224 A VOLCANIC BELT 



Plutonic rocks are found in several places in both the great 

 geological divisions of the island, and also many outflows of 

 volcanic rocks, of a much more recent date. 



We have already spoken of the two principal groups of 

 extinct craters which exist in the central portion of Madagascar. 

 In the more southerly of these groups, Dr Mullens speaks of an 

 ascent of Ivoko, one of the finest old volcanoes, which is eleven 

 hundred and thirty feet high. This, he says, " was a vast 

 crater, a quarter of a mile across ; the encircling wall was 

 complete except at the south, where the opening was fifty feet 

 wide. Beneath us, half-a-mile to the east, was another crater, 

 latsifitra, second only to Ivdko, with its opening to the north. 

 On the north-west shoulder of Ivdko were two other large 

 craters, overhanging the village of Betafo, two more were 

 close by to the north-east, and others were conspicuous ten 

 miles to the north. On the south again were several others, 

 the horseshoe shape being very marked in them all. Descend- 

 ing to the crater of latsifitra, we observed that the lava rocks 

 which had issued from it were black, sharp and fresh, as if they 

 had been broken yesterday. On the plain I counted thirty 

 greater piles of lava, like ruined fortresses, and numberless 

 smaller ones. It was clear that like the Phlegraean fields in 

 Italy, the entire plain had at some time been on fire ; and that 

 a hundred jets of flame and molten lava had spurted from its 

 surface, hurling their blazing rockets into the sky. Altogether, 

 in our journey to the west and south-west of the capital, we 

 counted a hundred extinct craters, extending over an arc of 

 ninety miles." 



Madagascar appears, therefore, to be the extinct central 

 portion of a volcanic belt which extends from Great Comoro 

 to the north-west, through the other islands of the group, 

 N6sibe and northern and central Madagascar, to Reunion to 

 the east, a distance of thirteen hundred and sixty miles. And 

 it is noteworthy that at each extremity of this belt there is a 

 still active volcano viz. Piton de Fournaise, in Reunion, and 

 one eighty-five hundred feet high in Great Comoro. 



As a country showing numerous traces of volcanic disturb- 

 ance, Madagascar is almost every year visited by shocks of 

 earthquake. Happily these are not of a severe character, 

 and little damage is usually done ; although often a strange 



