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(A. 1) to the south of Lo-t'o-ching (D. 3),
appears to correspond in position and con-
figuration to the first four ranges of the
Pei-shan, described and mapped by Professor
Futterer on his route from west of Ming-
shui to the Su-lo-ho bend. 27

Just as is the case on this far more
westerly route, the second and third of the
ranges, encountered by us north of Camps
212 and 209 respectively (B. 2, C. 3), showed
the highest pass-levels, but without any
strikingly great elevations above either pass. 28
Whereas, however, on Prof. Futterer's route-
line the wide valleys or plateaus separating
the ranges all seem to descend gently west-
ward, those crossed by our route invariably
appeared to have their drainage to the east
or north-east, i.e., in the direction of the
Etsin-gol valley and basin. The chain of
low hills shown on our map extending north
of the Su-lo-ho bend and the Hua-hai-tzu
depression, and an easterly continuation
crossed by our routes from Mao-mei (Sheet
No. 42. B, C. 3), evidently represent the
fifth and southernmost Pei-shan range.

The zone in the southern part of the
sheet shows several geographically interest-
ing features. In the west we have the head
of the lower Su-lo-ho valley, below the
river's debouchure from the mountains.
Further down (A. 4) its bed is hemmed in
by a well-marked defile between the bold
Wang-shan-tzu ridge, representing the east-
ern extremity of the outermost Nan-shan
chain on the south, and a flat spur of the
southernmost Pei-shan range on the north.

Into the basin-like head of the lower Su-
lo-ho valley thus formed, there slopes down
the almost imperceptible watershed, dividing
it from the plateau between the two outer hill
chains of the Nan-shan, which contains the
small oases of T'a-shih and Ch'iao-tzu (A. 5).
The latter derives its irrigation from springs,

and the existence of a large ruined site above
these, at the foot of a gravel glacis sloping
down from the outer Nan-shan range to the
south, here offers clear evidence of desicca-
tion within historical times. 29 Whether
this outer range, the second from the north,
has a traceable continuation eastward on the
wide gravel glacis sloping up towards the
Su-lo-ho debouchure remains doubtful.

The oasis of Yü-mên-hsien (C. 5) derives
its name from the ancient 'Jade Gate'
(Yü-mên) of the Limes, originally situated
in Han times far to the west of Tun-huang
(No. 35. D. 4). Its cultivation stretches
down to the neighbourhood of a practically
level flat of scrubby, and in parts boggy,
ground dividing the Su-lo-ho valley from
the Hua-hai-tzu depression eastwards. This
peculiar feature accounts for the curious
bifurcation previously mentioned by which
the Su-lo-ho, partly through irrigation
channels and partly through inundation in
the season of floods, feeds a stream flowing
past the hamlets of Shih-êrh-tun and Shih-
tun into the Hua-hai-tzu basin. 30

This last named basin (D. 5) is a drain-
ageless area, bordered in the north by the
foot of the outermost Pei-shan range and in
the south by a rugged hill-chain which
trends to the south-east and attains its
greatest height near Chia-yü-kuan west of
Su-chou (No. 43 A. 1). The relation of
this hill-chain to the Ala-shan mountain
system, of which it appears like an extreme
western continuation, must remain for the
present doubtful. Apart from the stream
below Yü-mên-hsien there drain into the
Hua-hai-tzu basin the rivers of Ch'ih-chin
and Po-yang-ho, coming from the Nan-shan
and cutting through the hill chain just
named in deep gorges. The subsoil drainage
from the former gathers in springs below
its alluvial fan and supplies irrigation to the