The Conglomerates, formed of well-worn and rounded pebbles, occur at 

 an altitude of about 500 feet. The Pyrites, a grey and friable variety, occurs 

 at an altitude of between 300 and 400 feet. The sulphur is extracted by the 

 natives, who roast the pyrites in perforated clay vessels, the residue being a 

 soft, earthy substance the colour of yellow ochre. When roasted again, this 

 turns into a bright red powder, largely used in the manufacture of paint for 

 houses and furniture. In places, where the second roasting is carried on, 

 the whole of the surrounding ground, for a considerable distance, becomes 

 stained a bright red. Many such patches mark the slopes of these mountains, 

 and might at first sight be mistaken for outcrops of Red Haematite. 



The coal from this district is also very sulphurous, and unpleasant to use 

 in open grates, being very smoky and giving a large percentage of ash. In 

 places, where the seams were exposed to the air, we often noticed an 

 efflorescence of pure sulphur. 



There is also a considerable amount of iron-ore in these mountains ; and 

 some of the streams in the range are strongly alkaline : a fact especially 

 noticeable when they are frozen. 



After crossing this ridge, we descended first through loess and then 

 through shale to the bed of the Fen Ho at Ku-chao. Here, a little way up 

 the ravines, which join the river, iron-smelting is carried on ; brown iron- 

 ore being easily mined. Iron, coal and clay occur together in these spots ; 

 otherwise, there would be no smelting done. The price of pig-iron is too low 

 to allow of any one of these materials being transported for use from a 

 distance. Baron von Richthofen has described the native method of smelting 

 so well that any further remarks would be superfluous. 



The formations, from Ku-chao westward for a distance of twenty miles, 

 are entirely of Sandstone, Shale and Huang-t'u. As already stated, the strata 

 of these sedimentary rocks were found to be horizontal, and free from foldings 

 and faults. 



At Ts'a-k'ou, about forty-five miles west of T'ai-yuan Fu, Sinian Lime- 

 stone again makes its appearance, and a little further on the Pre-Cambrian 

 rocks, which form the Chiao-ch'eng Shan district, commence. We first 

 travelled up a long valley leading westward, the sides of which were composed 

 of precipitous limestone peaks. As we ascended the pass at the head of this 

 valley, we crossed a dyke of Pegmatite exposed in the cutting of the bridle- 

 path, the rest of the slopes being composed of Mica Schists. On the western 

 slope of the pass, masses of white Felspar with large pieces of embedded 

 Muscovite were noticed. Large stones of both fine and coarse-grained Gran ite , 



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