PHYSIOGRAPHY OF SOUTHERN SHEN-SI. 495 
forbidding canyons of the northern slope and the chill climate of lingering 
winter for sunny valleys and the aspects of spring. 
Southern slope of the Ts’in-ling-shan.—Descending to Ning-k’ou-ssi, 
we passed waterfalls over granite ledges, and there found a very narrow 
glen within a stretch of sloping fields strewn with big angular rocks. For 
some reason, probably a line of close jointing, the gorge is narrowed for 
200 meters and sunk a hundred feet in the previous valley floor, which is 
not so well preserved below the glen. Between Ning-k’ou-ssi and Ts’ai- 
kia-kuan our route lay by small brooks tributary to the P’u-ho, which 
show processes of recent adjustment to the belts of softer schists. We 
soon left the stream that flows by Ning-k’ou-ssi and entered a back valley, 
in which we crossed two low divides, separating little watersheds that 
discharged westward between hills of harder rock. In the province of 
the Han valley such adjustments are more conspicuous than in any other 
district through which we passed. The rock mosaic is generally composed 
of schists, which are weak, not only because of their mechanical fissility, 
but also because they are deeply decayed, whereas certain quartzites, 
limestones, and homogeneous granite masses are relatively hard. The 
mosaic has long been exposed to erosion, and the streams have had oppor- 
tunity to reach adjustment and have to a considerable extent done so; 
yet in consequence of having recently sunk their channels, in some cases 
hundreds of feet, they have become superimposed upon newly discovered 
hard ledges and have developed new opportunities for readjustment along 
weaker zones. ‘Thus their valleys present alternations of canyons and 
open stretches; yet nowhere may we look for wide bottom lands, for 
there has not been time for their development. 
Approaching the P’u-ho above Ts’ai-kia-kuan at an elevation of 3,500 
feet, 1,050 meters, we came upon the highest rice-fields, established on a 
broad alluvial cone; and thence southward to Shi-ts’iian-hién our way 
lay through a district in which small farms are numerous, both in the 
little strips of alluvium beside the river and on the spurs of the mountain 
slopes. The benches on the hillsides occur in continuity of relations such 
as to show that they are not accidents of relief due to hard rocks, but 
represent former levels at which the valley floor was temporarily developed 
during the process of sinking the channel. We see these benches in Plate 
XLIII, at no great height above the stream, and may observe that others 
are faintly recorded in higher slopes, but we are not able to reconstruct 
the details of history from our meager observations. At San-ho-k’ou and 
near Liang-ho there are well-developed ox-bows, which are incised 300 feet, 
90 meters, below the level of the valley, in which they probably originated 
and which afford some measure of the latest sinking of the valley. 
