224 CHALLENGER 



Group at least, are being built up gradually upon old, sinking 

 volcanoes as Darwin had proposed. As Gaskell and Swallow 

 concluded that there was 2^00 feet of coral below Nukufetau, a 

 considerably greater depth than that under Funafuti, it would 

 seem perhaps that while Funafuti still remained an island about 

 500 feet high, Nukufetau as a volcanic island had passed from the 

 face of the oceans. 



