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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 Yang-tze River, which in its lower course readily accommodates large oceangoing 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 communication between eastern China and the fertile basin of Sze-chuan, which lies west of the Central Ranges.

Without the highway of the Yang-tze, this great province, four times as 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 succession of high ranges and deep canyons which appear to be due primarily to the great epoch of folding in the Miocene period. Sze-chuan 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 elevated into a high plateau which would have been carved by many streams into a