174 •• ALBATRUSS" TROPICAL PACIFIC EXPEDITION. 



Some of the diminutive canons have been cut back to a height ol' 180 feet, 

 sloping very gradually inland Irom the base of the first terrace. One can 

 readily see how the formation of these caHons if extended sufficiently far 

 into the interior would soon enable the sea to cut up the limestone mass of 

 such an island as Niue into a number of columnar islands, surrounding a 

 sound or forming a pseudo lagoon in the interior of the limestone mass. 

 This incipient erosion is the first stage of disintegration of a limestone 

 plateau, the ultimate condition of which would be represented by such a laby- 

 rinth of undercut islets and islands as we find in Fulanga or at Ngillangillah 

 or Yangasa in Fiji or at Vavau, plainly showing that the so-called lagoons 

 of these atolls are not lagoons, but are sounds which owe their formation to 

 mechanical causes ver}^ different from those which have formed a lagoon 

 surrounded by low coral sand islets. There is an abundant growth of coral 

 on the fringing reef platform, usually of Pocillipores with large blocks of 

 Porites, and Millepores extending on the .sea face slope down to about twenty 

 fathoms. Lanes of sand between the coral patches begin already at ten 

 fathoms and often extend upward to the top of the reef platform. The edge 

 of the reef flat is gouged by deep indentations with from three to five or six 

 fathoms in depth. We anchored off Alofi, two fifths of a mile from the shore, 

 in twenty-four fathoms, where an extensive flat of white coral sand makes 

 out from the shore reef platform. From the outer edge of this, the slope 

 drops off rapidly. Moss figures a coast scene of Niue, showing the ele- 

 vated reef rock of the west coast.* 



' Frederick .J. Moss, Through Atolls and Islands in the Great South Sea, London, 1889, p. 46. In 

 Commodore Goodenough's Journal (p. 188) we also find an excellent account of the geology of Niue. 



