372 J. S. Lee—An Outline of Chinese Geology. 
mountains. The intense folding that prevails in all parts of these 
ranges is certainly an excellent condition for the preservation of 
extensive strata if they were once present ; and the peculiar lithology 
so widely prevalent with Sinian rocks, together with their highly 
fossiliferous nature, would form conspicuous landmarks that could 
not have escaped the notice of so many keen observers if the rocks 
were there. 
From early Cambrian time to the end of the Ordovician period, or 
probably later, there was little alteration of the distribution of 
land and sea in China. The processes of denudation and deposition 
were allowed to continue their operation in a monotonous and un- 
disturbed manner. Hastern Yun-nan is the only area that was in 
a relatively unstable condition. The intercalation of limestones in the 
lower gritty series, the grits in the upper argillaceous strata of the 
Cambrian formation, and the local unconformity between the 
Ordovician and Upper Cambrian are probably all due to the oscilla- 
tion of the sea-floor. Igneous activity is practically unknown in 
China throughout the whole of the Sinian period. 
THE SILURIAN AND DEVONIAN. 
The results of geological researches and mining records hitherto 
obtained in northern China have conclusively shown that in this 
vast area the Sinian System is separated from the overlying Shansian 
coal-bearing rocks by an unconformity of great magnitude. Although 
the contact between the two is generally of concordant nature, the 
hiatus of life sequence proves the existence of an unconformity 
beyond any doubt. The top of the Sinian contains Ordovician 
fossils as already mentioned ; near the base of the overlying Shansian 
System marine fossils have been found. Though the exact age 
indicated by these fossils is still a matter of dispute, they un- 
doubtedly represent the life of a period not earlier than the Lower 
Carboniferous. ; 
From these paleontological data it follows that Silurian and 
Devonian deposits are practically absent in northern China, namely, 
in the provinces of Manchuria, Shan-tung, Chi-li, Shan-si, Ho-nan, 
and probably Shen-si. Either during the whole of these periods 
or a part or parts of them these provinces must have been 
subjected to uniform erosion, consequent to a broad epeirogenic 
movement. 
Lorenz speaks of Upper Devonian transgression ! in Shan-tung on 
account cf the presence of a series of coarse strata having a maximum 
thickness of not more than 300 feet. These rocks lie between the 
eroded Sinian limestone and a fossiliferous zone which is doubtfully 
assigned by Professor Frech to the Lower Carboniferous. In the 
absence of further evidence it would appear risky to accept Lorenz’s 
hypothesis. 
1 Lorenz, “‘ Beitrage z. Geol. u. Pal. von Ostasien, etc.”’: Zeits. d. d. Geol. 
Gesell., vol. lvii, pp. 448-50. 
