MIDDLE YANG-TZi'-KIANG GORGES 597 



connection with the rest of my researches, it could not be expected to 

 occur there. Willis continues : 



Between Nan-mu-yiian and Wu-shan-hien the Yang-tzi flows across a sequence 

 of smaller and larger folds, chiefly of the Ki-sin-hng limestone, but, at the head 

 of the gorge, consisting only of the Wu shan limestone. The sequence will best 

 be understood by reference to the section [see his Fig. 61], which was sketched, 

 as we floated past the magnificent cHffs in which it was exposed. As we could 

 not measure distances, the distribution along the river was noted and has since 

 been adjusted to "Chevalier's map of the Yang-tzi." Two anticHnes and a 

 syncline bring the top of the Ki-sin-ling limestone high above the stream, above 

 and below Nan-mu-yiian. For several miles below Ts'ing-shi-tung the course 

 is in the axis of a carinate syncline, a position determined by the Sin-t'an shale, 

 although the canyon is now sunk below that formation in the Ki-sin-ling lime- 

 stone. The thin beds of the latter dip very steeply, but above them, in a nearly 

 flat position, the Wu-shan forms the upper cliffs. From half a mile above 

 Ts'ing-shi-tung the synclinal valley extends westward but it is occupied only by 

 a small tributary. The lower part of the Wu-shan gorge is cut across a great 

 anticline of the Ki-sin-ling, the arch extending up to the mountain tops 3,000 feet 

 or more above the river. The inner part of the anticline in the thin-bedded 

 strata, near the base of the formation, is therefore exposed along the water level, 

 and is seen to be characterized by many sharp folds and possibly by minor over- 

 thrusts. The details could not be followed as we passed, but the major struc- 

 ture was clear. Finally, toward the west, the dip is continuous on the northwestern 

 limb of the arch, and the Sin-t'an shale comes in above the limestone.' The 

 shale is overlaid by the Wu-shan limestone with characteristic black chert of 

 the lowest beds. There is a repetition of the shale and limestone with black 

 chert, occasioned by a slight overthrust at this horizon of adjustment, and then 

 follows the mass of the Wu-shan limestone forming the upper part of the Wu-shan 

 gorge. 



We see that this description differs very materially from my 

 researches. In confirmation of my own views I must remark that it 

 is far more difficult to take careful observations while going rapidly 

 downstream than during the slow course upriver. I myself experi- 

 enced this on my return journey. 



If we now continue the course of the Yang-tzi, below K'uan-tu- 

 k'ou, it will appear that an ever-widening synclinal area is occasioned 

 between two anticlines, viz., the middle anticline of the Wu-shan 

 gorge with its NE-SW trend, which in the NE is probably bent ENE- 

 WSW, and the almost true equatorial trend of the southernmost of 



I This was not observed by me. 



