12 A NATURALIST IN WESTERN CHINA 



about 40 miles below Ichang. At first low, the hills gradually 

 increase in height, and by the time Ichang is reached one is 

 fairly among the mountains. In the vicinity of the town the 

 hills are pyramidal in outline, with prominent cliffs near by ; 

 north, south, and west of the town the country is much cut up, 

 forming an archipelago of peaks 2000 to 4000 feet high, 

 the peaks themselves being offsets from spurs attaining alti- 

 tudes of 7000 to 9000 feet, situated some days' distance beyond. 

 These pyramidal hills around Ichang are very interesting and 

 never fail to attract the attention of travellers. They are 

 made up of a substratum of pebbly conglomerate, on which are 

 reared thin, horizontally deposed strata of marine limestone, 

 red shale and sandstone, over-capped with sandy clays. The 

 strata are piled with great regularity, and when erosion is 

 equal on all sides the characteristic pyramidal shape is pro- 

 duced and maintained. This formation is general from the 

 edge of the great plain to Ichang, and occasionally it contains 

 thin beds of coal. It is of comparatively recent age, dating 

 back to Permo-Mesozoic times. The dominant fossils it 

 contains are Cycads, and the youngest rocks probably belong 

 to the Oolitic series. The cliffs and bold peaks to the north, 

 south, and west of Ichang are made up principally of Paleozoic 

 limestones, with a little shale and sandstone, the latter of the 

 Mesozoic period. The strata are folded in apparent conformity 

 and are without notable metamorphism. In eastern Szechuan 

 these rocks extend beneath the Red Basin. The Yangtsze 

 has forced itself right through them and formed a series of 

 mighty chasms in which the structure of the various forma- 

 tions is beautifully exhibited. 



In the neighbourhood of Hwangling Miao (30 miles west of 

 Ichang), and westwards for 10 miles to the Tungling Rapid, 

 granitic gneiss is exposed. These are the oldest rocks in this 

 region and the only Pre-Cambrian formation known in situ in 

 the Middle Yangtsze. This section of the river is caUed the 

 Ta-shih Ho (River of Dregs and Boulders), and weU does it 

 deserve this appellation. 



The next oldest rocks of importance are those forming the 

 cliffs opposite Nanto, in the Niukan Gorge and in the eastern 

 half of the Wushan Gorge. This is a massive formation 4000 to 



