THE KHINGAN PLEXURB. 1 07 



ended on the south with a short monoclinal flexure. Were that to be the case in this 

 region the plateau must extend far toward the east; but this did not seem probable, as 

 according to all accounts I was near the end of the anthracite region. In fact I came 

 sooner than I expected to the first fault. The general relation was indeed difficult to under- 

 stand in a single rapid traverse, but it was soon clear that the plateau fell off in steps, 

 which are occasioned by faults along a great fault zone, which runs from north to south 

 and is in part connected with gentle flexures. If one regards the attitude of the strata in 

 individual cases, one often finds it confusing, for locally the limestone dips in various 

 directions and with different angles. This is particularly noticeable in the descent from 

 each separate step. But if one looks back toward the west from a little distance and 

 regards the steep slope of the ridge which has just been crossed, one is surprised to observe 

 in general only horizontal lines of stratification. In every such case one is on that portion 

 of the surface which has sunk down with reference to the higher steps. The variations 

 in the altitude of the strata may possibly be related in part to the displacement of the 

 beds in the tremendous process of faulting, or may in part be due to caving in, there being 

 in some places caverns, which occur especially in the Rauchwackc. 



While these observations are avowedly incomplete and do not carry 

 conviction to the reader, the conclusion is not inconsistent with the warping 

 observed elsewhere. Warping and faulting are related phenomena; the 

 latter is an extreme effect of a concentrated stress set up in consequence 

 of the former, and may be looked for wherever the zone between an area 

 of depression and one of elevation is relatively narrow as compared with the 

 difference of altitude resulting from the movement. 



I conclude that the weight of evidence shows that the passage from 

 the depressed region to the elevated plateaus of the mountainous area is 

 by a warped surface more generally than by a dislocation, and that the 

 ' ' Khingan I,ime " is to be regarded as a zone of monoclinal flexure, not as 

 a fault. 



The depressed region just described is one of the eastern or outer 

 provinces of the continent. While it has subsided somewhat, the region 

 on the northwest has risen considerably more. The physiographic record 

 shows that up to the close of the Hin-chou epoch the difference of altitude 

 between the two was no more than that of a gentle, continuous slope, but 

 since that time it has been increased to 6,000 or 7,000 feet, 1,800 or 2,100 

 meters, on a moderate allowance of 5,000 feet for the elevation of the 

 T'ang-hien surface in the plateaus of Shan-si, and of 1,000 to 2,000 feet, 

 300 to 600 meters, for the depression of the same surface beneath the 

 Great Plain. 



This difference in altitude has developed within the late Pliocene and 

 the Quaternary; probably chiefly during the latter. There are two con- 

 ceptions of the manner: The region which is high may be regarded as a 

 horst, which has stood firm while the adjacent area has sunk down below 



