798 



above (he level of the sea and in Roma they ^) have reached con- 

 siderable heights. However, as far as the islands west of Wetter 

 are concerned, onr assnmption, (hat volcanic action lasted (he longei 

 (he more the islands were removed westwards from Wetter, is borne 

 ont b}' (he occurrence of eleva(ed coral reefs. 



e. Whedier there has been a shifting of (he volcanic action in 

 a direction perpendicular to the lOw of islands cannot be well 

 made out. 



I( might be supposed, (ha( i( has shifted inward, because (o-daj 

 volcanoes occur only in (he inner row; but (he presen( configura- 

 (ions of the landsurface resulted from the recent crns(al-movemen(s 

 and the region north of (he islands in fig. 1, is nowadays covered 

 by (he sea. The volcanic ac(ion may, in the tertiary period, have 

 affected a broader tract, while at present it is confined to a narrower 

 strip comprising the inner row of islands. 



Having recorded these characteristics, we will now discuss first 

 of all (he origin and (he shape of the two curving rows of islands. 



Origin of the roios of islands. 



In an earlier paper we have demonstrated') that (he elevation of 

 (he islands, encircled by deep ocean-basins, must be looked upon as 

 a result of renewed nu)untain-building forces and (ha( (hese move- 

 ments, just as (he (erdary, are ap( to proceed towards (he "Vorland". 

 Their intensi(y has been variable, nor was i( equal for various 

 parts of one and the same row in a definite period, so that some 

 parts may rise higher than (he other and locally also subsidence 

 may occur. We will confine ourselves (o (he region under consider- 

 ation. In Timor a period of intensive crustal movements, persisdng 

 into the miocene, was succeeded by a prolonged dejiudation of the 

 landmasses emerging from the sea. A large part of (he island has 

 af(erwards been submerged again and a pliocene formation, whose 

 oldest deposits consist of pure Globigerina-limestone devoid of terri- 

 genous elements rests unconformably on (he older formations, as 

 has been discussed in detail by Moi.engraaff ') *j. In plio-pleistocene 



1) lb., p. 435. 



2) H. A. Brouwer, 1. c. 



3) G. A. F. MoLENGRAAFF, Folded mountain chains, overthrust sheets and block- 

 faulted mountains in the East-Indian archipelago. G. R. Xllf' congr. geol. intern. 

 Toronto 19i;'>, p. 693 



*) Ibid. On recent crustal movements in the island of Timor and their bearing 

 on the geological history of the East-Indian Archipelago, Proc. Kon. Ak. v. Wet., 

 29 June 1902. 



