68 POPULAR SCIENCE MONTHLY. 



THE GEOLOGY AND GEO-BOTANY OF ASIA.* 

 By prince p. kropotkin. 



THE time has not yet come when the geological history of Asia 

 can be written in full. It appears, however, that, with the 

 exception of a marginal zone in the south, which belongs to the Him- 

 alayan upheavals, the great plateaus of east Asia are built up of crystal- 

 line unstratified rocks, granites, granitites, syenites and diorites, as 

 well as of gneisses, talc and mica-schists, clay-slates and limestones, 

 which all belong to the Archean formation (Huronian, Laurentian, 

 Silurian and partly Devonian). They thus can not have been sub- 

 merged by the sea since the Devonian epoch. The higher terrace of 

 the plateau of Pamir and the plateaus of the Selenga and the Vitim 

 are formed only of Huronian and Laurentian azoic schists; even Si- 

 lurian deposits — widely spread on the plains — are doubtful on the 

 plateaus. Their upheaval must date accordingly from an earlier age, 

 and they must have been a continent during the Devonian epoch, while 

 parts at least of the lower terrace were under the sea at that period. 

 During the Jurassic and Tertiary periods immense fresh-water basins 

 covered the surface of those plateaus; they have left their traces in 

 Jurassic coal-beds, and in Tertiary sands and conglomerates, these 

 latter appearing in mighty layers on the borders and slopes of the 

 plateaus. The chains of mountains which fringe the plateaus along 

 their northwestern and southeastern borders are of the same ancient 

 geological origin. They rose above the Carboniferous, Triassic, Chalk 

 and Jurassic seas which covered what are now the lowlands and lower 

 terraces of Asia; the upheaval of these chains has, however, continued 

 throughout these epochs, so that in the outer chains of Asia we see 

 Carboniferous and younger deposits, up to Tertiary, lifted up to great 

 heights. The same is true of the border-ranges along the southwestern 

 border of the great plateau of east Asia, namely, the Himalayas, which 

 were lifted during the Tertiary age, while at their northern foot, on 

 the surface of what is now the surface of the plateau, traces of Triassic 

 deposits seem to have been found near Lhasa. Carboniferous deposits 

 are met with in Turkestan, India and western Asia; while in eastern 

 Asia the numerous coal-beds of Manchuria, China and the archipela- 

 goes are all Jurassic. As to the age of the plateaus of western Asia, 

 it remains unknown at the present time. 



* From an article in the March number of The Geographical Journal. 



