PHYSIOGRAPHY OF SOUTHERN SHEN-SI. ao% 
fields, and hillsides on which grow large and handsome trees, ever closing 
in the vista of the winding stream (Fig. B, Plate III). 
Between Pa-kua-miau and Pai-kiu-hia (atlas sheets c5 and d5) we 
crossed two divides, the northern 4 miles, 6.5 kilometers, southeast of Pa- 
kua-miau at an altitude of 5,000 feet, 1,500 meters, and the southern at 
Hung-kia-ying at 4,100 feet, 1,230 meters, above sea. Though we had thus 
reached an altitude of 4,000 feet, 1,200 meters, above the Han river at 
Hing-an-fu we were still within its watershed, and descended to the canyon 
of the Nan-kiang, whose course is first easterly and then northeasterly 
past Chii-shan-hién to a junction with the Han above Yiin-yang-fu. 
Up the Nan-kiang.—In distant views which we had of the valley of 
the Nan-kiang, we observed the elements of topography which we had 
recognized elsewhere in the region, but they are developed on a grander 
scale. The Nan-kiang flows in a narrow and often impressive canyon, 
between cliffs which are frequently 500 feet, 150 meters, in height, and 
which descend abruptly into the river, forcing the trail to cross, or where 
that is not practicable, obliging the natives to cut the pathway in rock. 
At several points such work has been done to make the route practicable. 
Two miles, 3 kilometers, north of Ku-niu-tu (atlas sheet d 6) there is 
an interesting occurrence of a stream which enters the main river from 
the west in the middle of the concave side of an ox-bow, between two 
high sharp-crested ridges. The peculiar relations of the tributary and the 
bend suggest that the ox-bow was caused by the alluvial cone of the small 
stream, at a time when the valley was 300 feet, 90 meters, above the present 
channel, and that the tributary now pursues the course which it took on 
its alluvial cone. The feature is significant of a gentler fall of the main 
river than that which it now has, for at the present time its powerful 
current sweeps away the gravel contributed to it, even by much larger 
streams than the little brook that now enters the ox-bow. This old valley 
level of the Nan-kiang, clearly developed 300 to 500 feet, 90 to 150 meters, 
above the river (Plate XLVI), has a relation to the inner canyon parallel 
with that of the elevated valleys we saw south of Hing-an-fu about 120 feet, 
36 meters, above the streams in that region. The canyon of the Nan-kiang 
is cut deeper, because the stream is higher above its level of discharge and 
is a far more powerful river. It is still cutting vertically, its channel being 
high above a graded profile. 
As the canyon became deeper and walled us in more closely (Plate 
IX), we saw less and less of the nearby heights, yet we were conscious, from 
glimpses of distant peaks, that we were entering among much higher 
mountains than those we had traversed. Four miles south of Chén-p’ing- 
hién we emerged into an east-west valley developed on a zone of soft shales, 
