76 RESEARCH IN CHINA. 



(cb) Dark coal-bearing shale, with slickens covered with calcite. The thickness of 

 this bed could not be estimated closely on account of loose stuff on the slope, but I could 

 see by the position of the tunnels that below this shale occurred 



(cc) the principal coal-bed. From the height of the slope the thickness of cb and cc 

 may be estimated at 1 8 to 20 meters. 



(d) Dark or black bituminous clay marls, with fine calcite veins and full of fossils ; 

 including also yellowish-gray layers of mussel shells. I saw these only on the dumps ; the 

 thickness is therefore unknown, and I can only infer that they occur below the coal-bed. 



(e) Gray, bituminous, marly limestone, which occurs on the southern slope from the 

 mines and in the foot of the principal mine; which alternates with thin layers of coal, and 

 which is full of fossils. 



(/) Yellow sandstone, colored with iron hydroxide and in part shaly. 



The thickness of the strata included from d to / is uncertain, as the base of / was not 

 visible; but all the strata seen on the southern side of the basin lie unconformably on the 

 Nan-shan sandstone, which dips steeply toward the south. 



L6czy gives a list of fossils which serve to correlate the strata with the 

 Russian Upper Carboniferous (Mjatschkowo). 



There are many references in the works of Obrutchov to coal-bearing 

 strata in Mongolia and the Nan-shan. In some cases they are identified 

 as Carboniferous, and in others as supra-Carboniferous. The conditions 

 which prevailed in Shan-si were general throughout central Asia north 

 of the Tibetan arm of the Tethys, and the deposition of continental deposits 

 containing coal, yet interbedded with occasional marine limestones, was 

 wide-spread. The area thus characterized reached into Turkestan on the 

 west, perhaps, as far as longitude 80 east, but was bounded by a sea on the 

 northwest, where the Carboniferous limestone of the Ti6n-shan mountain 

 system was being deposited. 



