National Institute of Informatics - Digital Silk Road Project
Digital Archive of Toyo Bunko Rare Books

Glacis of
gravel
northward.

I ascended the slope sufficiently far to make sure that rows of high clay terraces, just like those
we had skirted, abutted on the foot of the Sai for a distance of at least four miles eastward. Above
this wide glacis of piedmont gravel there rose only a few scattered terraces of reddish clay of no
great height, showing that the soil underlying the cover of coarse gravel was the same here as that
from which the rows of Mesas had been carved out within the basin southward. No trace of
vegetation, living or dead, could be seen anywhere on this desolate Sai ; nor could we, scanning
its surface with our glasses, discover any signs of well-defined drainage channels across it. As seen
from the Mesas that we ascended, the gravel slope to the north-east stretched away unbroken with
an apparently very uniform gradient right up to the horizon. To the north only low isolated hills
showed above it in the distance. It seemed clear that from those sides no drainage could reach
the basin sufficient to account for all the moisture shown by its surface.

Length of
Mesas.

After having thus reconnoitred the northern limit of the basin, we turned to the south-south-
east and marched along the gravel-strewn trough between two rows of high Mesas. The longi-
tudinal extension of the Mesas is illustrated by the fact that, while thus moving for a distance
of over two miles, I noticed only one gap in the Mesa row on our left through which it might have
been possible to take our camels. After that distance had been covered, vegetation appeared
again in the shape of some thorny scrub growing on a few small hillocks of sand, and there we
camped for the night. The attempt at a well was abandoned as the soil composed of mixed gravel
and sand showed no signs of moisture after we had dug down a few feet.

Formation
of Mesas.

The night of March 14th to 15th brought a violent storm from the south-west, which cleared
the atmosphere completely. As a result, the view obtained when in the early morning we ascended
a prominent Mesa, probably about a hundred and fifty feet in height, just south of our camp, was
exceptionally comprehensive. All round us it showed serried lines of Mesas, built up of layers
of reddish-brown clay with much thinner strata of yellow sandstone between. The panoramic
view reproduced in Figs. 184–6 well illustrates the varied shapes of these Mesas, and also shows
how wind-erosion attacking the softer sandstone strata undercuts the more solid clay and gradually
breaks up the long ridges into smaller terraces and knolls.

Southern
edge of
lacustrine
basin.

Besides the big area of Mesas in which we stood, two other belts of them, narrower but longer,
could be made out eastwards. These, too, were obviously comprised within the limits of the ancient
lacustrine basin extending between the foot of the gravel glacis northward and the line of high
sands on the south. From our elevated point of observation I could clearly see that this line of big
dunes was continued on the south-east by a long flat plateau of Sai, and our mapping of 1907 left
no doubt that behind this there lay the end of the Su-lo-ho course, as then surveyed.⁹ But of a
gap in this plateau by which the waters of the dying Su-lo-ho might reach the basin, as then con-
jecturally assumed, no indication was to be discovered.

Snowy
mountains
sighted.

Far away to the south there stood up in glittering snowy whiteness the great range of mountains
from above Tun-huang to Anambar-ula. It was a very imposing sight, which occasional clear
views obtained in the course of my explorations along the Tun-huang Limes had impressed on my
memory. The night's storm had deposited a light sprinkling of snow, too, on some of the low desert
hills rising above the dark gravel glacis to the north. But this soon disappeared as the sun rose
higher. The panorama around me was on a vaster scale and, in spite of its utter desolation, more
varied than any my eyes had rested upon in Central-Asian plains.

South-
eastern
portion of
basin.

Satisfied as to the character and limits of the north-western portion of the basin, I now decided
to reconnoitre it in the south-east. After moving for about two miles southward between rows of
Mesas, we emerged on a level plain of sand fringed by clay terraces which wind-erosion had reduced