Geology. — "O/i tke N on-exisience of Active Volcanoes between 

 Pantar and Dammer {Ëast-bidian archipelago), in Connection 

 until the I'ectonic Movements in this Ref/ion". By Prof. H. A. 

 Bhouwkr. (Communicated by Prof. G. A. ¥. Molengraaff). 



(Communicated in the meeting of January 27, 1917.) 



It is a striking phenomenon tliat active volcanoes occur in all 

 the islands of the Sunda-range Sumatra-Java-Bali-Lombok-Sumbawa- 

 Flores-Lomblen-Pantar and do not exist farther on to the east in 

 Alor, Kambing, Wetter and Roma, but reappear still farther east- 

 wards in the curving chain of volcanic islands Dammer Teon-Nila- 

 Serua-Manuk-Banda. 



According to Vkkbukk ^) the volcanoes of the Banda Sea form an 

 ellipse separated from the volcanic Sunda islands by the "strip of 

 older rocks", drawn by him across Wetter. In a paper on the 

 recent mountain-building movements in this region ') we have 

 designated the arch of volcanic islands in the Banda Sea, for the 

 most part situated below the sea surface of the sea, as a continua- 

 tion of the range of the Sunda islands. On this basis the non- 

 existence of volcanoes in a certain portion of this chain must be 

 accounted for as a phenomenon resulting from causes of a more 

 general nature. 



We enumerate, with reference to the volcanic phenomena, the 

 following characteristics of the two curving rows of islands in the 

 eastern part of the Indian archipelago. 



a. The outer row (Timor-Tenimber-Ceram-Buru) is entirely devoid 

 of volcanoes. These are to be found only in the inner row (Flores- 

 Wetter-Dammer- Banda). 



b. Occasionally the active volcanoes are also missing in the inner 

 row, just where the two rows approach each other most, i. e. to the 

 North of Timor (see Fig. 1). 



^) R. D. M. Verbeek. Molukkenverslag Jb. v. hel Mijnwezen 1908 Wet. Ged. 

 Kaart W. i. 



') H. A. Brouwer, Over de bergvormende bewegingen in het gebied der boog- 

 Torraige eilandenreeksen in het oostelijk deel van den O.-I. Archipel. Versl. Kon. 

 Ak. V. Wet.. Amst.. Nov. 1916. 



