26 BULLETIN : MUSEUM OF COMPARATIVE ZOOLOGY. 



exceeded -i feet vertically or laterally. Other islands furnish equally 

 good examples of this modern erosion, but only in cases where the 

 cliffs faced a wide expanse of lagoon or sea, with no intermediate reef. 1 

 South of Thithia a remarkable mass of volcanic agglomerate occurs 

 that exhibits similar weathering, inducing thereby a toadstool shape in 

 the block. 2 Fine erosion effects are visible on the great outlines of the 

 Mango cliffs, which have been carved into the most bizarre possible 

 forms. Equally curious also are some of the under-cut cliff-bases at 

 Fulanga, 8 where islands filling the lagoon of the raised reef exhibit every 

 stage in this undermining of the cliffs. Besides the islands just enu- 

 merated, Vatu Leile, 4 Naitamba, and Kambara show equally striking 

 results due to erosion. In some cases the redeposition of carbonate of 

 lime has taken place to such an extent as to almost obliterate the traces 

 of the erosion-line (Plates 28. 30, 31). Much iron as ferric oxide is 

 mixed with the redeposited lime material, and imparts a rich-brown or 

 red color to the mass. 



At Vatu Leile this redeposition of calcareous material charged with 

 ferric oxide has gone on very largely in the line of erosion known as 

 " The Great Walk," parts of which it has completely obliterated, while 

 other parts are half filled with large masses of the deposit. At the 

 southern extremity of Vanua Mbalavu, another line of beach erosion 

 occurs tilted at 15° to the horizon. Here again the cliff has almost 

 regained its original shape by subsequent refilling of the wave-worn 

 groove. 



Most of the islands, as Thithia, Lakemba, Taviuni, Vanua Mbalavu, 

 Vatu Vara, Kambara, and Vatu Leile, have more or less well developed 

 flats extending along the bases of the hills, whether volcanic or lime- 

 stone. The Mango flats vary from 100 to 250 yards in width, and 

 throughout this extent are fairly level. They are most persistent along 

 the windward or southern side. Two flats were examined, one on the 

 south and one on the northeast of the island. In both cases they lay at 

 the bases of limestone cliffs 400 and 500 feet in height. The seaward 

 edge of the flats is perhaps higher than the middle portion. To make 

 sure of the origin of this raised portion, two holes were sunk till the 

 harder basal rock was reached. In both cases the old beach rock was 

 found, and this at a distance of nearly 200 yards back from the present 

 similar formation. 



1 See A. Agassiz, I. c, Plate 94 (Ongea). 



2 See A. Agassiz, I. c, Plate 62. 



8 See A. Agassiz, /. c, Plates 82, 83, 84. 

 4 See A. Agassiz, /. c, Plates 9G, 100. 102. 



