100 APPENDIX I. 



between the extreme ends of the islands. In width it is coinpiuul)le to that of the ocean phitform from 

 the breccia sheet to its extreme ocean margin on the majority of those ishinds with an eastern aspect. In 

 like manner Ijetween these limits its water-channels and general reef characters are similar. The corrosion 

 zone corresponds with that of a normal corrosion zone until the east end of Telele is approached (p. 102). 

 These three islands, like those which we have jnst seen on the S.W. portion of the atoll, and more clearly 

 like the other eastern islands, rest on a portion of the sheet on both the ocean and lagoon sides. On the 

 lagoon side we have just seen its eroded thinned-out edges in the so-called " headlands " rising np to more 

 or less near high-water level, .sometimes over, though occasionally much less. This breccia sheet again 

 rests on the HcUopora platform (O.L.I). 



MOTULOA. 



At this island, after the corrosion zone, we find a .slope more or less steep, extending from 10 to 

 50 feet, in which the rise of the incline may vary from 1 up to -1 feet, and, where the incline is not great, 

 cliffs occur reaching to the top of the breccia sheet, foiming a series of buttresses, which are here also, as 

 at other eastern islands, about 1 foot to 1 foot 6 inches above high water. The top of this cliff is then 

 generally clear of hurricane-borne material for a short distance, varying from a foot to a few yards, after 

 which the Hurricane Bank begins. This, along Motuloa, is nowhere very high, l)ut in a few places it is 

 from 5 to G feet above high water, though this is not moie than 2 or 3 feet above the general surface of 

 the island. Tlie name signifies Long Island (Motu, island — Loa, long.) 



Near the western commencement of Motuloa, and adjoining the wide l)reach, the breccia sheet has, 

 like that in the breach, been eroded much farther 1)ack than the general outer line of the mass along the 

 ocean side to near Motusaiiapa. Thus the island also has been eroded back for a considerable distance 

 at and near the S.W. point, the trees and shrubs being undermined and falling on the breccia platform. 

 Here the Huiricane Bank has altogether disappeared with its foundation. The breccia sheet also has in a 

 few places been ei-oded back to nnich ncai'er the Hurricane Bank than at others, thus greatly reducing 

 the defence, and forming a niorf or less concave outline. Here the sea has made a course for itself across 

 the island; at first only the liigli storm waves found a tiack among the trees, l)ut this became more and 

 more worn till a channel was formed. These lireaches occui' in all stages of development, and in nearly all 

 directions ; some cut straight thiough the island, another appears to ha^e met with some obstruction in 

 its direct cour.se, or has found an easier track, and has taken an oblic^ue direction; while, near its 

 eastern end, some obstruction (here, apparently, the trees) has prevented the formation of a suflScient 

 direct outlet, and the stream has forced an additional one for itself along the centre of the island, which 

 here is composed of the finer fragniental mateiial to a lower depth than usual. The breach then takes a 

 curve out intcj the lagoon through the nearest of the breaches at Motusanapa ; along this course the 

 1)ank of sand and small shells is l)eing eroded, and shrubs are falling. 



On examining these channels the l)reccia was seen to have Ijeen eroded or dissolved in .some jjlaces 

 below tlie original level of the sheet, and to liave been subsequently levelled up with the general material of 

 which the ocean side of the island was then composed. That contains no pumice, none of which was 

 observed at the lower levels of the island mass. This was, I think, beyond doubt in these places caused 

 by erosion from the lagoon side before the present material covered it (see Section I, Motuloa (Plate 5) 

 as an example, and possibly also Section HI). I am of opinion, however, that solution, which is still 

 proceeding, though in a comparatively small way, in portions of this island, has, at an earlier period in 

 its history, had also more oi' less to do with this ; since, apart from Iliu-ricane Banks, accumulation is 

 proceeding only at two sand banks on the lagoon side of the island, one neai- and at each end ; in all 

 other places it is undoubtedly l)eing eroded. 



