396 ANNUAL KEPOKT SMITHSONIAN INSTITUTION, 1913. 



tiv€ barrier to travel because they are so continuous and the relief is 

 so gi-eat. Not only is there no waterway but there are no wagon 

 roads, and the building of a railroad would be a stupendous and ex- 

 pensive engineering task. Such a road would necessarily involve the 

 making of a succession of long bridges and tunnels. Here, as in the 

 central ranges, settlements are limited to the rare open spots in the 

 bottoms of valleys, and so the population is sparse indeed. The total 

 commerce is very small in volume, because goods must be carried 

 almost entirely on the backs of coolies. The rugged characteristics 

 of the region are evidently the direct result of the recency of the 

 compressive movement which produced the tremendous mountain 

 folds, and perhaps are still more due to the renewed uplifts which 

 have permitted the streams to continue the carving of their deep 

 gorges. This part of China is geologically very young, and to quote 

 the words of the distinguished old geologist of California, Joseph 

 Le Conte, "the wildness of youth (here) has not yet been tempered 

 by the mellowness of age." 



