( 228 ) 



liokl, in tlie Sopoetan inoiuilaiiis it is undoubtedly confirmed. What 

 I saw in the Minahassa strongly impressed me tliat iliere is a 

 cei'tain contrast between these andesitic igneous rocks and tiie light 

 pumice-tufa, and at least for I he stratified tufa it is clear that its 

 deposition belongs to a now-closed period. Hence on good grounds 

 we may conclude that Sopoetan proper has nothing to do with the 

 deposition of these beds of tufa. In how far that external contrast 

 answers to more essential petrographic and chemical differences and 

 if perhaps other volcanoes of the Minahassa may thus be shut out, 

 these questions 1 must leave now undiscussed, the data of our Menado 

 exploration still awaiting their final composition and for the present 

 not l)eing at my disposal. 



If for \alid reasons the conception of the Tondano-plateau with 

 its comb-shaped eastern margin and the adjacent tufa-layers dip[)ing 

 and slicl\ing towards the sea as a gigantic volcano, might iji the 

 end prove to be untenable, as I am inclined to believe, it will not 

 l)e difficult to find any othei' of the neighboiii'ing eruptive scats apt 

 to be held res[)()nsible for these tufa-deposits. 



On the southern flanks «»f the |»lateau it is (lillerenl. The tida- 

 layers occur here in ground that belongs unmisiakaitly to llKM-nninion 

 volcano-foot of the group Sopoetan-Mauinipoidk. So their presence has 

 here the demonstrative power that we mu^t as yet deny to those 

 of the just-mentioned Lendiean-chain. ( )nce indiu'cd to conclude 

 that the older volcanoes of that ,iirou|> have given vent to the 

 material for the puniicc-liira, in so far as this forms tlieji- own 

 mantle, we may readily jidmit that the eruptions from these large 

 craters ha\e also s[)read the pumice-tufa to a «•reat distance in the 

 surrounding country. If it is confirmed that the circular walls and 

 bottom of the Riudengau- au<l Sempoe-craters are composed of the 

 like material, then a more direct proof is given of the paif that 

 has been assigned here to these volcanoes. 



With regard to the details of location ihere is an almost perfect 

 congruence between the solfature of 1901 ami the neighbouiing 

 Walèlang. In both cases the solfatare lies upon the channel lon.ui- 

 tudinally cut l)y the brook in the valley-flat, Walèlang on the brook 

 Masem, the solfatare of 1901 on the Pentoe. Relating to Walèlang 

 we niav remark that by some authors the name of Masem is like- 

 wise given to the solfatare: the Sakasins even spenk oï Md-si'in-crnter; 

 this must be a mistake ; the name of Afn.si^iii belongs exclusively to 

 the brook. Classing these solfatares with the craters may oidy be 

 allowed for, if the so-called explosion-craters are ranged under this 

 category. Indeed one may s})eak as well of water-volcanoes as of 



