tibet : vol.7
南チベット : vol.7

248

Already in 1866 the Royal Geographical Society could congratulate themselves
on the fine and indefatigable work of Sir ANDREW WAUGH and his assistants, a
work which had carried the survey over a considerable part of the country, from
the frontier of India up to the Kara-korum, the territorial limit of Kashmir. »The
attempt to go beyond that point was discouraged by the Government, for fear of
leading to political complications.»

Captain H. H. GODWIN-AUSTEN, who already in 1861 and 1862 had accom-
plished such important work in the Kara-korum, during the summer of 1863, filled
up another blank — in the district of Panggong-tso. He also expressed in clear
words some facts that formerly were only partly known. North of the Indus, he
says,¹ from its junction with the Dras River, lies a high range of mountains which
separate the Indus drainage from that of the Shayok or Nubra River. The axis
and great mass of this range is granitic. Of the several passes leading over it into the
Shayok valley, the Chang-la has an elevation of 17,470 and the Kay-la 18,250 feet.

Above Durgo (Drugub) he found large accumulations of alluvial sands and
shingle that are seen along the large valleys of these mountains. Again his perspicacious
eye observed many signs of climatic changes. The powerful force that had accumulated
these materials was now extinct. Their formation and subsequent denudation was,
however, as yet but little understood. The level of the plateau above Drugub »could
be traced across the valley in and out of its numerous ravines in a perfectly hori-
zontal line of a different colour, where very small portions of the alluvium still ad-
hered to the slopes and precipices.» He estimates their thickness at the junction
of the Tanksi and Drugub Rivers at 1500 or 2000 feet. In the valley of Muglib
he found unmistakable signs of its having been the bed of a lake.

The low pass of Surtokh is the watershed between the Panggong-tso and
Shayok and is formed entirely by loose shingle from a southern lateral ravine. If
Panggong-tso had an effluent as formerly when the surrounding glaciers were double
their present size, the talus would be swept away; now it is growing higher every
year. A rise of 150 feet in the waters of the present lake would be sufficient to
give them an exit down the valley of Tanksi.

Old shore-lines and lines of old beaches in sandbeds proved unmistakably that
the lake had been higher at earlier epochs, and myriads of fresh-water shells, Limnæa
and Planorbis, proved that the water had been fresh. He thinks the lake existed
during the latter part of the great glacial period in the Himalayas.

Whether the scooping out of the depression in which its waters lie is due to glacial
action in the first instance, when this high region was, as is most probable, deeply over-
laid by ice and snow, is a hazardous question, and one highly problematical. From the

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