PHYSIOGRAPHY OF NORTHWESTERN CHINA. Pasi 
high. On our right the principal range of the Wu-t’ai rose imposingly 
against the western sky, but in the remote distance, west by south, it sank 
away to the inconspicuous ridge at Hin-k’ou. On our left the southern 
spurs of Nan-t’ai reached as a high range toward the Chi-li-Shan-si divide, 
with which they form the western end of the Ki-chéu-shan, the highland 
through which the T’ai-shan-ho winds its deeply sunken channel. The 
lowland between the ranges was like a deep bay, at the head of which we 
stood, and which widened beyond our vision. It was the embayment of 
the northern Loess Basins.* 
The descent from the leveled pass of the Wu-t’ai-shan to Li-ytian-p’u 
was very steep for 1,500 feet, 450 meters, and on rock; below the rock- 
scarp the ravine was filled with a steep alluvial cone, and it was clear that 
the intermittent brook was gathering more detritus from above than it 
could handle below. 
When we had descended to the valley, the general view was lost and 
local details became important. The Huang-t’u formation of loess and 
gravel overspreads the valley floors. Where torrents run in the rainy 
season they cut channels, whose vertical walls are of loess while their beds 
are of coarse shingle (Fig. A, Plate XXV). Elsewhere the waters spread 
in extraordinarily wide floods, and the precious loess soil which they carry 
is caught in inclosures of stone walls (see panoramic view, atlas sheet 
A Ill). The Huang-t’u curves up and onto the mountain spurs with a 
characteristic tangent profile, but is cut away in the ravines. Tattered 
remnants of it cling here and there in strange situations, and challenge 
alike the advocate of wind or of water as the agent of loess distribution, 
for neither may account readily for what he finds. 
The valley which we entered at Liu-ytian is triangular, having one 
acute angle at the northeast, where it branches in autogenous fashion; 
a second angle at the western pass, Ts’ai-shi-ling, where the low divide is 
covered with Huang-t’u, and the third at the southeast, where the Shi- 
t’ou-ho enters the canyon that leads to the T’ai-shan-ho. This triangular 
valley is the northeastern loess basin, the Shi-t’6u-ho or Téu-ts’un basin. 
Before leaving it we must note the occurrence of the Huang-t’u in the high 
valley east of Liu-yiian, 1,200 to 1,500 feet, 375 to 450 meters, above 
the basin. ‘This valley lies behind a low range of hills and is reached bya 
deeply cut canyon, which has diverted its drainage from the original south- 
easterly course (see the common margins of atlas sheets C I and D I). 
From Téu-ts’un to Wu-t’ai-hién the way lies across the second loess 
basin, a double valley without outlet. The hills between the two depres- 
sions are buried in the Huang-t’u, which floors the lowland. Sections of 

* This region is well described by von Richthofen in China, vol. 11, pp. 369, 370. 
