GEOLOGIC HISTORY OF CHINA — BLACKWELDER. 395 



along tliem it become^ necessary for the boatmen to pole around the 

 cliff or to zigzag from one side of the river to the other to take 

 advantage of every foothold. 



Through the central part of this mountain uplift the great Yangtze 

 River, which in its lower course readily accommodates large ocean- 

 going vessels, has carved a succession of superb gorges. In many 

 places the gray limestone walls rise from 3,000 to 4^000 feet above the 

 river, and the stream is compressed into less than a tenth of its usual 

 width. Difficult and dangerous as are these canyons, beset with 

 rapids and whirlpools, they afford the only ready means of commu- 

 nication between eastern China and the fertile basin of Szechwan, 

 which lies west of the Central Ranges. 



Without the highway of the Yangtze this great Province, four 

 times are large as Illinois and with more people than all of our States 

 east of the Mississippi River, would be unable to export its many rich 

 products or to enjoy the commerce of outside Provinces and nations. 

 It has been effectually barred off from India and Burma by the suc- 

 cession of high ranges and deep canyons which appear to be due 

 primarily to the great epoch of folding in the Miocene period. Sze- 

 chwan is a broad basin which has never been depressed low enough 

 to force the streams to level its bottom with alluvial deposits, as in 

 the Yellow River plain to the east; nor does it seem to have been ele- 

 vated into a high plateau which would have been carved by many 

 streams into a rugged mountain country. The soft red sandstone 

 beds which underlie it have therefore been sculptured into a network 

 of valleys with intervening red hills or buttes. With a climate as 

 mild and moist as that of Alabama, and a diversified topography, 

 there is opportunity for many industries and for the cultivation of a 

 great variety of crops. Szechwan leads all the Provinces in the ex- 

 portation of silk. Here grow the lacquer and oil nut trees and a 

 wide range of field and garden fruits, grains, and vegetables. Ample 

 water for irrigation and especially for rice culture is supplied by the 

 many perennial streams which descend from the encircling moun- 

 tains. These uplifted and now mountainous tracts have also served 

 as a barrier to invaders from all directions, so that this has been less 

 subject to wars than almost any other part of China, and hence has 

 been more stable in development. Its inhabitants are among the 

 most substantial and progressive components of the Chinese nation. 



We now come to the last of the geologic divisions which were laid 

 out for consideration. From the Szechwan Basin southwest to the 

 confines of India there extends a series of high mountain ranges sepa- 

 rated by deep and narrow valleys, all trending in a south or south- 

 easterly direction. Although not so high above sea-level as the moun- 

 tains north and south of Tibet, these ranges are an even more effec- 



