Geology. — “On the Crustal Movements in the region of the curving 
rows of Islands in the Kastern part of the East-Indian 
Archipelago”. By Prof. H. A. Brouwer. (Communicated by 
Prof. G. A. F. MOrLENGRAAFF). 
(Communicated at the meeting of November 25, 1916). 
Of late years various explorers *) have pointed out a resemblance 
in the tectonic structure of the curving rows of islands of the 
Moluccas and that of many curving chains of Alpine structure. Large 
overthrusts formed down to the miocene, have been discovered in 
various islands and the zone, characterised by overthrusts, is bordered 
on the outside by a region, in which the mesozoic and tertiary 
deposits are slightly or more intensely folded, but no overthrusts 
occur. Actual facts seem to indicate that in the curving rows of 
islands of the Moluceas may be distinguished : 
1. A zone characterised by overthrusts (Timor-Ceram row of 
islands). 
2. A marginal zone without overthrust-tectonie (Sula-islands— 
Misool, Western New Guinea south of the Mac Cluer bay and probably 
also the Kei-islands). 
3. An inner zone with the young active volcanoes. 
4. A zone lying between 1 and 2 of older voleanic rocks (North 
coast of Netherlands-Timor, Wetter, Ambon, peninsula of Huamual 
in South-Western Ceram and Amblau). 
We will now pass in review the features of these zones. 
General situation and origin. 
If the sea-level in the East-Indian archipelago were to subside 200 
m., Sumatra, Java and Borneo would form one mass of land with 
the peninsula of Cambodja and Siam, just as Australia with the 
Aru-islands, the vast tract now occupied by the shallow Arafura-sea 
G. A. F. MoLENGRAAFF. Folded mountain chains, overthrust sheets and block- 
faulted mountains in the Hast Indian Archipelago. Compte Rendu du Xlle congrès 
géol. internat. Toronto 1913, p. 689. 
H. A. Brouwer. On the Tectonics of the Eastern Moluccas. Proc. Kon. Ak. 
v. W. Amsterdam. Vol. XIX. N® 2, p. 242—248. 
