HORIZONTAL MOVEMENT OF GEANTICLINES 571 
pass, through a stage with a secondary geosyncline between two 
secondary geanticlines. 
After the Plio-Pleistocene reefs had been formed, a general 
elevation of the island of Timor took place. The elevation of the 
land has been somewhat greater at the edges of the secondary 
geosyncline than in the geosyncline itself, but the general movement 
resulted in the formation of a large anticline with the highest ele- 
vated reefs in the central part of the present island. In this latter 
stage of evolution the horizontal movements near the surface may 
have had a much smaller rate of movement than those at greater 
depth, while the central basin was gradually upheaved above the 
sea. The horizontal movement at greater depth may have pre- 
vailed in one of the secondary geanticlines only, but this is not a 
necessary condition. In our Figure 4 one of the possible modes 
_of upheaval is represented. 
DIFFERENT TYPES OF GEANTICLINAL MOVEMENT 
The movement of a geanticline can be broadly described in the 
first place, in terms of the movements of the projections of the 
geanticlinal axis on the horizontal plane and on a vertical plane 
approximately parallel to the part of the geanticlinal axis under 
consideration. It is next of importance to take note of the move- 
ment of the section of the surface of the geanticline with a vertical 
plane at right angles to the geanticlinal axis. At the beginning of 
the movement we consider the geanticlinal axis to be a straight 
line; in a later stage this line will not be the geanticlinal axis, but 
for an approximate judgment this method is sufficient. ‘The pro- 
jections would undergo no changes in form if the geanticlinal axis 
was displaced parallel to itself. In general the vertical as well as 
the horizontal projection will develop a curved form. Some general 
types are given in Figure 5. 
In Diagram I of Figure 5 the differences of plasticity and rate 
of movement between the surface and the deep-seated parts will 
have an influence on the development of longitudinal fractures 
only. The deformation of the sections perpendicular to the geanti- 
clinal axis will be influenced by the place, the speed, and the 
duration of these fracture movements. 
