56 RESEARCH IN CHINA. 



At the top, in a pink limestone, Blackwelder found a few fossils which 

 Girty and Bassler have studied.* They are not able to agree on a definite 

 correlation, but state that, whereas the bryozoa indicate an age correspond- 

 ing to the American Mississippian, the brachiopods do not resemble any 

 Mississippian fauna, and if they stood alone would lead Girty to class them 

 as possibly Silurian (Gothlandian) . The presumption is that the horizon 

 is at least late Devonian or lower Carboniferous, but if so the fauna is unlike 

 others of those times previously collected in China. 



This stratum of pink limestone lies but a few feet below the Wu-shan 

 limestone and 1,500 feet, 450 meters, below a thin bed of anthracite, next to 

 which Blackwelder collected a Chonetes of upper Carboniferous affinities. 



Silurian and Devonian strata in central China were first described by 

 von Richthofen, who came upon them in southwestern Shen-si and northern 

 Ssi'-ch'uan, en route from Han-chung-fu, longitude 107 12', latitude 32 50' 

 to Kuan-yuan -hien, longitude 106 15', latitude 32 20'. They there form 

 the southernmost ranges of the Ts'in-ling-shan, north of the Red Basin 

 of Ssi'-ch'uan, and are intricately folded and overthrust. The strata are, 

 however, richly fossiliferous, and have consequently been well identified. 



South of the town of Ning-kiang-chou von Richthofen crossed an 

 anticlinal range, overturned toward the south, from which he obtained 

 the following section. f (The strata are designated in the accompanying 

 figures and discussion by the letters / to e in ascending order.) 



(/) Limestone alternating with other strata, namely, gray, splintery, siliceous lime- 

 stone, 15 feet; clay shales; lydite conglomerate, and lydite sandstone. The pebbles of 

 the conglomerate in some of the beds are much rounded, in others they are rounded on the 

 corners, and in still others they are quite angular and sharp-edged. The sandstones are 

 practically a fine-grained conglomerate of the same kind. Thereupon follow, in continu- 

 ous alternation, shales and limestones in groups of varying thicknesses. Characteristic 

 are: red limestones, red calcareous marls which break up in friable shaly pieces, and also 

 green, somewhat crystalline limestone, yellow and green calcareous marls, etc. 



The limestone layers are full of well-preserved fossils; in the upper parts trilobites 

 and brachiopods predominate (among them Orthis calligramma and Spirijer radiatus) ; in 

 the lower, crinoid stems and corals. Dr. Kayser determines the age as middle .Silurian 

 approximately equivalent to the upper Llandovery. 



Adjacent to the exposures of / and underlying that terrane in the 

 overturned limb of the anticline comes a formation k and others in sequence, 

 as follows: 



(k) A great thickness of green clay shales, with occasional thin limestone layers, in 

 which brachiopods occur. 



*Vol. i, pp. 273-274. 

 t China, vol. n, p. 596. 



