108 B. KOTO : THE GEOLOGIC STRUCTURE OF 



as Centeno long ago pointed out, and is named the Sangi fissure 

 by Wichmann, ^^^ may be traced from the volcano Sanguil in the 

 southernmost point of Mindanao through Butulan (Sarangami), 

 G. Awu in Sangi, G. Api in Siao, submarine solfatara near 

 Bauna Wuhu,^'^ and Ruwang to the andesitic Klabat, Lokon, and 

 the basaltic Sempu, in Minahassa in North Celebes. The chain 

 with eleven volcanoes turns in a south-easterly direction, and 

 proceeds through Bolaug, Mongondo, and then Boliohutu, whence 

 it leaves the land and enters Tomini Bay. The Tongean Islands 

 and perhaps Tandjong Api,^^^ near Boss, in Central Borneo belong 

 to this long belt. 



By the way, it may be noted that in the Sangi belt, the 

 greatest among the volcanic islands is Sangi itself. It carries 

 Gunung Awu, 1500 m. high. It made eruptions in 1641, 1711, 

 1812, 1856, and so lately as 1892. Its activity is of the Asiatic 

 type. In tlie last eruption it ejected a large quantity of ashes 

 and sent down voluminous mud-streams. It was accompanied 

 by a shake over an extensive area, earthquakes being felt in 

 Makassar at a distance of 1,200 km. from Sangi, and even on 

 the coast of Floris, where they were followed by sea-waves.^^^ 



As I have said, the meridional ridge of Celebes runs along 

 the whole west coast, the axis of these mountains being built 

 up of crystalline schist, tourmaline-quartzite, and glaucophane- 

 schist®^^ penetrated and overflowed by andésite and basalt. The 

 whole complex is flanked with tufts which make a fertile plain 

 along the Strait of Makassar. This in turn is overlaid by the 



56) Zeitschr. d. deutsch, f/eo!. Gc:<eU., Jahrg. 189o, p. 540. 



57) "SViclimann, Nattturhunduj Tijdschrift voor Ned. Indie, Dl. LVII, 1897, p. 220. 



58) P. u. F. Sarasin, ZeUschr. d. Gesell, f. ErdL-unde. z. Berlin, Bd. ;!0, 1895, S. 350. 



59) Wichmann, Zeitschr. d. deutsch. Geol. Gefidl., 189^, S. 545. 



60) Wichmann, iVgues Jahrbuch f. Mineralogie, etc., 189;l, Bd. II, S. 176. 



