PHYSIOGRAPHY OF NORTHWESTERN CHINA. 209 
given in Plate XX XI, taken 4 miles, 6.5 kilometers, south of the first, 
one view being south, the other north of west. The summits which are 
marked a rise above the long level spurs, marked b, and are connected 
with them by many accidents of slope and shoulder. Hidden behind the 
ridges are the canyons, to which the line c directs attention. The view is 
one of a surface which has a complex history of uplift and erosion, a history 
expressed in the relations of the several features; but it is necessary to 
penetrate further before attempting to unravel their sequence. 
From the Chi-li-Shan-si divide we descended into the canyon of the 
Ts’ing-shui-ho, which, in this district of Pre-Cambrian schists, is bounded 
by slopes of relatively moderate inclination. The Ts’ing-shui-ho joins the 
T’ai-shan-ho, and the two flow southward in a channel which grows 
wider until, entering the mountains of Sinian limestone, it becomes a 
narrow, steeply walled gorge. The bottom of the canyon is filled with 
the coarsest shingle, and the streams meander in ever-changing channels 
from side to side. Our route turns up the T’ai-shan-ho and follows that 
stream to the village of Wu-t’ai-shan, the road being a mere track over 
coarse gravel (Plate IV). An alluvial cone of great size lies at the mouth 
of each tributary gulch, evidence of the rapid and vigorous denudation 
of the mountains. These cones appear to be young, the material having 
accumulated from the little streams, but not yet having been carried far 
by the larger T’ai-shan-ho, and the reason for their recent development 
is found in the fact that the forest has been removed from the mountains 
in the last two hundred years. Before that time the region had been 
occupied only by the priests living in monasteries, which, to the number 
of seventy, are built at Wu-t’ai-shan and elsewhere among the mountain 
recesses; but within two hundred years the Emperor Kang-hi promoted 
immigration into the mountains and allowed the people to cut the timber. 
The complete destruction of the forests has been accomplished in that 
brief time and the denudation of the mountains is proceeding at a very 
rapid rate. 
The gorge of the Tai-shan-ho, like that of the Ts’ing-shui-ho, is cut 
in the Pre-Cambrian schists and in general presents sides of moderate 
slope, but here and there, where it crosses quartzites or conglomerates, 
the walls rise boldly several hundred feet. In its upper reach, near Wu- 
t’ai-shan, the valley, in chlorite schist, widens and branches extensively, 
and the slopes of the main Wu-t’ai range, including the summits of Tung- 
t’ai, Pei-t’ai, Chung-t’ai, and Si-t’ai, are broad and smooth. The general 
character is illustrated in the panoramic view from Nan-t’ai toward the 
northeast and north (see atlas sheet E I) and in Fig. B, Plate XXXII, 
which extends that view westerly. It would be difficult to exaggerate 
