OF ARTS AND SCIENCES: MAY 25, 1869. 119 



is surrounded by a narrow ring of these beds, which are horizontally 

 stratified and form the slopes of the volcanoes up to an altitude of four 

 hundred feet. They probably owe this singularly isolated position to 

 a local elevation of the volcanic district, which may have taken place 

 loner after its vents were extinct. 



d. Loess, which cannot be distinguished from the European Loess. 

 It comnoses terraces two hundred feet hia;h, and contains shells of 

 Helix. It is sometimes separated from the underlying rocks by a 

 layer of Laterite. 



e. Alluvium of the great plain. 



The different formations here enumerated compose, on the right and 

 left bank of the lower Yang-tse, a series of detached and apparently 

 disconnected mountain ranges. The complete sequence of sedimen- 

 tary formation can only be constructed out of the various part-sections 

 which those ranges severally afford. But no sooner are the geological 

 columns put down on a map than the unity of the whole system of 

 ranges is. conspicuous. They form together, so to say, one great geo- 

 logical range, which is directed from southwest to northeast, parallel 

 to the course of the Yang-tse from Kiu-kiang to Nan-king. There may 

 be distinguished an axial core, consisting of the three most ancient 

 formations and granite, while those of subsequent age ai'e distributed 

 on both flanks of it. On the northwestern flank a somewhat regular 

 sequence of them may be observed, commencing with those following im- 

 mediately on the granite, and ending with the post-porphyritic deposits. 

 It forms, between the Liu-shan and Han-kau, a belt of one hundred 

 and fifty miles in breadth, and is cut at right angles by the Yang-tse. 

 The hills between Chin^-kiano; and Nan-kin^ constitute a belt of 

 similar construction, though much more narrow, on the southeastern 

 flank. I use the term "axial core" in a purely geological sense, as 

 the formations composing it do by no means occupy the centre of 

 actual mountain ranges, nor do they excel by the altitude to which 

 they rise. Though the granitic mountains near Ngan-king are about 

 three thousand five hundred feet high, most of the hills composed of 

 those ancient formations would but slightly attract the attention of the 

 topographer. West of Poyang Lake, for instance, the upturned edges 

 of the oldest sediments constitute a low plateau, and rise only in a 

 few hills to about six hundred feet, while the more recent Tung-ting 

 grits compose, in the immediate vicinity, the high and abrupt range of 

 the Liu-shan. 



