PHYSIOGRAPHY OF NORTHWESTERN CHINA. 229 
without drainage, as is the case with the valley northeast of Si-ta-yang, 
or with the Ning-shan valley between the forks of the Hang-ho and the 
Sha-ho. The relations of elevation and depression in consequence of 
tilt during the stage n+ 2 have been such as to cause the removal of 
the Huang-t’u formation over a part of the area of the mountain range 
between Si-ta-yang and Ning-shan, and to lead to the deeper burial of 
the region southeast of Si-ta-yang. 
Referring now to the headwaters of the Hang-ho, we again have 
an example of stream development transverse to the structure, and one 
of rather striking character, since the two branches of the Hang-ho head 
in the district of bad lands, on soft gneiss, and flow directly into a range 
of limestone hills, 1,500 feet, 450 meters, higher than their channels. It 
is possible to extend the explanation, which seems adequate for the lower 
course of the Hang-ho, to these headwater streams, and such an explana- 
tion may suffice. These streams and the parallel course of the Sha-ho 
may, however, have an earlier origin, determined by the normal fault. 
In consequence of that fault, the area of the basin on the downthrown 
side sank lower than the area of gneiss on the upthrown side, and con- 
sequent streams originating on the fault-scarp must have developed with 
courses at right angles to the fault and with a valley from northwest to 
southeast. Such streams may have been the ancestors of the Hang-ho 
and Sha-ho. In that case they probably joined the river which occupied 
the Ning-shan basin and flowed southwestward with it, their diversion 
to the present course toward the southeast being a matter of later devel- 
opment, as has already been discussed. 
The Sha-ho below Féu-p’ing-hién.* —The valley of the Sha-ho below 
Féu-p’ing-hién presents no striking physiographic features. It is aggraded 
with sand and gravel to a width of from half a mile to a mile, and 
bounded by steep rock bluffs. These latter sometimes rise 100 to 200 
feet boldly from the river bank, and occasionally form an obstacle to 
traffic, as in the case at a point 2 miles, 3 kilometers, below Wang- 
k’uai-ch6n, where the path is forced over a dangerously steep ridge by 
the convergence of the river against the base of a cliff. The elevation 
of the channel above sea is 500 feet, 150 meters, near Wang-k’uai-ch6én 
and 800 feet, 240 meters, 24 miles, 38 kilometers, upstream, near Féu- 
p’ing-hién. At the summits of the neighboring hills, the outlook is over 
the area of bad lands, which at once suggests a wide valley level developed 
to old age, with complete adjustment to the distribution of hard and 
soft rocks. This may be regarded as the valley of a large stream which 
occupied the belt between the Ning-shan basin and Féu-p’ing-hién, and, 

* Atlas sheet E I. 
