FAKAEAVA. 77 



such that additional islands are formed on the inner face of the lagoon 

 from the deposition of drifting material, we should have (supposing that the 

 reef flat has been gouged out to a moderate depth by the action of the sea) 

 a secondary lagoon, comparatively narrow, formed between the lagoon face 

 of the flat and the interior line of islands thrown up more or less pai'allel 

 to the inner lagoon face of the land rim. 



When off the north end of Fakarava it appears like a long continuous 

 island with the usual fringe of low bushes and shrubs sheltering the cocoa- 

 nut palms. On the western side of the lagoon there are many islets, but 

 few rocks and ledges are exposed at low-water mark on the eastern side 

 of the north passage, and the. same condition continues southward along 

 the eastern lagoon face. 



On the north side of the entrance of Fakarava — Ngarue Pass (PI. 46, 

 fig. 2), which is half a mile wide — the old ledge crops out in places, and 

 there is a long bare point on the south side of the entrance. In the pass 

 there is from 5 to 7 fathoms of water, and once inside the lagoon the slope 

 drops rapidly into 17 to 19 fathoms (PI. 204, fig. 1). On the way to the 

 anchorage off Rotoava we passed several outcrops of the old ledge (PI. 47, 

 fig. 2), indicated as shoals on the charts. Two are three and even five feet 

 above high-water mark (PI. 58, fig. 1). Several flats make out as spits from 

 the land rim on the lagoon side, showing the former lagoonward extension of 

 the land. The shore line of this atoll has gradually been shifted and changed 

 by erosion and disintegration and solution into the lagoon flats and shoals. 

 All of these are generally composed of old ledge rock planed down from 

 various causes to their present level. 



The old ledge crops out on the sea face at several points, and is seen to 

 run out from the top of the beach in wide buttresses upon the reef platform 

 at right angles to the general trend of the surf. At other points the surf 

 has cut down the old ledge to the level of the reef platform, or the sand 

 and shingle forming the sea beach have overwhelmed the remaining low 

 buttresses and concealed their presence (PI. 51, fig. 2). 



In the lagoon the sea breaks with considerable force, and the outcrops of 

 the old ledge are separated by sand reaches, or even by short stretches of 

 recent beach rock (PI. 49). There are in the lagoon a great many ledges, 



