Tectonic Geography of Asia. Hobbs. 143 
pressed tlian the other parts of the East Asian steps formerly designat- 
ed as coastal. 
(e) The general form of the interior land blocks lying to the north 
of the Tsinling monntains, which is conditioned through the general 
rise of the included land surface in the direction of a more highly 
elevated border, and the shorter descent, probably depending upon step 
faulting toward the seaward, is represented in the T^ngusian and Kor- 
ean marginal blocks. The marginal bulging up is lacking to the Chi- 
nese crescent, but is present on the other hand in the meridional part 
of the Annamitic. 
The general arrangement of each individual coast crescent is inde- 
pendent of the internal structure as has already been, get forth as true 
of the interior land blocks. But the proportion is a special one in the 
case of each crescent. 
M.\NNER AND .\GE OF THE TECTONIC MOVEMENT. 
(a) As little as the crescents of the interior series do the exterior 
ones correspond morphologically and tectonically with the folding and 
overthrusting of the connected mountain scallops upon the convex side, 
though in their linear outlines they more resemble them than those of 
the former series. In the case of the Tungusian crescent it is not 
proven that very old, perhaps even Archean, folds do not stand in some 
relation with its position ; but on the one hand parts of it cut too sharp- 
ly through the axes of folds in order to bring both into complete caus- 
al connection ; on the other hand it is only one member of a series of 
externally homologous structures whose form must be referred to a 
similar action of forces. Since now in the case of the other three cres- 
cents a correspondence with the internal structure cannot be made out, 
we may measure with it the fact that in the case of the Tungusian 
crescent such a correspondence is in part present, as having a secondary 
significance only. 
(c) The continental mass of eastern Asia may be considered to 
have been depressed in great blocks. Two of these are distinctly indi- 
cated through widely extended crescentic lines in sections depending 
upon the formation of fractures. The one cause of the phenomenon is 
to be sought in the combination of two systems of tensional forces of 
which one was directed eastwards, the other southwards. 
If we seek for the cause for the development of the eastwardly di- 
rected tension it may be sufficiently given in the depression of the Pa- 
cific ocean basin on the border of the continental mass presumedly de- 
pending upon isostatic tendencies continuing through long periods. . . 
. . The Eastern Asiatic festoon of islands appear as the crest of the 
marginal region of the continental mass arched up through such upward 
working stresses. But since they bear the character of the inner side 
of fold mountains, the folded outer zone must be sought first in the 
descent toward the oceanic depth. The existence of other still deeper 
lying crescents projecting only in small island peaks and otherwise still 
hidden beneath the surface of the sea, as they stand forth upon bathe- 
