66 RESEARCH IN CHINA. 



These notes suffice to trace the marine connection of Central China 

 with Europe by a route south of the Tibetan plateau region, and thus to 

 bring out the fact that the interior sea of Asia, the Tethys, during middle 

 Paleozoic time completely surrounded the plateau region, which was prob- 

 ably a land area. 



MIDDLE PALEOZOIC DIASTROPHISM. 



Diastrophic movements in China during the middle Paleozoic were 

 very slight. As has been brought out in discussing the sedimentation 

 of the Silurian and Devonian periods, there was no considerable deposition 

 of marine sediment, no evident accumulation of continental deposits, no 

 notable depth of erosion. A stable condition of the southeastern conti- 

 nental masses is plainly indicated. 



A similar inference holds for Gondwana Land in the peninsula of India 

 and the Tibetan mass, so far as we may draw one from the meager sedi- 

 mentation that represents Silurian (Gothlandian) and Devonian in the 

 Himalayas : a few hundred feet of limestone and quartzite ; the lands were 

 not high. 



A somewhat different suggestion lies in the Devonian and Silurian (?) 

 deposits of northern Tibet, which Obrutchov, the explorer of the Nan-shan 

 system, describes as quartzites and shales of great thickness. They appear 

 to represent an epoch of vigorous denudation, and their volume seems to 

 stand for an elevation equivalent to a mountain range. According to 

 Bogdanovitch, there is an overlap of middle and upper Devonian onto 

 an eroded surface which exposes granite; the elevation had, therefore, by 

 middle Devonian time, given place to peneplanation and subsidence; he 

 regards this invasion of the sea as an event of prime importance and 

 designates it the Kuen-lung transgression. 



It is not clear what the nature of the elevation was: an orogenic 

 movement, perhaps accompanied by granitic intrusion, or an upwarp 

 without folding or visible intrusion? Comparison with the Taconic dis- 

 turbance in New England or the Caledonian movement in Scotland, both 

 during Silurian time, tempts speculation to postulate a similar orogenic 

 event in central Asia; but the conservative position taken by Suess* in 

 deferring a correlation of these events is the sound one in the limited state 

 of knowledge. This attitude is the more reasonable because the Taconic 

 and Caledonian disturbances are geographically and presumably causally 

 related to the Atlantic basin, whereas the region in central Asia belongs to 

 a distinct continental province. 



*Beitrage zur Stratigraphie Zentral Asiens, in Denkschriften der k. Akad. Wiss., LXI, 1894, P- 435- 



