REPORT OF THE DIRECTOR I92O-2I 10/ 



The East Indian Archipelago has since been discussed by E. C. 

 Abendanon (1919, p. 562) in his paper, " Aequinoctia, an old Paleo- 

 zoic Continent." 



Abendanon takes as a starting point his own observation that 

 through the whole of central Celebes there extends a formation of 

 crystalline schists that are strongly folded and that by their east- 

 west strike indicate an oldest folding running in that direction. 

 After eliminating a number of rocks that do not belong to the gneiss 

 and crystalline schists, but originated from more recent contact 

 zones and that have led to considerable confusion, the author finds 

 that " it must be accepted that there exist in the Dutch East Indian 

 Archipelago three series of rocks which are unquestionably of similar 

 age, and which form the basis of the other geological formations." 

 He continues: " Of these, the gneiss and the mica schists are the 

 earliest member. This double series appears as large complexes, 

 principally in the north of Sumatra, the southeast of Borneo, on 

 very extensive areas in central Celebes, and in the islands of Boeroe 

 and Ceram. As in other places, it is possible to see the lowest 

 strata, viz. the gneiss formation, in this latter island and elsewhere 

 in the Archipelago, but especially and very clearly in central Celebes. 

 In its upper part, the crystalline schists seem to grade into the ' old ' 

 schists, which constitute the second essential member of the oldest 

 formations." These schists, particularly the mica schists in central 

 Celebes, occupy such an extensive surface and reach such a great 

 thickness (certainly some thousands of meters) that they can not 

 have originated from contact metamorphism, as the younger meso- 

 zoic metamorphic rocks of these regions have, but must be the result 

 of regional metamorphism of ancient date. 



Suess (v. 3, pt 3) had already mentioned, as Abendanon points 

 out, the presence of a large massif of Archean rocks with east-west 

 strike in the islands of Boeroe and Ceram. Similar rocks having 

 the same strike are recorded from the Peling-Misool islands (Suess, 

 v - 3> pt 3) and the northwestern peninsula of New Guinea. New 

 facts have led Suess to the suggestion that the territory extending 

 from Celebes to southeastern New Guinea and beyond (island 

 Rossel) may be a geological entity and Abendanon has fully verified 

 this hypothesis by finding the east- west strike repeated "in a very- 

 remarkable way in the schists and gneiss formations " of central 

 Celebes, " although the older ranges of central Celebes and Ceram 

 have a northwest to southeast direction, owing to the post-Lutesian 

 folding." 



From these facts Abendanon arrives at the important conclusion 



