BY E. C. ANDREWS. 155 



table of aplite occurs, traversing the ternary granite of the locality. 

 It has the appearance of a fine-grained white sandstone. Its dip 

 is about 10°, and it may be traced over an area of at least five 

 acres. 



At Challenger Bay an interesting Hat occurs joining two high 

 points of the island, which, but for its presence, would exist as 

 separate islands. 



The flat is about one and a half miles in length and 500 yards in 

 width, with an average height above H.W.M. of at least 15 feet. 



A gutter some six feet wide and ten feet deep has been 

 excavated through the centre of this flat by the forces of erosion. 

 The structure of the plain as revealed by this miniature valley is 

 a sandy clay, coarse sand, and a clay containing angular frag- 

 ments of granite. No shells or calcareous material were seen, 

 although careful search was made. 



Fig. 2. — Sketch Section across Palm Island " Katsed Plain." 



a. Mt. Bentley, 1800 feet high. />6. Granite of Palm Island. 



cc. Raised Plain, H miles long, 600 yards wide, and from 10 to 15 feet 

 above H.W.M. dd. Probable Contour of underlying Granite. 



On the southern side of this flat large quantities of pumice 

 occur, high above high water mark, and stretching inland for 

 some ten chains. The flat is covered at present with growths of 

 eucalypts, pandanus, and coarse grass about four feet in height. 



A similar though smaller occurrence was observed b}'^ Mr. 

 Hedley near Bentley's Creek. 



These flats, in my opinion, point undoubtedly to the redistri- 

 bution by tidal action of matter lost to the mainland and adjacent 

 islands, but principally by loss to the South Palm itself by the 

 forces of marine erosion acting on the windward side. 



