564 H. A. BROUWER 
depend upon the direction and the rates of movement at different 
depths. If a geanticline is elevated above the sea, the deeper- 
seated parts will gradually be uncovered by erosion and the surface 
of the geanticline will in time consist of rocks which were in the 
zone of flow during an earlier stage of the mountain-building 
process. As they are approaching the earth’s surface, the rate and 
the direction of the motion may differ more and more from those 
at greater depths on the same vertical line. 
That older folds terminate abruptly against the present coast 
lines is a phenomenon which is well known from Japan and from 
several islands of the East Indian Archipelago (Fig. 1). Particu- 
larly on Ceram this fact is very strikingly exemplified. In the 
Gas 
oy ws 
Fic. 1.—Older folds terminating abruptly against the present coast lines of the 
island of Ceram. (East Indian Archipelago.) Scale 1:3,000,000.  __.... Approximate 
Tertiary strike. 
greater part of the island the strike of the Tertiary mountain range 
is NW.-S.E., whereas the present coast line has for the middle 
part an east-west direction, so that the ridges of the high moun- 
tains terminate abruptly near Taluti Bay on the south coast and 
near Savai Bay on the north coast. 
Similar facts have been explained by von Richthofen™ as a 
result of tensional stress on a large scale, and he believed that the 
mountain arcs of eastern Asia, although bearing a great resem- 
blance to the Alps and the Himalayas, have been formed by ten- 
sional, and not by compressional stress. Various authors have 
pointed out that this conception is not exact, and particularly 
because the fractures resulting from tensional stress are generally 
straight, whereas the ranges which lie to the eastward of the 
« F. von Richthofen, “‘Geomorphologische Studien aus Ost-Asien, IV,”’ Sztzungsber. 
der Berlin. Akad. der Wiss., XL (1913). 
