PHYSIOGRAPHY OF NORTHWESTERN CHINA. 235 
distinguish it from ordinary rivers, and especially from other rivers of 
equal magnitude. 
The middle Huang-ho has no considerable valley. If we attempt to 
follow it from its delta on the great plain of eastern China, we have, indeed, 
a channel which marks a continuous river, but we have not a valley of 
erosion which we may attribute to the stream. As we saw it at the Tung- 
kuan, and as it is described in its course from that point eastward, it is 
a stream occupying a depression produced by normal faulting. It has 
taken possession of a channel, but has not made one. In its long course 
from north to south, above the great elbow between the provinces of 
Shan-si and Shen-si, it flows much of the way in a canyon, and where 
not bounded by cliffs of rock it is shut in by walls of loess. Some por- 
tions of its channel appear to be antecedent to upwarps in the surface, 
and we are thus thrown back to an earlier date than that of the warping 
for the beginning of the river’s course. But it appears from descriptions 
given of the valley in works of travel or by the natives, that nowhere 
in its lower section is the river accompanied by that wide channel of an 
older valley which we would expect if it had long flowed in its course 
across the surface. On making inquiries at T’ai-ytian-fu and Fon-chéu- 
fu, regarding the possibility of a journey along the river’s banks, we were 
told that such a trip would hardly be possible. The steep bluffs against 
which the river impinges, and the many gullies extending down to the 
stream, would make it difficult for a pack train to pass, while on the other 
hand, the many shallows and rapids in the current make it dangerous 
for boats. In seasons of high water the river is navigated by boats, which 
carry coal downstream to Si-an-fu, but no boat is ever taken upstream. 
Thus it seems that the only practicable opportunity to make a recon- 
naissance of the river is the rather unsatisfactory one of running it in 
flood time. 
These characteristics of the river valley point to unusual youth, and 
apparently indicate an absence of an earlier history. Without being able 
to speak from full observation, we are thus led to infer that the Huang-ho 
is a youthful stream, and we may propose as a working hypothesis the 
following theory of its development. Let it be assumed that the Huang- 
t’u formation was spread upon a relatively mature surface of erosion, 
and that its accumulation formed an extensive plain of aggradation, 
in which the old topography was, to a considerable extent, buried. Let 
it be assumed, furthermore, that this surface was tilted, so that the 
northwestern portion lay higher and the southeastern portion lower; 
that is, that it was depressed toward the downthrow of the great normal 
fault-blocks of Shan-si and Shen-si. Prior to the tilting there may have 
