WESTERN TS'lN-UNG-SHAN. 19 



Loczy, whose observations of the eastern Ts'in-ling-shan have already 

 been described, recrossed the range on the borders of Tibet, 65 miles, 100 

 kilometers, west of von Rich thof en's route. Obrutchov followed the same 

 way southward from "Hoj-shien" to "Quan-jiion-shien," and returned 

 northward by a route that diverges to the west and leads over Min-chou to 

 Lan-chou-fu. The two geologists agree in describing the structure as that 

 of close folding, involving overturned folds and overthrusts. They both 

 observed more or less metamorphosed Paleozoic strata, which make up 

 the great mass of the range, and among which Silurian, Devonian, and 

 Carboniferous horizons are distinguished by fossils.* They also noted 

 metamorphic schists of uncertain age, which are doubtfully assigned to the 

 "Archean" by Loczy, and by Obrutchov are distinguished from the Paleo- 

 zoics under the general term of "metamorphic schists." 



The section in which the "Archean?" rocks are most prominent lies 

 between " Lo-jan-shien " (Lo-yan-hien) and " Tschau-tjen " (Chau-tien) in 

 longitude 106 20', between latitude 32 30' and 33 30' north. It is in the 

 strike of a wide belt observed by von Richthofen, 45 miles, 70 kilometers, 

 further east, which on the basis of the general stratigraphic sequence was 

 classed by him as of Paleozoic age; and 80 miles, 125 kilometers, still 

 further east, near Ssi-mou-ti, we crossed gneisses, schist, and marble, which 

 are intruded by large granite masses and which we also regard as meta- 

 morphosed Paleozoics.f 



In the particular section of the western Ts'in-ling-shan under discus- 

 sion, between Lo-yan-hien and Chau-tien, Loczy mentions the occurrence 

 of crystalline schists, gneiss, and phyllite, and crystalline limestone, which 

 lie in isoclinal folds and are intruded by large bodies of diorite. He dis- 

 tinguishes argillites, chloritic schists, and epidotic schists, as well as partly 

 metamorphosed Paleozoic strata, from underlying gneisses, with which they 

 are, however, folded. And he cites occurrences of fossiliferous Devonian 

 and Carboniferous strata in nearby localities. The sections which he has 

 drawn showj that the rocks which, on account of petrographic likeness, 

 he has classed together, occupy a variety of positions with reference to those 

 whose age is more surely established. The schists under discussion are 

 indicated by a red tint and blue dashes. In section 2, profile plate 2, 

 north of Lo-yan-hien, they appear overlying less highly metamorphosed 

 "Wu-t'ai?" schists on one side and "early Paleozoic limestone" on the 

 other, in a syncline; south of Lo-yan-hien, in the "Pej-ho-scha," they under- 

 lie "Silurian" strata and rest upon granite. Still further south, beyond 



*Reise des Grafen Szechenyi in Ostasien, vol. I, pp. 422-439, plates u and vi. La Face de la Terre, 

 Suess, vol. in, pp. 270-271, fig. 35. 

 tVol. i, pp. 308-310. 

 tReise des Grafen Sze'chenyi, vol. I, pp. 465 and 428, plate n. 



