ch. i LEADING PHYSICAL FEATURES 5 



range, composed mainly of grey olivine-basalts, which is not 

 indicated in the profile. 



The two conical peaks of Vatu Kaisia (1,880 feet) and Na Raro 

 (2,420 feet), which rise up so unexpectedly in the region imme- 

 diately east of the Ndrandramea district, are also of acid andesitic 

 rocks, in the last case approaching the dacitic type. They lie 

 within the borders of the area of basic tuffs, basic agglomerates, 

 and basic massive rocks, that here begins and extends eastward 

 to Mount Thurston and a little beyond. East of Na Raro there 

 is a gap or break in the profile, where the greatest elevation is 

 probably not over 800 feet ; and on its farther side rises up the 

 mountain of Va Lili (2,930 feet), a lofty inland ridge that lies 

 towards the southern coast. Palagonite-tuffs and agglomerates are 

 the prevailing surface-formations in this district. 



Eastwards from Va Lili extends for eight or nine miles a lofty, 

 level-topped, and almost peakless range, which I have called the 

 Korotini Table-land, after the towns once situated on its southern 

 slopes. Its outline is shown in the background of the view facing 

 page 153. It is, however, not so level-topped as it appears to be; 

 but the gradual variations in elevation between 2,000 and 3,000 feet, 

 when spread over a length of some miles, are more or less lost in 

 the general outline of the range as viewed from the coast. Basic 

 agglomerates are principally exposed on the lower slopes ; whilst 

 higher up, reaching often to the summit of the table-land, occur 

 palagonite-tuffs containing tests of foraminifera and molluscan 

 shells, massive basic rocks being exposed in places. 



The level profile of the Korotini tableland gives place, as one 

 proceeds eastward, to the broken outline of the several lofty peaks 

 of Mariko (2,890 feet), Mbatini (3,437 feet), Thambeyu (3,124 feet) 

 and others. 1 Each of these peaks marks one of the bold 

 mountain-ridges that form such a striking feature in the surface- 

 configuration of this part of the island. On the slopes of these 

 ridges, and often also on their summits, appear basic agglomerates 

 and palagonitic tuffs and clays often inclosing tests of foraminifera ; 

 whilst exposed in the gorgesand protruding at times through the tuffs 

 and agglomerates on the crests of the ridges are displayed massive 

 basic rocks of the type of the hypersthene-augite andesites. 



East of Thambeyu the level sinks to about 1,000 feet above 



1 Mariko is the native name ot the Drayton Peak of the chart. Mbatini 

 is the correct name for the Koro Mbasanga of the chart, the true Koro 

 Mbasanga lying three miles to the north. Thambeyu is a native name for the 

 Mount Thurston Range. 



