820 



III virtue of the changes which this axis undergoes in a certain 

 space of time, the inclination may increase in some places, decrease 

 in others. If we suppose the top of the geanticline to lemain in 

 the same place, the different points of the axis will, at an increase 

 of inclination, perform movements on either side, which are horizontal 

 towards the top and vertical in a downward direction. Also with a 

 slight rise of the lop, downward as well as horizontal movements 

 maj occnr at a lower level along the axis. In this case it will, at 

 a certain stage of the evolution of the geanticlinal axis, depend on 

 the height of the sealevel, whether a i-eef formed at this time will 

 be moved np or down. The displacement of the reef will invariably 

 be also in a horizontal direction, fault-movements are left out of 

 consideration here. Conversely the transverse coasts may rise, while 

 the top of the geanticline is descending at a certain height of the 

 sealevel. 



Generally the top will not remain in the same place, hut will be 

 moved both in hoiizontal and in vertical direction ; moreo\ ei' the 

 inclination on either side of the top will not decrea.se or increase 

 in the same way. It does not follow that during these irregular 

 movements the transverse coasts will exhibit a similar behaviour, 

 and generally speaking it may be said that, if the distance from 

 the top of the geanticlinal axis to the coastline, i.e. in the case of 

 the largei' islands, be sufïiciently great, the vertical component of 

 the direction of the movemeni at the t0|)S need not be similarly 

 directed to that at the points of intersections of the geanticlinal axis 

 and the sealevel. This vertical component varies at various points 

 along the axis. 



The inclined geanticlinal axes in the present-day stage of mountain 

 building e.g. are easily distinguishable in the islands of the Timor 

 group separated by straits, and from the al)Ove it may be inferred 

 first of all that the rate of movement latterly observed on the trans- 

 verse coasts -of the larger islands, is not necessarily equal to the 

 rate of movement of the tops, nor need it be of the same direction. 

 This also holds for the earlier stages of the mountain building 

 process. Secondly it afipears, therefore, that the height to which a 

 reef has been upheaved, by no means depends only on the time 

 elapsed since its formation, but on the evolution of the geanticlinal 

 axis so that reefs of the same age may be elevated to different 

 heights') and the highest reefs may sometimes not be the oldest. 



1) As e.g. in Timor. Cf. G. A. F. Molengraaff. 1. c, p. 132 and J. Wanner, 

 Geologie van West-Timor. Geo). Rundschau IV. 1913, p. 139. 



