PHYSIOGRAPHY OF SOUTHERN SHEN-SI. 323 
rocks; in that case they too are narrow, scarcely passable canyons, as 
between Siau-wang-kién and Chang-k’6u-shi; but 2 to 3 miles, 3 to 5 kilo- 
meters, south and southeast of Lung-t’an-ssi and about Mu-tzi-p’ing the 
valleys eroded in slate are comparatively open, though nowhere so widened 
as to leave space for an acre of bottom-land. There is no doubt but that 
softer rocks influence the grading of gentler slopes, but it is also possible 
that the wider valleys represent a stage of corrasion antedating that of 
the lower canyons, which have in that case not yet cut back into them 
(Fig. A, Plate XL). Thus the open valleys above 4,500 feet, 1,375 meters, 
southeast of Lung-t’an-ssi, may correspond to the terrace at 3,400 feet, 
1,035 meters, near Ir-ling-p’u, if the valley at that time had a fall of 
about 70 feet, 20 meters, to the kilometer; or to the terrace at 4,500 feet, 
1,375 meters, provided the northern front of the range has been raised 
somewhat higher in later faulting than the district about Lung-t’an-ssi. 
It is possible to find among the valleys and terraces relations which cor- 
respond very nicely, but the cases are not sufficiently numerous to support 
an inference as to the movement of the mountain block, whether one of 
uniform uplift, of warping, or of rotation. 
When we ascend above Ir-ling-p’u or Lung-t’an-ssi to about 6,000 
feet above sea, we find a wide ancient valley expanded between narrow- 
crested ridges and pyramidal hills (Fig. A, Plate XLI). Surviving spurs 
are numerous but narrow, and they slope from 6,500 to 5,500 feet, 1,975 
to 1,675 meters; near the upper limit they pass into the steeper hillside; 
near the lower they end at the abrupt canyon edge. The surface is covered 
with residual soil, now deeply gullied in consequence of destruction of 
the forest for lumber during the last thirty years. 
The valley high above a river is a general feature of the Ts’in-ling-shan, 
as may be seen from a broad view sketched from a commanding peak 
southwest of Siau-wang-kién (Plate XLII). It is there indicated by the 
profiles marked b, which are traceable even in the great and distant heights 
of the Ta-pai-shan. It is a topographic condition closely resembling that 
which was seen in the Wu-t’ai-shan and marked 6 on Plate XXX, and 
it is interpreted as corresponding with that in representing a mature stage 
of topography. In northern China we know it as the T’ang-hién stage of 
degradation, followed by the Hin-chdéu stage of aggradation; but in central 
China we can not recognize these by their characteristic relations, and it is 
best to distinguish the mature stage in the southern region by a separate 
name. It is well represented in the ancient high valleys of the Ta-pai-shan 
and T's’in-ling-shan, and we call it the Ts’in-ling stage. The character 
of relief appropriate to its stage of development may be seen in the higher 
profiles of the sketches and photographs (Plates XLI and XLII); or may 
