Chap. IV] NOTES ON
those of the small oases below the glacis of the K'un-lun east of Khotan. 26 To the west and south of Nan-hu, the gravel glacis and the low ridges emerging from it are often overrun by dunes of considerable height. Further to the south rise two successive ranges which, as Sheet No. 36 shows, are continued westwards.
In the eastern portion we can distinguish three chains of which the southernmost and highest forms the outer rim as it were of the mountain wall containing the region occupied by the drainageless plateaus of Makhai and Tsaidam. In the east (D. 1) this chain is joined by another which, though lower, has its distinct continuation eastwards to the middle course of the Su-lo-ho and
Astronomically observed latitude.
1906-08. Nan-hu, Camp 168 (central hamlet, fields west of `Yâr'; A.1)
NOTES ON SHEET No. 40 (YÜ-MEN-HSIEN)
SHEET No. 39 97
beyond among the Central Nan-shan ranges.
Elsewhere, the southernmost chain sinks down with uniformly gentle slopes of detritus and gravel to the outer chain of dune-covered foothills south of Tun-huang (B,C.1). Without having seen the ground myself I am unable to judge whether on this intervening wide plateau indications can be traced of the second outer chain, that of Tung-pat`u (No. 38. D. 4) and Ch'iao-tzu (No. 40. A. 4 ), buried among the huge accumulations of detritus. Throughout the westernmost Nan-shan far-advanced decomposition is a very striking feature.
Correction. In the ` Index to adjoining sheets', Sheet Nos. 41 and 42 should read 40 and 41 respectively.
The area comprised in this sheet divides itself like that of Sheet No. 38, of which it forms the eastward continuation, into two well-defined zones. The northern and much larger one, surveyed in 1914 on a single and previously unexplored route, is occupied by the desert ranges and plateau-like valleys of the Pei-shan. In the south extends the eastern portion of the lower Su-lo-ho valley and the adjoining depression of Hua-hai-tzu. The former is flanked on the south by the outermost hill chains of the Nan-shan and the latter by the end of a hill-range continuing north-westwards of Su-chou.
This southern zone was surveyed from different routes of both the second and third journeys. The plane-table work in this sheet is adjusted for the routes in the southern zone on the positions accepted for An-hsi and Su-chou (Sheets Nos. 38, 43), and for the route in the northern zone on those of the latter place and Barkul (Sheet No. 34). Observed latitudes available for six points are recorded below.
The ground shown in the south-western corner of the sheet was explored by me in the summer of 1907 for the sake of the ruined sites near Ch'iao-tzu and Wan-fo-hsia (A. 5 ) and is described in Desert Cathay, ii. pp. 242 sqq. The historical topography of the ground along the • ancient highroad leading from Su-chou past the oasis of Yü-
26 See above pp. 45, 74.
mên-hsien to An-hsi (Kua-chou) and Tunhuang is discussed in Serindia, iii. pp. 1099 sq., 1136 sqq.
That the ancient Chinese Limes, meant for the protection of this great line of communication, crossed the Su-lo-ho at the extremity of the Wang-shan-tzu ridge (A. 4) and thence lay along the right bank of the river as far as Shih-êrh-tun, near its southerly sharp bend (C. 5), was ascertained by me-already on my rapid passage of 1907. But the Limes line along the right bank of the river and its continuation further east into the Hua-hai-tzu basin was surveyed only in 1914 ; cf. Geograph. Journal, 1916, xlviii. pp,
194 sq. For brief notes on the desert
journey of 1914 across the Pei-shan, see loc. cit. p. 200.
The wholly unsurveyed area of the Pei-shan, traversed and mapped on this journey from Mao-mei (Sheet No. 42. D. 4) to the. easternmost end of the Tien-shan, proved to. conform closely in character to that further west, crossed by the An-shi—Hâmi 'highroad' and briefly referred to in the Notes on Sheet No. 38. The detailed description of our route to be recorded hereafter will furnish support for this statement. Here it must suffice to point out that the succession of much-decayed and utterly barren 'ranges, striking generally from east to west, shown on our map from the north of Ming-shui