SINO-MONGOLIAN FRONTIER 



The slopes facing the plain (i.e. eastward) are 

 in the form of a steep and rugged escarpment, 

 formed, possibly, by extensive erosions, but more 

 probably by a fault running roughly north and 

 south, with the downthrow on the east. This 

 theory may be supported by the fact that the 

 strata, which are very marked, dip to the west at 

 varying angles. Slight folding is also noticeable. 



After passing westward through the Hu-t'o 

 series for a short distance, one encounters typical 

 Sinian limestones, which are next replaced by 

 sandstones of the Shansi coal measures. Here, 

 at a point just before Ching-hsing Hsien is reached, 

 a good quality of bituminous coal is extensively 

 mined by the Ching Hsing Mining Company. 



Immediately west of Ching-hsing Hsien, mas- 

 sive limestone mountains are again encountered, 

 suggesting the existence of another fault, especially 

 as the eastern slopes again present rugged escarp- 

 ments, and the strata still dip to the west. As far 

 as could be judged from the train, this limestone 

 extends all the way to the P'ing-ting Chou district. 

 This does not agree exactly with Richthofen's 

 map, which gives alternating outcrops of limestone 

 and coal measures, but it must be remembered 

 that the railway line follows the valley bottoms, 



it was described and named " Untersinisch " by Richthofen. 

 This was subsequently divided from the Sinian system by 

 the members of the Carnegie Expedition, 1904, who discovered 

 the unconformity between the two systems. 



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