26 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
exceeded 4 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. 
South of Thithia a remarkable mass of volcanic agglomerate occurs 
that exhibits similar weathering, inducing thereby a toadstool shape in 
the block. 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,® 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,t 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° tothe 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, /. c., Plate 94 (Ongea). 
2 See A. Agassiz, /. c., Plate 62. 
8 
4 
See A. Agassiz, /. c., Plates 82, 83, 84. 
See A. Agassiz, /. c., Plates 96, 100. 102. 
