THE HORIZONTAL MOVEMENT OF GEANTICLINES AND 
THE FRACTURES NEAR THEIR SURFACE 
H. A. BROUWER 
Delft, Holland 
- Most islands of the arcs which lie to the east and the southeast 
of the Asiatic continent show proof of an uplift of the land rela- 
tively to the sea-level, which is amply demonstrated in tropical 
regions by the presence of upheaved fringing reefs. In the East 
Indian Archipelago there exists a striking difference between the 
western and the eastern parts as regards the rising islands and the 
submarine topography. If the sea-level were to be lowered 200 
m., Sumatra, Java, and Borneo would form one mass of land with 
the peninsula of Cambodia and Siam, just as Australia would form 
a single mass with the Aru Islands through the vast tract now 
occupied by the shallow Arafura Sea and the Bay of Carpentaria 
to New Guinea and the islands Misool, Waigeu, Batanta, and 
Salawati to the west of New Guinea. 
Between these two near-land-masses lies an area in which deep 
sea basins alternate with upheaved islands. From a geological 
point of view Verbeek! first drew attention to this remarkable fact, 
of which a more satisfactory discussion has been made possible 
because of the new deep-sea chart of the Siboga Expedition.2 In 
Verbeek’s opinion the elevation of the islands surrounding the 
Banda Sea is the result of folding at greater depth. The active 
forces first began compressing near the surface, and as the geosyn- 
clines were formed they became active at greater depths. Later 
Molengraaff* expressed similar ideas, and for the southeastern por- 
tR. D. M. Verbeek, “‘Rapport sur les Moluques,” édition frangaise du Jaarb. 
v. h. Mynwezen in Ned. O. Indié, Vol. XX XVII (1908), pp. 833, 834. 
2G. A. F. Tydeman, “Hydrographic Results of the Siboga Expedition,” Chart 1, 
in M. Weber, Siboga-Expeditie, Part III, Leyden, 1903. 
3G. A. F. Molengraaff, “Folded Mountain Chains, Overthrust Sheets and Block- 
Faulted Mountains in the East Indian Archipelago,” Compte rendu du XIIe congrés 
géologique international, Toronto, 1913, p. 6990. 
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