CHINA, MONGOLIA, ANP JAPAN. 5 



Flanking this granite core on both sides and covering it, is the great Devonian 

 limestone floor of the Chinese Coal measures. On the eastern flank of the granitic 

 axis the limestone strata trend, almost uniformly, N. E. S. W., varying in dip from 

 25° to 8° towards the S. E. as we recede from the granite. On the western flank 

 the strike is less regular, changing from nearly N. S., at the contact with the meta- 

 morphic schists, to N. E. S. W. in the upper part of the limestone. In the imme- 

 diate neighborhood of the river, over an area of forty or fifty square miles, the 

 limestone has disappeared, but in the distance, on both sides of the Yangtse, its 

 yeUow clifi's are seen towering to a height of more than 2,000 feet above the water. 



I Ivnow of no limestone deposit that can rival this in thickness. Taking the 

 length of the cross section from its contact with the younger conglomerates, near 

 Ichang, to where it rests on the metamorphic schists, to be seven and one-half 

 geographic miles, and the mean dip at 15°, viz., 10° for the eastern half and 20° 

 for the western, we obtain the enormous thickness of 11,600 feet, more than two 

 statute miles. I observed no faults in this gorge, and the great thickness observed 

 in this same limestone in Northern China, leads me to think that the above estimate 

 cannot be far from the truth. 



West of this ridge of limestone is another of about the same size, the interven- 

 ing space being occupied by the Coal measures. 



Here, within a distance of eighty miles, are the principal rapids, while the river 

 traverses the limestone through a series of five gorges iinsurpassed in the grandeur 

 of their scenery. The Yangtse, which, a few miles below the mouth of the Ichang 

 gorge, has a width of 960 yards, is in this narrowed to 250, and in the Fungsiang 

 gorge to 150 yards. -^ In these narrow passages, whose walls are from 900 to 1200 

 feet high, clifi's of bare rock, often vertical or overhanging, alternate with steep 

 declivities clothed in green from the water to the summit, and with deep, inaccessi- 

 ble dells filled with the rich growth of a semi-tropical vegetation. Streams flowing 

 from the mouths of caverns high above the river, cool the air in their descent, while 

 the huge clusters of stalactite which they have formed — the work of ages — show 

 well the chemical power of the smallest drop, side by side with the mechanical force 

 of the rolling river. Through these gloomy chasms the skilful boatmen drag the 

 heavy junks, now " tracking" them from paths and steps hewn in the solid rock, 

 now pulling them by rusty and time-worn chains clamped along the vertical walls. 



The depth of the water must be very great,^ and the difi"erence between high 

 and low water is said to be as much as eighty feet in the Ichang gorge. 



The limestone is generally of a bluish-gray color and compact texture, though 

 subordinate to this variety, layers occur having every shade of color and grain. 

 A gray, compact variety, with frequent large crystals of calcite is not uncom- 

 mon; and a very compact, almost black kind is quarried in the Ichang gorge. 

 Indeed gray, pink, red, black, and blue varieties of this same limestone, with com- 

 pact, poi-phyritic and crystalline textures, furnish in almost every province of China 



* Blackiston. Five montlis on tlie Upper Yangtse. 



- Blackiston's party found no bottom with eighteen fathoms. 



