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SCIENCE 



[N. S. Vol. XXIX. No. 737 



to the Tang-tzi-kiang. In so far as the sur- 

 vey was necessarily rapid it partook of the 

 nature of a reconnaissance and was restricted 

 to type areas and to limited widths of terri- 

 tory, but it was of a character greatly su- 

 perior to most reconnaissances in that the 

 topography and geology within these limits 

 were accurately mapped and comprehensively 

 studied. Puture work, therefore, needs simply 

 to extend what has been already so well begun. 



A brief summary is not included in the 

 publication and a review may, in passing, 

 mention the prominent features of the geologic 

 liistory as set forth in the second volume. The 

 -Archean is restricted by the author to the 

 snetamorphic schists and gneisses of indeter- 

 minate character associated with a large pro- 

 portion of metamorphosed igneous rocks, 

 which by their intricate structure and inferior 

 position to the oldest pre-Cambrian recog- 

 nizable sediments are marked as belonging to 

 a distinct and older system. The overlying 

 Proterozoic was chiefly studied in the Wu- 

 Tai-Shan and is divided into two systems, the 

 eo- and neo-Proterozoic, the local Chinese 

 names being omitted in this review. The 

 eo-Proterozoic embraces three series separated 

 by two unconformities. 



Von Richthofen placed this system in the 

 Huronian, using the latter term, as was com- 

 monly done thirty years ago, to suggest pre- 

 Paleozoio rocks of green color. He did so with 

 reserve, however, and the stricter usage of the 

 term as it is now adopted does not permit us to 

 maintain an exact correlation. 



Willis points out, however, the strong sim- 

 ilarities of these three series to the three 

 Huronian series of the Lake Superior region 

 and Van Hise has more recently compared 

 them with still other formations of other 

 regions similar in lithologic character and 

 age relations. As Willis states: 



The general relations to the Archean and neo- 

 Proterozoic are similar in both continents, and 

 the effects may well have been due to a general 

 terrestrial cause which became active at about the 

 same time, in regions remote from one another. 



Between the eo- and neo-Proterozoic occurs 

 a. stratigraphic break of the first order, indi- 

 cated both by a great unconformity and by 



the folding and metamorphism of the lower 

 system which are absent from the upper. The 

 little altered, slightly slaty beds of the neo- 

 Proterozoic resemble the Paleozoic above far 

 more than the eo-Proterozoic below. At least 

 10,000 feet of slates, limestones and quartzites 

 are embraced in this system. After a period 

 of diastrophism the wide-spread land surface 

 was reduced to a nearly perfect plain over 

 which finally passed in places the Cambro- 

 Ordovieian sea. This pre-Paleozoic pene- 

 planation was observed over a stretch of a 

 thousand miles and is a feature of southeast- 

 em Asia. 



The fact that Asia at the opening of the Pale- 

 ozoic era was a featureless continent has impor- 

 tant bearings. It limits the antiquity of moun- 

 tain ranges, some of which have been discussed 

 by eminent writers as of pre-Cambrian date, as 

 elevations which have survived since that remote 

 time; and it affords a basis of inference regarding 

 a cycle of inactivity, which was common to other 

 continents as well. 



The marine invasion which initiated the 

 Paleozoic sedimentation began in the late 

 Lower Cambrian and gave rise to the Sinian 

 group, extending to the Middle Ordovician. 

 In central China the Sinian is composed of 

 limestone, apparently to its very base, but in 

 north China the characteristic strata of the 

 Lower Sinian are red deposits. In south 

 China, latitude 31° north, near the base of 

 the Sinian and conformably interbedded be- 

 tween a quartzite below and marine limestone 

 above occurs the bed of tillite which has at- 

 tracted so much attention on account of the 

 profound significance of this early glaciation 

 near the level of the sea. 



The Lower Ordovician strata are overlain 

 by Upper Carboniferous, but without discord- 

 ance of dip, implying prolonged quiet with 

 most of the continental surface lying near 

 sea level. The Carboniferous is characterized 

 by marine deposits in the south, by continental 

 deposits in the north. The transition to the 

 Mesozoic is not marked by a sharp division 

 plane, but by shrinkage of the seas and an 

 increase in the proportion of continental de- 

 posits. At the same time Permo-Mesozoic 

 diastrophism was pronounced and the present 



