KAMBAEA. 207 



thus formed ; that it would have precipitous sides, leading from the outer 

 rim toward the deepest parts of the basin, and not the . gentle slopes 

 characteristic of the basins of Kambara, of Mango, and of other so-called 

 elevated atollis. 



The gap to the south of Tokalau shows plainly that the sound 

 (PI. 127, fig. 2), which existed at the time when it communicated with the 

 sea, was eroded much in the same way as were the sounds of Fulanga, or 

 of Mango, or of Namuka.^ The diminutive sound formed on the southern 

 part of Ongea opens out into a valley which extends far inland towards the 

 northern extremity of the larger island of the atoll, and thus has been 

 formed an area of denudation in the interior of Ongea, very similar to 

 that of Eua, only on a much smaller scale. Similarly the topography of 

 Thithia, Tuvutha, of Wangava and other islands, clearly indicates that 

 submarine erosion, as well as solution and denudation, has been the 

 principal factor in shaping their topography, and that the lagoons of the 

 so-called elevated atolls are merely sinks, such as are common in all lime- 

 stone districts.^ 



The basin of Kambara, as seen from the top of its volcanic cone, is not 

 deep ; the greatest difference of level between the bottom of the sink and 

 the top of the volcanic hill is not more than 250 feet. The limestone rim 

 which forms the edge of that basin is of very varying height (Pis. 126; 127, 

 fig. 1) ; at some points it can hardly be more than fifty feet above the 

 level of the bottom. It is very evident that during its elevation there 

 has been connection between the sink and the sea through the lower parts 

 of the rim, or through some of the gaps which have been cut, probably at 

 a time but little antedating the present, and have given an outlet to the 

 drainage of that basin. The volcanic outburst has carried up on its sides 

 part of the limestone rim, as large masses and fragments of limestone were 

 picked up over the volcanic slopes. At the very top of the hill a calcareous 

 ridge still exists, the remnant of the edge of the limestone basin which has 

 been broken into by the volcanic outbiu-st. The bottom of the basin is per- 

 haps from 75 to 100 feet below the highest point of the calcareous rim ; it 



1 Bull. M. C. Z., XXXriI.. 1K99, Pis. 20. 22. 



"- Hill, R. T., Geology of Jamaica, PI. IX. fig. 2, Bull. M. C. Z., XXXIV., 1899. 



