AEQUINOCTIA, AN OLD PALEOZOIC CONTINENT 565 



side. The real gneiss must be separated from the gneissoid rocks 

 which originated at the periphery of the younger granites at the 

 time of their soHdification. These gneissoid rocks appear in large 

 quantity in Central Celebes, and Volz believes he has detected 

 them in the north of Sumatra. As to the crystalline schists, it is 

 advisable to distinguish the old mica schists from the rocks belong- 

 ing to the more recent contact zones, as for instance the andalusite 

 mica schist from Central Celebes. Finally, there is no doubt that 

 there has been included with the ''old" schists rocks' which do not 

 belong to them. For instance, in his Rapport sur les Moluques 

 (P- 755)) Verbeek places the argillaceous schists of the island of 

 Taliabo in the old schists formation. However, they recall so 

 much certain schists of the Upper Cretaceous, either metamor- 

 phosed or not by the granite of the southwestern part of Central 

 Celebes, that I can no longer consider them as being undoubtedly 

 old schists. 



Having eliminated the rocks which do not belong to them, it 

 must be accepted that there • exists in the Dutch East Indian 

 Archipelago three series of rocks which are unquestionably of 

 similar age, and which form the base of the other geological 

 formations. Of these, the gneiss and 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 archi- 

 pelago, but especially and very clearly in Central Celebes. In its 

 upper part, these crystalline schists seem to grade into the "old" 

 schists, which constitute the second essential member of the oldest 

 formations. These schists are well known in many parts of the 

 archipelago, but only Volz has pointed out their conformability 

 with the mica schists in the north of Sumatra. 



Particularly in Central Celebes the mica schists occupy such an 

 extensive surface, vertically as well as horizontally, that there is 



' Tobler (and before him Wing Easton and Volz) had already called attention to 

 this point; however, he does not exclude them systematically from the denomination 

 "old schists." 



