ANTIQUITY OF MOUNTAIN SITES. 27 



Regarding the great Kuen-lung system of Central Asia, the available 

 data clearly distinguish highly metamorphosed sediments beneath Devonian 

 or pre-Devonian strata. They appear to fall into two groups, of which one 

 consists of schists like the Wu-t'ai schists, rocks of the other group being 

 less altered ; and the facts indicate a sequence of activities which resemble 

 those of Wu-t'ai time. 



Thus in an arc which extends from the Wu-t'ai-shan in Shan-si around 

 the southeastern and southern margins of the Mongolian plateau, there 

 may be traced evidence of a very ancient mountain movement or group of 

 movements. The axial trends of the early structures correspond in a 

 degree, though not exactly, with the existing ranges, and this coincidence 

 forms a reasonable basis for the view that certain conditions, possibly 

 mechanical, have controlled and still control the courses of mountain 

 chains. The coincidence does not demonstrate the continued existence 

 of the Wu-t'ai or Kuen-lung ranges as mountainous elevations from early 

 Proterozoic time to the present; in view of the stratigraphic evidence that 

 Sinian lands were low, or of the physiographic evidence that the present 

 mountains have grown up largely since the Tertiary, such a hypothesis is 

 untenable. Nevertheless, it is one which was commonly accepted thirty 

 or forty years ago. Von Richthofen regarded the Kuen-lung line as a great 

 divide established in a very early period,* and describes the Ho-shanf as 

 a monument of the oldest time, which formed a long island in the Carbonif- 

 erous sea. King's views of the antiquity of mountain heights of the United 

 States are clearly expressed in the volume on the systematic geology of 

 the Fortieth Parallel. The effectiveness of erosion and the significance of 

 strata as records of highland or lowland conditions have since received 

 more adequate recognition. Beginning with Powell's conception of a base- 

 level and the demonstration that the Appalachian folds had been planed, J 

 the generalization has been developed that existing heights are nearly all 

 post-Cretaceous and largely post-Miocene. But at the same time the view 

 has been strengthened that zones of mountain growth are so conditioned 

 that repeated elevations occur on the same sites with similar trends, though 

 at widely separated intervals. In the latter sense the Wu-t'ai and Kuen- 

 lung axes of mountain growth are very ancient, one may say primeval, 

 features of Asia. 



Traces of the mid-Proterozoic epoch of orogeny are found in Liau-tung 

 and Shan-tung, the eastern mountain provinces, in meager occurrences of 

 pre-Sinian sediments, which are so metamorphosed as to be compared to the 



* China, vol. u, pp. 647-648 and 709. 



1 Ibid., p. 457. 



|W. M. Davis, Rivers and Valleys of Pennsylvania, Nat. Geog. Mag., vol. I, p. 183, 1889. 



