810 



b. In the thick tuff-formation along the Saadangriver (South part 

 of Central Celebes) may he distinguished according to Abkndanon ') : 



trachyte- and andesite-tntfs, 



basalt- and leucitetephi-ite tuffs, lencite-basalt, leucitite and ieucile- 

 tephrite breccias, 



trachyte-, andesife-, and liparitetuffs. 



Abendanon") takes this tuff formation to be of old-eocene age i.e. 

 younger than the old-eocene sandstone- and shale series of Pasar 

 Kira and older than the lutetien-liniestone. It is not certain though, 

 whether this formation, as a whole, is posterior to the sandstone- 

 and shale-series ; maybe there are also pre-tertiary rocks among 

 them. Van Waterschoot van der Gracht*) reports that the eruptions 

 in the West seem to have been anterior to those in the East and 

 that the age of' the volcanic series varies from the lower, anyhow 

 the middle eocene to probably the miocene. The lowermost banks 

 are still eocene as proved by nummulites occurring by the side of 

 globigerines in the matrix and inclusions. 



In the district east of the Latimodjong mountain range, where 

 numerous varieties of andesites and mostly silicified andesitic tuffs 

 occur, the oldest eruptions are deemed to be pre-tertiary, while the 

 youngest seem to have stopped before the neogeiie. Beside eruptions 

 of andesite others of liparite, trachyte, and dacite also occur *). 



As to the age of the igneous rocks of South Celebes opinions 

 differed very much up to very recently. Von Steiger ') gave us a 

 general view of the various opinions, to which we shall refer the 

 reader. 



That also here in the eocene, and perhaps prior to it, eruptions 

 took place, is borne out by the occurrence of a silicified plagioclase- 

 orthoclase tuff at the bottom of the limestone formation of the coal- 

 field Tondong Kurah') and by the andesite tuffs below the limestone 

 near Kantisang, as described by Bucking "). The majority of the 



1) E. G. Abendanon. Celebes in of uit de Tethys? Tijdschr. Kon. Ned. Aardr. 

 Gen. 1915. p. 358 seqq. 



2) lb. Geologische en Geographische enz. 1. c. p. 222. 

 ») W. A. J. M. VAN W. V. D. Gr. 1. c. 



*) E. G. Abendanon. Geologische etc. 1. c. p. 59, 60. 



*) H. VON. Steiger. Petrographische beschrijving van eenige gesteenten uit de 

 onderafdeeling Pangkadjene en bet landschap Tanette van het gouvernement Celebes 

 en onderhoorigheden. Jaarb. v. h Mijnw. 1913. pag. 171 seqq. 



6) Id. p. 217. 



") H. Bucking. Beitrage zur Geologie von Celebes. Samml. des Geol. Reichsmus. 

 in Leiden Vil. Heft 1. pag 124. 



