THE GEOLOGIC HISTORY OF CHINA 121 



merce, therefore, depend on the agency of pack animals or coolies, and 

 the roads they follow are mere trails winding around the steep moun- 

 tain sides or threading the bottoms of narrow valleys, where swift 

 streams must be forded at frequent intervals. Under such circum- 

 stances it is evident that there can be but little effective traffic. Only 

 comparatively light and expensive articles can be transported long dis- 

 tances. Around the edges of the mountain mass where the populous 

 cities of the adjoining plains can be reached with one or two days' travel, 

 there has been for centuries an important trade in lumber. The moun- 

 tains have now been so largely deforested, however, that it is necessary 

 to go farther and farther back into the heads of the valleys to find large 

 trees. Hence, only the more expensive kinds of lumber such as coffin 

 boards — which are absolutely indispensable, even to the poorer classes, 

 — can profitably be brought out. These are often carried for 20 or 30 

 miles on the backs of coolies — a costly mode of transportation. The 

 smaller trees and brush the mountaineers convert into charcoal, which 

 they carry on their own backs down to the towns along the foothills. 



Lack of transportation facilities is doubtless the chief reason why 

 the opium poppy has in the past been widely cultivated in this part of 

 China, although the practise has lately been prohibited by the govern- 

 ment. The advantage in poppy culture was that it could be carried on 

 in small scattered fields and the product was so valuable for unit of 

 weight that it would pay for long-distance transportation across the 

 mountains. The inhabitants of the region themselves were not, how- 

 ever, generally addicted to the use of the drug. 



The rainfall of the central mountain region is sufficient to supply 

 the many springs and tributary brooks of which the people have 

 made use in irrigation. The mildness of the climate here permits the 

 growing of rice, and by terracing the hillsides they are able to make a 

 succession of narrow curved basins in which the aquatic crop may be 

 grown. For the cultivation of rice it is necessary that the fields be com- 

 pletely submerged during part of the season, and so there must be a 

 plentiful supply of water. 



On the larger rivers such as the Han and the Yang-tze, and their 

 chief tributaries, boats are successfully used. In fact, the Chinese 

 river boatmen are so skilful in the handling of their high-prowed skiffs, 

 that they navigate canyons full of rapids which most of us would con- 

 sider too dangerous to attempt. The descent of one of these rivers is 

 an easy although exciting experience. The return trip, however, is slow 

 and laborious, for the boats must be dragged upstream by coolies har- 

 nessed to a long bamboo rope, which has the advantage of being very 

 light as well as strong. In the many places where the river banks are so 

 precipitous that it is impossible to walk along them, it becomes neces- 



VOL. LXXXII. — 9. 



