68 RESEARCH IN CHINA. 



He then proceeds : 



There follow, in a relation which I am not able to determine clearly, but apparently 

 conformably, a series of deposits which begin with bright-colored clays. They are in 

 part stratified, in part without recognizable structure, and fill inequalities in the eroded 

 dolomite. 



Farther north, in the province of Liau-tung, von Richthofen describes 

 the sequence in the coal-field of T'ai-p'ing,* and gives the following section: 



Limestone, which is heavily bedded and characterized by yellow markings that resem- 

 ble corals but are indistinct in outline on the kidney-brown background, and which does 

 not contain flint, is followed by yellow dolomitic limestone, thin-bedded yellow dolomite 

 with limonite, red ferruginous clays with kidneys and nodules of hematite and limonite, 

 white sandstone, and coal. 



On the margin of the great coal-field of southeastern Shan-si the 

 explorer ascended from Hwai-king-fu to the coal-measure plateau and 

 observed the contact of the coal-bearing T'ai-yang series with an underlying 

 limestone in the type locality. He says :f 



Coal and iron district of T'ai-yang. Throughout a long distance on the west side of 

 the Pi-lo-shan the loess hides the strata above the limestone ; but before one reaches T'ai- 

 yang one has opportunity to see them in beautiful exposures, for there the firm rock forms 

 a flat ridge which connects the limestone range with the mountains that rise further west. 

 They consist of an alternation of sandstone, bright clays, yellow dolomite, rauchwacke, 

 and limestone with flint nodules. I was particularly struck with the analogy of the system 

 in this region with that which occurs at Po-shan-hie"n in Shan-tung, between the limestone 

 and the coal-bearing sandstone. Here, as well as there, the clays are used for making 

 pottery. In both localities the iron ores are related to the dolomites. They do not, how- 

 ever, occur interbedded with them, as indeed the rocks of this horizon are in general not 

 clearly stratified, but exhibit the most striking irregularities in short distances. Here the 

 surface of the dolomite is full of caverns without order, and in these the iron ores are 

 especially common. 



The figures on page 410 of the volume illustrate the observed relations 

 between the coal-measures and the underlying limestone, and show the two 

 to be conformable in dip except in one locality, figure 86, which is, however, 

 not described in the text. 



The observations which von Richthofen may have made in the course 

 of his journey from Canton to Han-kow have unfortunately not been 

 published. He crossed the extensive coal-fields of Hunan and particularly 

 examined that on the Lui-ho, a branch of the great Hsiang-kiang, which 

 flows into Tung-ting lake. From the fact that coal-measure plants occur in 

 abundance t we infer that the Carboniferous strata resemble those of the 



* China, vol. n, p. 287. 

 t/Wrf., vol. n, p. 411. 

 t Ibid., vol. i, p. xxxn. 



