292 A DIFFICULT PROBLEM 



descent to the level western plains is gradual ; so that a railway 

 to the north-west ports, along the valleys of the Ikopa and 

 Betsibdka rivers, would, although longer, present very much 

 less engineering difficulty than that from Tamatave to the 

 capital. 



On Saturday morning we came to the bank of the Ikopa, 

 which river is at some points half -a -mile or more wide, but then 

 at its lowest level, being apparently very shallow, but so inter- 

 rupted everywhere with shelves of rock that it would be 

 difficult for even a small canoe to make its way far. There 

 were numerous islands, covered with bamboo, bararata, rojia- 

 palms and other vegetation. From a low hill we had a view 

 over an immense expanse of flat country on the western side 

 of the river. Only here and there was the level broken by a 

 line of hills of small elevation. After leaving the Ikopa we 

 found ourselves in a very different kind of country from any 

 we had yet passed through, a succession of low hills or mamelons 

 of dry sandy gravel, with hardly any vegetation, and looking 

 as if no rain had fallen upon it for years. In the afternoon I 

 noticed that a large number of granite boulders were strewn 

 over the country, and could hardly doubt that these, from their 

 rounded forms, but especially from the absence, as far as I 

 could see, of any such rock in situ, must by some means or 

 other have been transported from the granitic region of the 

 interior far to the eastward. Must this not have been glacier 

 or iceberg action ? Although it is difficult to understand such 

 agency in the tropics. 



Ten years after making the journey, my friend, Mr Baron, in 

 travelling across the island towards the north-west coast, but 

 about a hundred and twenty miles farther north, came across 

 isolated rocks, which were quite different in composition from 

 anything near them. Of these he said : "I could think of no 

 agent to account for their occurrence but that of glacial action. 

 They seemed to me to be perched blocks, as there was no hill 

 near from which they could have fallen, nor any rock of the kind 

 in situ." I was interested to find that an expert in Madagascar 

 geology like Mr Baron had come to the same conclusion as 

 myself with regard to these granite boulders. 



Early in the afternoon we arrived at Mevatanana, the most 

 important place in this part of the country, with about a hun- 



