332 RESEARCH IN CHINA. 
and saw the main divide rising like a castellated-wall of limestone before 
us (Plate X). Our elevation was about 3,400 feet, 1,050 meters, and that 
of the summit 7,000 to 8,000 feet, 2,100 to 2,400 meters. The crest was 
but 3 miles, 5 kilometers, away and the nearly vertical limestone strata 
formed sheer mural precipices. The approach to the pass was through a 
remarkable gorge south of Wa-tzi-p’ing. The open valley in the soft 
shales narrows to a slit between the limestone precipices, which are but 
6 to 10 feet, 2 to 3 meters, apart for a distance of a hundred meters (Plate 
XLVII). Then the mountain gorge widens slightly and the trail ascends 
over benches and around cliffs, a thousand feet to the pass. The view 
eastward from the summit is up a broad valley (Fig. A, Plate XLVIII) 
very unlike the profound gorge from which we have climbed, and the 
dip plane of the limestone forms the bold southern slope of the main 
range. But the stream, still taking its course to the Nan-kiang, flows 
directly into the limestone mountains, through a gate still narrower than 
that lower one through which we ascended, and cascades down to Wa-tzi- 
ping. ‘The trail, having passed the point at which the three provinces of 
Ssi-ch’uan, Shen-si, and Hu-pei corner, follows a level ridge for half a mile 
toward the southwest, and then descends the steep slope of the watershed 
of the Yang-tzi-kiang. A study of the old valley profiles shows that the 
headwaters formerly followed a well-adjusted course along the belt of soft 
shales, and flowed to the Yang-tzi. This former course of the stream is 
represented by a col having an elevation of 5,200 feet, 1,585 meters, above 
sea and 600 feet, 180 meters, above the present valley. Itis evident that the 
original stream was retarded by warping and, being reached by an energetic 
branch of the Nan-kiang, was diverted to the northward course in spite 
of the fact that the local conditions were unfavorable to diversion. The 
attacking rivulet had to cross a limestone ridge at least a mile broad, and 
the stream which was attacked possessed a sufficient watershed to give it 
great advantage in volume. Furthermore, it was flowing upon soft shales 
which had formerly determined the adjustment of its course. That, under 
these conditions, the diversion should nevertheless have been accomplished 
is evidence that the northward declivity resulting from warping was very 
considerable. 
Watershed of the Yang-tzi-kiang.—From the Ki-sin-ling pass at an 
altitude of 5,500 feet, 1,675 meters, we descended in 4.5 miles, 7 kilometers, 
to the Ta-ning-ho, only 1,600 feet, 480 meters, above sea, the path follow- 
ing a little lateral stream, which at its lower end leaps 1,200 feet, 360 
meters, in a very short distance (Plate XLIX). The point which we thus 
reached on the Ta-ning-ho is Tung-kuan-k’ou, and the fall of the river in a 
course of about 70 miles, 110 kilometers, to Wu-shan-hién is approximately 
