Travelling southward from Yu-lin Fu to Yen-an Ku we encountered 

 Huaitg-t'u formation upon horizontal strata of sandstone and shale. The 

 sandstone in places shows very marked bedding, and, owing to the deposition 

 of mica between the layers, can be split without difficulty. This strongly- 

 bedded sandstone occurs chiefly between Sui-t^ Chou and Ma-chia-k'ou. A 

 good illustration of this may be seen in the photograph of icicles, taken about 

 three miles south of Ch'ing-chien Hsien (Plate 17). The photograph shows 

 too a typical source of the plentiful water-supply to be found in every ravine of 

 North Shensi. 



At Yen-an Fu, the sandstone, still of a pale greenish colour, continues to 

 show marked bedding. At low levels a pink and green cross-bedded sandstone 

 was noted. In the region of Yen-an, the sandstone contains many crystals of 

 Iron Pyrites. These, of course, where exposed, are very much oxidised, but 

 some fine unoxidised specimens were secured at Lao-shan. 



There is little to say about the Huang-Vu of this vicinity, except that 

 at the ravine-bottoms it is inclined to be clayey, resembling Shao-Vu rather 

 than loess. In the wooded area — which extends in a great belt, east and west, 

 some twelve miles south of Yen-an Fu — there is an even greater predominance 

 of Shao-t'u. Here also finely-laminated, dark blue-grey shale occurs just 

 above the sandstone. 



Coal is mined at various places along the route from Yii-lin Fu to Yen-an 

 Fu. Seams, reached by rather deep vertical shafts and showing no outcrops, 

 occur within a mile of the former place. These mines produce a good- 

 burning, but rather smoky, bituminous coal. At Sui-te Chou, a peculiar coal 

 was secured : it was said to have been transported from Ning-hsia, on the 

 western border of the Ordos. It is very heavy and dirty, but absolutely 

 smokeless, and smoulders like charcoal. Once ignited, it will continue to 

 burn with a dull glow till the mass is reduced to soft white ash. The substance 

 is certainly not charcoal, and those who sold it said that it was mined like 

 coal. It has neither the appearance, nor the lustre of graphite. At Ch'ing- 

 chien a fine quality of lignite is obtainable. This comes from mines at An- 

 ting Hsien, a town situated some twenty miles to the north-west of Ch'ing- 

 chien. At Ma-chia-k'ou a very poor quality of coal occurs. This ignites 

 only with the greatest difficulty, and leaves an enormous percentage of ash. 



Yen-ch'ang Hsien, a town situated about forty miles east of Yen-an Fu, 

 is famous for its petroleum wells ; which are worked with European machinery, 

 and produce a high grade of oil. We bought a supply of the oil, and found it 

 burn well. It is sold at the rate of 2jd. per catty (i catty=i| lbs.) and finds 



123 



