国立情報学研究所 - ディジタル・シルクロード・プロジェクト
『東洋文庫所蔵』貴重書デジタルアーカイブ

the delta must be inundated and hidden. To some extent it may depend upon the
material brought down by the Gyuma-chu that the lake is more shallow outside of
the delta than, for instance, south of Camp 221. At Camp 222 the gravel wall
along the shore had a height of 3.10 m.

Leaving Langbo-nan and proceeding westwards to Chiu-gompa one has to
follow close along the shore, for here the mountains reach the very edge of
the lake, and only leave a very narrow passage open to the road. The ground is
full of blocks and gravel, everything worn round by the action of the waves. The
first solid rock is diabas in 30° N. 80° W., and a little farther on sandstone in 59°
N. 55° E. The rocks are very steep, even perpendicular, and at their foot a series of
grottoes has been caved out by the waves, as may be easily seen from their rounded
forms. Along the foot of the rocks is a belt of vegetation. Several deep-cut ra-
vines pierce the rock-front. Their slopes are often covered with clay, sand and de-
tritus, in which the rain has modelled out curious steep pyramids and cones. On
the top of some of these pyramids there is a flat block, showing that they have
been formed almost in the same way as glacier-tables, the block protecting the under-
lying soft material from destruction.

The gravel wall is only feebly developed along this part of the shore. The
breadth of the open space between the foot of the rocks and the water-line is about
20 or 30 m. At a very narrow place a road is seen crossing a little mountain spur.
It must have been in use at a time when the surface of the lake stood 1.75 m.
higher than now. At the present low water level it is superfluous. In a short open
valley Chergip-gompa is situated on a terrace. West of it the rock is sandstone and
crystalline schist in 14° N. 20° W. Farther on phyllite appears in 37° N. 20° E.
Generally the fall is towards the north, but very irregular and the rock much folded.
At the promontory with a chorten from where Chiu-gompa is visible, limestone again
appears falling 10° towards 38° N. From here to Camp 219 at the foot of Chiu-gompa
the open shore plain becomes a little broader.

In 1908, when there was much more rain than in 1907, the hydrography along
the northern shore of the Manasarovar was somewhat different. Only the lagoons at
the N.E. corner were about the same. But the effluent from the eastern lagoon had,
on July 25th, a volume of 5.25 cub. m., instead of 1.76 on August 20th, 1907,
and its breadth was almost exactly 100 m. The Gyuma-chu had 4.01 cub. m., in-
stead of 2.09 the year before. It is obvious that such great differences in affluence
to the Manasarovar from one year to another must in a very high degree influence
the height of the water level. In 1908 the lake must have received at least twice as
much water as in 1907, or probably more, as 1908 brought a good deal of rain, and
1907 hardly any at all. The two following years, 1909 and 1910, the precipitation
was still increasing and made the lake overflow through the channel into the Rakas-tal.

The road from Tokchen to Serolung-gompa follows the Samo-tsangpo down-
wards for a while, leaves the river to the right, and climbs the steep hills at the