210 RESEARCH IN CHINA. 
the utterly bleak and barren character of these denuded mountain crests, 
8,000 to 10,000 feet, 2,400 to 3,000 meters, above sea. 
Northwest of the summit of Wu-t’ai-shan and 30 miles, 50 kilometers, 
distant is the valley of the Hu-t’o-ho, which at Tai-chéu has an altitude of 
about 2,000 feet, 850 meters. The O-shui-ho and other streams, which flow 
from the range toward the northwest, thus descend, approximately, 6,000 
feet, 1,800 meters, in 30 miles, 50 kilometers, and lie in very deep, steep 
canyons. In similar rocks the gorges are much more precipitous than those 
of the Ts’ing-shui-ho and upper T’ai-shan-ho, as we might naturally expect 
them to be from the very much greater fall of the streams. Near Yen-t’ou 
the Sinian limestones overlie the Wu-t’ai schists, forming cliffs of very 
striking character; and it is this northwestern canyon which justifies von 
Richthofen’s description of wild scenery and dangerous paths. 
If we consider the relations of the O-shui-ho and the Sha-ho to the 
mountain mass between their head-waters, we see that the latter lies like 
a broad ridge between them, subject to their successful attack. Having 
relatively great fall and especially steep head-gorges, the O-shui-ho and 
Sha-ho are energetically pushing in the divides and so reducing the 
drainage area of the intermediate streams. 
In the course of our wanderings in the Wu-t’ai-shan we crossed several 
of the passes at altitudes of 7,000 or 8,000 feet, 2,100 or 2,400 meters, and 
visited or viewed the high summits from various sides. They everywhere 
present the broad low forms illustrated in Plates XXXII and XXXIII, 
forms of a surface of denudation under conditions of altitude quite different 
from those which now permit the autogenous tributaries of neighboring 
streams to attack them vigorously. This mountain type is common 
throughout southern Siberia, as may be seen in the illustrations of various 
travels across Asia. One finds it, for instance, in the views of the moun- 
tains along the upper Huang-ho,* and it is common in the descriptions of 
the northern Altai and the Urals. These broad highlands of the Wu-t’ai- 
shan are believed to represent an early stage of topographic development 
at a relatively low level, and to be the oldest topographic forms which we 
saw in the course of our journey. 
Northern Loess Basins.t—Coming from Yen-t’ou up the wild canyon 
of the O-shui-ho, I recrossed the Wu-t’ai-shan south of Ts’a-pu; my com- 
rades, coming from the upper T’ai-shan-ho, crossed the pass between 
Nan-t’ai and Si-t’ai; and our routes converged at Li-yiian-p’u. Our view 
southwestward was over a widening expanse of low hill country. A broad 
valley bottom lay below at a general elevation of 4,000 feet, 1,200 meters, 
and from it rose many hills only 1,000 to 1,500 feet, 300 to 450 meters, 

*Durch Asien, Dr. K. Futterer, vol. 1, Plate 28. 
t Atlas sheets CI, BI, CII, and B II. 
