HORIZONTAL MOVEMENT OF GEANTICLINES 569 
The further evolution of the geanticline can take place in differ- 
ent ways. If we suppose that in the next stage the plastic defor- 
mation of the northwestern secondary geanticline at greater depth 
causes chiefly a movement in a horizontal direction, the region of 
strongest upheaval will be displaced to the southeast. We may 
suppose that the rows of islands move in the direction of Australia, 
which for our considerations is the same as if Australia moved in 
the direction of the row of islands. Hobbs‘ has pointed out that 
‘mechanical difficulties disappear if the principal active forces in- 
volved in the folding of the Alps are considered as directed from 
the northwest toward the southeast. So far as our general con- 
clusions are concerned, we may consider these movements as rela- 
tive and not as absolute. The upper parts of the secondary 
geanticline do not move at the same rate and the higher parts of 
the folds were originally above the downward-moving secondary 
geosyncline. In a later stage of evolution these may be above the 
rising northwestern secondary geanticline and will be elevated 
above the sea. 
Though differing in details, the geanticline of Timor may repre- 
sent a later stage of geanticline evolution than the Tenimber 
Islands. In Pliocene time the geanticline near Timor was sub- 
jected to prolonged denudation and almost entirely disappeared 
below the sea. The crustal movements resulted in the develop- 
ment of two geanticlines and an intermediate, in part subdivided, 
geosyncline (cf. Molengraaff, op. cit., p. 694), which became 
throughout fairly well filled by an accumulation of late Tertiary 
sediments deposited during a period of slow subsidence. Flexures 
and faults of considerable horizontal extent occur in the limbs of 
the geosyncline, which have caused the Pliocene strata within the 
basin to become bent abruptly upward near the edges. These 
longitudinal flexures and faults, which are essentially the same 
phenomenon, are the surface expression of an earlier, more plastic _ 
deformation at greater depth. Reefs and other littoral deposits 
spread over a great area, and after a certain period of evolution a 
great portion of Timor must have been covered by a sea full of 
™W. H. Hobbs, “Mechanics of Formation of Arcuate Mountains,” Journal of 
Geology, Vol. XXII (1914), p. 85. 
