6i6 E. C. ABENDANON 



position, has cut its way in a straight canal-hke bed, obhged to do so 

 by the rock structure. 



The Middle Yang-tzi might be called a mature river, and this even 

 after it has been revived, as seems to have been the case only once. 

 The conglomerate bank of principally eruptive pebbles, mentioned 

 above, shows the remains of the floor of a former Yang-tzi valley, in 

 which the river has cut its narrower trench of nowadays. The 

 mighty work here already accomplished by Nature has rendered the 

 Yang-tzi navigable to far above Chung-king, thus making it for a 

 length of more than 2,500 km. one of the most important highroads 

 for trafhc. That which Nature has left undone would be no serious 

 obstacle for the amelioration of this waterway because the obstruc- 

 tions do not consist of falls, but only of rapids as the result of not-yet- 

 washed-away detritus accumulations and partly uneroded dykes of 

 eruptive rocks in the Nan-t'ou granite area. These obstructions, that 

 make steam navigation on the Middle Yang-tzi not yet economically 

 practicable, can, according to my idea, easily be overcome by human 

 technics, and it is by no means beyond financial possibility. This 

 has already been set forth in detail by me in an article, " La naviga- 

 bilite du haut Yang-tzi-kiang par bateaux a vapeur," published in 

 the Revue unwerselle des Mines, at Liege, tome XII, 4e serie, p. 149. 



No doubt the geology of the mountain ranges which are cut by 

 the Yang-tzi between K'ui-chou-fu and I-ch'ang still offer many 

 interesting problems and points of view. But I believe to have given 

 in the foregoing, in general features, the geological structure of this 

 most interesting area as it appears in reality. Indeed, all that I saw 

 of the Red Basin of Ssi-ch'uan and its border parts, leads me to the 

 conviction, that, as for structural geology, this is one of the classic 

 parts of the earth's crust, showing its inner and outer structure in a 

 way to allow of the finest detail studies of folding and erosion, which 

 appear in a pattern of the utmost simplicity and regularity. 



