443 
of the soil and the sedimentation was still in progress. The belt G, 
generally has been upheaved, folded and compressed to a stronger 
degree than the belt G,. 
The folding of the belt G, is not seldom accompanied by voleanic 
activity causing the sediments in this area to be for the greater 
part composed of voleanic material. This area G, might, in contra- 
distinction to Z, also be called the secondary area of denudation. 
$$ eee 
L Continental 
Area of denudation 
EE ET et Se a 
G Coal and 
Geosynclinal Petroleum 
coastal belt 
G A EEE ee TEE VTi ed 
Folded mountain 
chains, often 
Area of Sedimentation G, F vol 
seat of volcanic 
activity 
ET I EN A ea cl al a a 
Fig. 1. 
Our object in writing this paper is to discuss how far the position 
of the oil-fields of the Dutch East-Indies, fits in with the scheme 
sketched above. 
The location of these oil-fields is marked on the accompany ing 
sketchmap') (Fig. 2). They are situated along the north-east coast of 
Sumatra, along the north coast of Java and along the east coast of 
Borneo. The sediments of which those oil-fields consist, have been 
deposited in the geosynclines in Tertiary, especially in Neogene time. 
1) In compiling this sketchmap two authorities on the Australasian oil-fields 
Kein and Rurren kindly have procured me some valuable data. 
29 
Proceedings Royal Acad. Amsterdam. Vol. XXIII. 
