166 RESEARCH IN CHINA. 
unconformably upon folded, deeply eroded, and planed-off Paleozoics.* 
Moreover, the Triassic or Jurassic age of the higher strata rests upon the 
evidence of incomplete collections of fossil plants, from a district where the 
evolution of floras during the late Paleozoic and Mesozoic was peculiart 
as compared with Europe and America. It follows from these qualifica- 
tions, that we can not with confidence place the episode of folding in the 
Wu-t’ai district more nearly than to say that it was probably Mesozoic. 
In the chapter on the middle Yang-tzi region we consider the possibility 
of two episodes, the one during the Triassic, the other post-Jurassic. 
TERTIARY MOVEMENTS. 
Warping.—Even although we should extend our search far beyond 
the limits of the area under consideration, we would find no Tertiary 
sediments. There is no evidence of a submergence later than the Paleozoic, 
although there are continental deposits of Jurassic age near Ta-tung-fu. 
As an area of erosion, northwestern China ultimately reached a peneplain 
condition, which characterized the landscape in early or middle Tertiary, 
during what we designate the Pei-t’ai cycle,t and it is evident that the net 
result of the movements following the Mesozoic epoch of folding was per- 
haps a certain amount of warping, ending in quiescence and advanced 
erosion. Early in the Tertiary occurred the normal faulting, which is 
represented in the Ning-shan basin of Chi-li and in Shan-tung. Late in 
Tertiary time there began certain broad movements, which resulted in ele- 
vation and depression, but it was not until the late Pliocene that marked 
deformation took place; and not until the middle of the Pleistocene, as 
we interpret the facts, that the very pronounced features of the mountain 
chains were initiated. Deformation then assumed the form of normal 
faulting. 
QUATERNARY MOVEMENTS. 
Normal faults.—Normal faulting constitutes a feature of the structure 
which is distinct in type and time from all other features. It has no 
relation to the folds of the rocks, which it transects at an acute angle in 
the face of the Ki-chéu-shan, and being an effect of vertical warping is in 
strong contrast to the results of tangential thrust. The folding probably 
ceased in the Mesozoic, but the faulting, begun in this region not earlier 
than the Pleistocene, has continued almost or quite down to the present. 
One great normal fault occurs in the Wu-t’ai district, stretching along 
the base of the Ki-chéu-shan, between the mountain mass and the sunken 
floor of the Hin-chéu basin. It is a feature of the great fault system of 
central Shan-si, and as such is described in the next chapter. 

*Von Richthofen, China, vol. 11, p. 602. 
{White's report on Plants from the K’ui-chéu Series, Chapter XII. 
{See Chapter XI. 
