HAO. 115 



We then came upon a stretch with eleven islands,^ nearly all equidistant, 

 separated by shingle bars abutting on the lagoon face, upon sand bars or 

 sand islets, running like the islands diagonally across the reef flat. After 

 passing this stretch of comparatively small islands, many of the islands 

 on the reef flat became larger (PI. 67, fig. 4), the land rim consisting of a 

 series of islands of various sizes, alternating with sand bars for short dis- 

 tances. Here and there the ledge of beach rock and of recent conglomerate 

 was continuous on the sea face of the reef flat, forming a wall effectively 

 shutting out the sea from the interior of the lagoon (PI. 67, figs. 3, 4). 



On the sea face of many of the islands on the western face of Hao the 

 old ledge cropped out here and there, like low buttresses, through the mass 

 of beach rock and recent conglomerate which covered the underlying ledge 

 near the base of the shingle beach, or through the coral rubble on the inner 

 part of the reef platform. Some of the shingle beaches must have been 

 from ten to twelve feet high (PL 67, fig. 4). The islands on the eastern 

 face of the atoll, as seen from the western face, were all edged by a coral 

 sand beach on the lagoon face. 



The east face of Hao, with the exception of a stretch covered with islets 

 and sand bars to the south of the central part of the land rim, consists of a 

 few long islands. If we compare this with the condition of the west face 

 of Hao, we find that those reaches of the land rim which are raked by the 

 prevailing winds are composed of longer and more continuous islands than 

 the faces of the atoll against which the trades butt, where the land rim is 

 broken up into islets and sand bars extending across the broad reef flat. 

 The position of these islets is more or less unstable ; they migrate much 

 like sand dunes until they become fixed by vegetation, while the larger 

 islands raked by the trades are more stationar}^, the beaches of their faces 

 receiving accessions from the breaking up of the material thrown up on the 

 flanks of the land rim, — material which is in its turn carried seaward or 

 lagoonward in a direction in general parallel to the trend of the land rim, 

 while on the exposed face the tendency of the action of the sea is to widen 

 the reef flat, the material being driven towards the interior of the lagoon. 



1 Oil the cliart of Hao the difference between bare sand bars and islets covered with vegetation is not 

 indicated. 



