( 226 ) 



from the soiitli-side, fliis mountain lies to the right of the Walèlang 

 (= WaHraiig). Only the greater western part is to he seen, but the 

 missing eastern part corresponds almost witii the other extremitv. The 

 shape reminds of that of the hill in the huge recent crater of Oena-Oena 

 (Toraini-bay) said to have arisen during the eruption of 1898 ; 

 (Verslag over de Geol. en Mijnbouwkundige onderzoekingen in de 

 residentie Menado van het jaar 1900, Jaarl). v. h. Mijnwezen in N. Indie, 

 30^"-' jaarg. 1901 page 118). Probably the central monticule, which 

 in Oena-Oena is covered like the surrounding crater-landscape with 

 masses of sand, at the Sempoe with gravel, is in both instances a mass 

 that has moved outward, something like what was formed in 1904 in 

 the crater of the volcano-island of Roeang (1. c. 38''' year 1909 page 222 

 v.v.) and has l)een stated already to have occurretl also in the 

 immediate neighbourhood of Sempoe in the Sopoetan-eruption of 

 1906. With such a mode of formation both at Sempoe and at Oena- 

 Oena the opening through which the mass has emerged must lie 

 directly below the highest pai-t of the to|>, in this respect differing 

 from what occurred at Roeang, where the emei-ging mass very soon 

 iilled the whole crater-cup. 



Both sommas, as reconstructed on the map as far as |)Ossible 

 from the present course of the walls, extend for a short distance 

 over each other to a maximal breadth of about 150 M. Since these 

 craters have come to rest they must have widened however by the 

 tumbling down of their walls, which consist, as far as can be seen, 

 of a tufaceous mass, decomposed, whitened and softened by acid 

 vapours. 



This receding of the walls however cannot have been of great 

 amount, as appears clearly from the l)oun(laries of what still Jiow 

 can be recognized as true crater-bottom, indicated on the map by 

 thinner stri|)ed lines. The walls of the solfatare Walclang teach us 

 that there the old bottom of the crater does not consist of eruptive 

 gravel, or only to a slight depth, and consequently at the end of 

 the activity it did mtt lie lower than at the present moment, so 

 that this period cannot be so long gone by. 



These considerations, for which on the map abstraction should 

 be taken of the solfatare Walèlang and the surrounding inflection 

 of the level lines, probal)ly dating not farther back than the beginning 

 of the 19''' century, may account both for the nose-sIia|)ed spurs 

 projecting from the mountain-walls into the common zone of the 

 bi-circular system and for the somewhat vague features of the relief 

 in the middle part of this zone. 



From the fact that of the two crater-walls, in so far as they 



