AEQUINOCTIA, AN OLD PALEOZOIC CONTINENT 



E. C. ABENDANON 



Wassenaar, Holland 



Through the whole of Central Celebes/ from the Gulf of Boni 

 to the Gulf of Tomini, extends a formation of crystalline schists, 

 lying east, but principally west, of Lake Pqsso. These schists are 

 strongly folded and their positions vary from horizontal to vertical. 

 More than once, but last during the Oligocene, this region was 

 leveled by denudation. The resulting peneplain was arched 

 during the neo-Tertiary and Plio-Pleistocene to 2,000 meters above 

 sea-level. Consequently, it became deeply cut by erosion. In 

 some of these furrows one can distinctly observe an east-west strike 

 of the strata, which seems to be the effect of the oldest folding. 

 Especially on the west of Lake Posso the region appears now as a 

 distinct geographical entity. West of these mounts others follow, 

 either separated from the first by depressions or not. They consist 

 of gneiss, viz., biotite and amphibole gneiss, amphibolites, granites, 

 and effusive rocks. In this part of the country the peneplain 

 character has not been preserved so well; the highest tops reach 

 altitudes up to 3,000 meters. 



In no other part of the Dutch East Indian Archipelago do the 

 gneiss and schists region occupy such a large surface as in Central 

 Celebes; besides that, the crystalline schists are characterized by 

 a particular richness of rock varieties. 



Most of the schists belong to the second and eighth groups of 

 the Grubenmann^ classification, and to the upper and middle zones 

 of these groups. This leads to the conclusion that they represent 

 metamorphosed clays, sandstones, and argillaceous sandstones. 

 Besides these rocks, a certain importance must be attributed to the 

 metamorphosed calcareous sandstones and limestones, rocks of the 



' See E. C. Abendanon, Voyages geologiques et geograpkiques a travers la Celebes 

 Centrale, 3 volumes and one atlas, Leyde, Holland, 1916-18. 

 ^ U. Grubenmann, Die kristallinen Schiefer, Vol. II, 1907. 



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