IIO RESEARCH IN CHINA. 



are disconnected. They have not been observed from the point of view we 

 are now taking. The available data relating to the structural trends, the 

 isolated ridges, the desert plains, and the deep depressions are gathered by 

 Suess into a masterly description in the third volume of Das Antlitz der 

 Erde. The acute features of dislocation and erosion; the warping of the 

 Tertiary Gobi deposits and their occurrence high on the ranges from which 

 they extend to basins below sea-level: these suffice to bring the period 

 of diastrophism to which the relief is due within the later Tertiary and 

 Quaternary. I quote Huntington, who has studied the western part of 

 the vast region.* In regard to the Zorabad basin, he says: 



Apparently it was first occupied by the sea and later became dry land. Then, by 

 the warping of the earth's crust, it was converted into a lake, which in time was drained 

 by the cutting of a gorge. As the water of the lake receded, gravel was washed in from 

 the sides and covered the lake deposits. Since that time the gorge at the outlet has been 

 cut deeper, the various deposits have all been more or less dissected, and terraces have 

 been formed. At intervals during the progress of these events, warping has gone on in 

 such a fashion that the size of the basin has continually diminished and all the deposits 

 except the most recent gravels have been warped along the edges, although apparently 

 remaining horizontal in the center of the basin. Most of this history probably belongs to 

 Tertiary times, although the dissection of the lake deposits and the formation of the terraces 

 almost certainly belong to the present geological era. 



In order to understand the geological history of Persia it will be necessary to ascertain 

 to what extent a similar series of events has occurred in other basins. What few facts 

 are known indicate that the history of all the basins is similar to that of Zorabad, with the 

 exception of the lake episode. The only lakes of which we have record in the other basins 

 occurred at a later time and were due to changes of climate rather than to warping of the 

 crust. 



The mountains of Trans-Baikalia constitute a group which is clearly 

 distinguished from the Gobi region on the south, the plateaus to the north- 

 east, and the plains of the amphitheater of Irkutsk to the northwest. 

 Whereas the Gobi is a region of displacement and aggradation and the 

 plateaus are one of regional uplift and the plains one of regional depression, 

 Trans-Baikalia is characterized by elevation, faulting, and denudation. I 

 have already cited the evidence adduced by Suess for ascribing to the basin 

 of Lake Baikal a late Tertiary date, and stated that the conclusion may be 

 extended to the ranges of Trans-Baikalia. This applies to the principal 

 heights in the northeastern district. It is doubtful how far the Tertiary 

 uplift may be traced in the adjoining plateau district, where the sharply 

 defined canyon of the Lena has the aspect of a Quaternary gorge. I am 

 inclined to regard the Trans-Baikal mountains as an insular faulted upwarp, 

 like Shan-tung, and to infer that the plateau region is of later elevation. 



* Explorations in Turkestan, Carnegie Institution of Washington Publication No. 26, p. 242. 



