10 



RESEARCH IN CHINA. 



observe an unconformity between the two, but our observations of other 

 sections, nevertheless, lead us to infer that an unconformable relation is 

 general between the Ta-yang and the Sinian systems. 



Von Richthofen's first section is across the Nan-k'ou range, north- 

 west of Peking, en route to Kalgan. 



SECTION IN THB NAN-K'OU RANGE (VON RICHTHOFEN).* 







Description of the rocks. 



m Evenly bedded limestones without chert , 

 dark gray to blackish; fine-grained; 

 break splintery and conchoidal, some- 

 times uneven. Beds 2 to 12 inches thick, 

 seldom more, well separated from one 

 another. Non-fossiliferous. Here occur 

 the limestones with horizontally em- 

 bedded, flattish, rounded bodies which 

 give worm-like outlines in cross-section. 

 The bodies here consist mostly of dense 

 black, the matrix of crystalline lime- 

 stone. These "Wurmkalke" are every- 

 where characteristic of an upper horizon. 

 Another typical rock is greenish splin- 

 tery limestone. Total thickness 



1 Globulitic limestones, clear gray to black. 

 Globulites mostly size of oat kernels, 

 seldom as large as peas. Beds 2 inches 

 to 2 feet thick. Trilobites abundant .... 



k Green strata 



i Globulitic limestones like 1, predomin- 

 ating, with dense homogeneous lime- 

 stones interbedded 



h 5. Red clay shales 120' 



4. Gray limestone 80' 



3. Red strata 80' 



2. Dense siliceous limestones of flat con- 

 choidal fracture, very evenly bed- 

 ded; whitish, greenish, reddish; 

 prevailingly greenish-white . 200' 

 i . Red clay shales 100' 



g Gray, dense limestone, in part fine- 

 grained crystalline 



f Black and gray sandy clay shales and 

 sandy, in part micaceous slates, partly 

 even, partly curved. (Krummschalig.) 

 Yellow sandstone with iron ore 



e Whitish-gray, fine-grained, crystalline lime- 

 stone, with interrupted interbeddingand 

 knots of black flint 



d Blue crystalline siliceous limestone, in part 

 pure, in part interbedded with thick 

 l>eds of flint. Thickness not determined, 

 but great. 



Thickness 

 (feet). 



500 

 80 



1500 



580 



400 



500 



2500 



Equivalents in terms of this volume. 



The limestone (m) comprises strata which 

 are characteristic of the Tsi-nan and 

 Chau-mi-tien limestones. The non-fos- 

 siliferous condition is specially marked in 

 the former, but fossils are not common in 

 the latter. The "Wurmkalke," conglom- 

 eratic limestones, are well developed at 

 the base of the Chau-mi-tie'n. A distinc- 

 tion between the two would scarcely be 

 recognized in reconnaissance. The thick- 

 ness is less than their combined volume, 

 but the upper part of von Richthofen's 

 section is covered. 



Strata comprised under i, k, and 1 corre- 

 spond to the oolitic limestones and green 

 shales of the Kiu-lung group of Shan-tung. 

 The thickness of oolitic limestone is four 

 times any measure which was there seen. 

 It may be overestimated, but if correct 

 does not affect the probability of close 

 correlation. 



Beds i to 5 inclusive (h) are very character- 

 istic of the Man-t'o formation of Shan- 

 tung. The 200-foot limestone bed is 

 much thicker than any occurring there, 

 but holds a stratigraphic position like 

 that of a thin layer in the type section. 



Beds f and g are unfamiliar; they appear to 

 be upper members of the Ta-yang lime- 

 stone, which were eroded in the sections 

 we observed. 



Beds d and e are typical Ta-yang limestone, 

 and in view of the great thickness, the 

 lithologic identity, and similar position 

 below the Man-t'o, we feel confident of 

 their being equivalent to that formation. 



* China, vol. n, p. 306. 



