88 RESEARCH IN CHINA. 



Strata which we provisionally assign to the Jurassic occur at Sh'i- 

 ts'iian-hien on the Han river, in the form of red and yellow sandstone and 

 conglomerate composed of the detritus from older rocks of the vicinity. 

 The area is apparently limited and owes its present position and preser- 

 vation from erosion to a fault by which the soft young strata are brought 

 to a relatively low level among the metamorphosed Paleozoics.* 



Still farther west, in the northern margin of the Red Basin, are the 

 Jurassic beds near Kuan-yuan-hien, which were first recognized by von 

 Richthofenf, again observed by I^oczy.J and repeatedly referred to in this 

 work. Von Richthofen's section is quoted in volume I, page 295. Above 

 the coal-bearing middle Jurassic, as determined by plant remains, come 

 coarse conglomerates, 300 feet, 90 meters, thick, followed by yellow, reddish, 

 and finally greenish sandstones about 200 feet, 60 meters, thick. The con- 

 glomerates appear to mark an invasion of coarse material of local origin, 

 which may be ascribed to increasing declivities or to greater precipitation 

 in nearby mountains. Together with the overlying sandstone it may with 

 reason be referred to the middle or upper Jurassic. 



This occurrence is presumably typical for the Red Basin of Ssi-ch'uan, 

 so far as its margins are concerned. Although von Richthofen made more 

 extensive observations in this great interior depression of western China 

 than any one since, we have no account of them and rely upon Loczy, 

 who traversed the northwestern margin. He states : 



Immediately upon the early Paleozoic deposits, on the margin of the basin, follow 

 the Mesozoic strata. In the vicinity of Ja-ch6u-fu the Carboniferous appears to be wanting, 

 as immediately beneath the Ssi-ch'uan sandstone we found Devonian limestone near 

 Hoa-ling-pu. Near Kuan-juon, on the other hand, the Carboniferous and Permian strata 

 probably occur in the marginal mountains, as has been stated above. 



The Mesozoic systems are represented by the great series of the Ssi'-ch'uan sandstones. 

 This sandstone formation consists of red and gray sandstones, coarse conglomerates, and 

 marly shales, and in its lower layers are huge coal-beds, which are worked at many points 

 about the northern and western margins. The coal-beds near Kuan-juon-shien and 

 Hoani-pu yielded impressions of plants of the middle Jura (Dogger), whereas near Lin- 

 tschi-shien and Ni-tou we collected Liassic plants. 



Marine fossils are not yet known from the Ssi'-ch'uan sandstone. The only fragment 

 of a mollusk is a doubtful Anoplophora (Cardinia) which was found near Lin-tschi-shien, 

 but it is not sufficiently well preserved to afford definite evidence for or against a marine 

 origin. 



The Ssi'-ch'uan red series is petrographically as well as geologically and structurally 

 identical with the red sandstone of the province of Kiang si, as well as with the basin 

 deposits which we saw on the lower Han-kiang and on the Si-ho. 



* Research in China, vol. I, p. 316 

 t China, vol. n, p. 603. 



I Reise des Grafen Szchenyi, vol. i, p. 440. 

 /<*, pp. 685-686. 



