AGASSIZ: FIJI ISLANDS AND COEAL EEEFS. 65 



elevated to nearly three hundred feet, and it has been subject for a long 

 period to the action of the atmosphere and of the sea ; the one wearing 

 down the limestone land into an inner basin or cutting it out into 

 valleys, and finally into islands and islets ; the other encroaching into it 

 from the outside, and eventually forming an interior basin studded with 

 islets, which to all appearance would be a lagoon surrounded by an 

 encircling reef with its heads and patches and islands and islets. And 

 yet it would really be a crater-like basin, a " Sound," which by erosion 

 had become connected with the true bari-ier reef lagoon, and finally even 

 all trace of the Sound character of the inner basin might vanish with 

 the disappearance of the old shore line, and the existence of only islets 

 to indicate tlie former land area. 



In the case of Fulanga, Gardiner -^ has well described the action of the 

 sea both as a solvent and as a disintegrating factor in reducing the rocks 

 and islets to mushroom-shaped structures, and in the great undercutting 

 of the cliffs, of which he gives the same illustration as that I give here, 

 which was kindly furnished me by the Hon. W. L. Allardyce. He says : 

 "The final result should be a perfect atoll reef just awash, the laud be- 

 ing dissolved away while the living reef round it continues to grow." 

 So it does, but the reef has played no part in the shaping of the atoll, 

 the lagoon of which owes its existence to the formation of the interior 

 Sound by the decomposition of the elevated tertiary limestone reef mass, 

 and has no connection with the recent coral reef growing upon the reef 

 flats or external platforn:t of submarine erosion. 



%?;m?aaa^n%'t~— ■-■-g-- -- ■ 



SOUTHEAST POINT OF MARAMBO. 



Marambo. 



Plate '-i3. 



Marambo is a small circular island about three quarters of a mile in 

 diameter (Plate 22). It is composed of elevated limestone rising to 

 160 feet in height. It is surrounded by a fringing reef fully a mile ia 



1 Loc. cit., p. 459. 



VOL. XXXIII. 5 



