430 Reviews — Baron RicMhofen^s China. 



begins with tbe upheaval of the whole district after the deposition 

 of strata of the Eothliegende epoch, and continues to the present 

 time. 



The oldest and basement series of rocks are beds of ancient gneiss 

 and granitic gneiss, which have a very wide and general develop- 

 ment, and are characterized by a steep dip and a prevailing strike 

 of N. 30 W. On the denuded and abraded surface of this Ur gneiss 

 there occur beds of newer gneiss, also of hornblendic and chloritic 

 gneiss, varying in petrological characters, and in the direction of 

 the strike to the older beds. These rocks in some districts form 

 elevated and rugged mountainous areas. These gneissoid strata, both 

 older and younger, are regarded by the author as the equivalents of 

 the Laurentian system of other continents, and may be distinguished 

 also from the newer metamorphic rocks by the absence of beds of 

 crystalline limestone. Eesting unconformably on the gneiss is a 

 series of beds of great thickness, and of very varying petrological 

 characters in different localities, but which appear to be of the same 

 relative age. These strata consist of mica-schist, hornblende-schist, 

 quartzite, sandstone, coarse conglomerate green schists, and cr^'stal- 

 line limestones. In one district this series has an estimated thick- 

 ness of at least 10,000 feet, and the author parallels the series with 

 the Huron ian system of other countries. At the close of the 

 deposition of this group of beds a mighty revolution occurred, in 

 which they were highly plicated and faulted, and in some places 

 penetrated by eruptive rocks. The author states that the rocks of 

 this first main period were uplifted to form the skeletons of mountain 

 ranges, and their surfaces experienced enormous and long-continued 

 denudation before the commencement of the deposition of the lowest 

 beds of the second main period. 



The next succeeding group of rocks form the Sinisian system ; it 

 has an extremely wide development, and is readily recognized by 

 similar petrographical characters in areas far apart from each other. 

 The group consists of three series : the lower, a reddish sandstone 

 with local developments of quartz breccia ; the middle, of siliceous 

 limestones with beds of red clay-shale and sandstone ; and an upper 

 series of globulitic limestone, in which the earliest fossils, consisting 

 of fragmentary Brachiopods and Trilobites, are met with. The 

 detailed description of these and other fossils is reserved for another 

 volume, but Professor Dames states that the trilobitic fauna of these 

 limestones chiefly consists of examples of the genera Dikelocephahis 

 and Conocephalus, and bears a closer resemblance to those occurring 

 in the Potsdam sandstones of North America than to those of the 

 Swedish Cambrian strata. The concordant series of beds of the 

 Sinisian system vary in estimated thickness from 12,000 to 20,000 

 feet. The higher portions of the series are placed by the author as 

 equivalents of the Cambrian system. 



Over the greater part of Northern China an elevation of the 

 surface appears to have taken place at the close of the Sinisian or 

 Cambrian period, no representatives of Silurian or Devonian strata 

 appear to be present, and the Sinisian beds are immediately sue- 



