260 THE INFLUENCE OF INANIMATE SUUEOUlfDINGS. 



according to my observations, occurs exclvisively, or nearly so, 

 on the east side of the island, while, on the west, the lower hiUs 

 consist of red tufa and strata of rolled pebbles ; these are but 

 rarely traversed by the Andesite core which forms isolated high 

 hUls. Thus, for instance, the summit of that tnown as ' Royoss 

 Armlimui ' (see Map. I), which 1 did not ascend, from Kubary's 

 information appears to consist of Andesite, and the black 

 colour of the peak confirms this. These difierences in the 

 geology of the country are marked by a corresponding variety 

 in the landscape. While on the western side the slope of the 

 land is generally gentle, and small islets formed of tufa lie 

 scattered on the surface of the inner reef, the eastern side is 

 everywhere much more precipitous. There, where the black 

 Andesite rock rises to any considerable height, we frequently 

 find a quite perpendicular precipice. This is apt to hang over 

 at the top, and its base, hollosved away by the surf, generally 

 slopes to a continuous bottom of the same rock ; but we no- 

 where meet with separate islets, such as are to be seen on the 

 western side. There the strata of tufa are almost horizontal, 

 with a slight dip to the west ; according to Friedrichsen's map 

 these also occur in the island of Aruangle, since, from Kubary's 

 account, the natives declare that it consists of ' Eoyoss.' Cer- 

 tainly the description I had of it in Kriangle does not agree 

 with this. However, be this as it may, so much at least is cer- 

 tain, that at a former period the tufa of the west extended 

 much farther than it now does, since a few disrupted islets of 

 tufa lie on the sui-face of the inner reef at one or two nautical 

 miles from the main island. 



At the southern end of Babelthuap the eruptive rocks are 

 combined with the limestone rocks called ' Kokeal.' Still there 

 are but a few spots where they lie directly one on the other. 1 

 myself, in fact, have never seen them in such juxtaposition ; but 

 Wieohmann states, on the strength of Kubary's observations, that 

 solid limestone lies immediately upon the black Andesite at the 

 south-east end of Babelthuap, a spot I have not visited. Simi- 

 lar examples occur, according to this observer, on two small 

 islands lying to the south of Coroere. But, irrespective of these 

 localities, the islands composed of volcanic rock and of coralline 



