800 



nearly parallel with the present inner row with the joung active 

 volcanoes. 



The characteristics of the rows of elevated islands and of the 

 deep seahasins between them are indicative of a renewal of the 

 mountain-building process which, in the miocene period has pushed 

 the mesozoic and anterior tertiary sediments in the direction of the 

 "Vorland." They are not contrary to the assumption, that these 

 movements take place again in the direction of the Vorland. When 

 these movements persist, the rising of the islands will be attended 

 with a removal in that direction, as e.g. was the case with the 

 Kei Islands ever since the miocene movements. The sea-basins will 

 then get narrower and the initial phase of the future overthrust 

 sheets manifests itself on the surface as anticlinal and synclinal 

 undulations in the direction of the Vorland. 



Relation of volcnnism to crustal movements. 



The relation between eruptive activity and violent movement in 

 the earth's ciust, with regard to time as well as place, is a matter 

 of general knowledge; geologists only disagree as to the cause of 

 either. Volcanic outbursts constitute only one type of eruptive pheno- 

 mena that require penetiation of the earth's crust by the magma. 



In the case of folding movements the equilibrium will be restored 

 by the coincidence of displacements in the crust with the movements 

 of the molten magma. 



With regard to the most recent crustal movements in the region 

 under discussion, we assume that in the Moluccas they are connected 

 with folding at a greater depth. If tangential pressure reveals itself 

 in the formation of normal folds, the molten magma will, under 

 compression from all sides, sometimes force its way through the 

 crust with unequal strain, first of all near the tops of the anticlines, 

 where tension takes place; active volcanoes may then appear on 

 the top of the mountain chain (in our case the row of islands). 

 The same holds good also for oblique folds, for the time the strata 

 adhere to each other; it is evident, however, that for several reasons 

 during the folding process the independent movement of the volcanic 

 magma can be prevented, tor example when fan-shaped folds are 

 fornied that blocked up a magma-reservoir. 



In case of disruption the relations are different: tlie tension in the 

 anticliniual and synclinal tops disappears or decreases and the 

 vents of the volcanic magma leading to the surface, maintained 

 by the tension, can gra<lually be stopped up. 



