194 Transactions. — Geology. 



heaval I am now referring to. According to Captain Beechey 

 the island is five miles long and one mile wide, and has a flat 

 surface, nearly 80 ft. above the sea. All sides, excepting the 

 north, is bounded by perpendicular cliffs, about 50 ft. high, 

 composed entirely of dead coral, which are considerably 

 undermined by the action of the waves. (This is exactly 

 what one sees at Vavau, Tonga, and I recommend visitors not 

 to miss pulling into one of these caves at the entrance to 

 Vavau Harbour). Byron's Cave there, I expect, was similarly 

 formed. 



The external form of the Gambler Islands, in the Paumo- 

 tus, conveys at once an impression of their volcanic origin, 

 but the seventy-eight islands or groups of islands comprising 

 the Paumotus are generally low islands almost a-wash. The 

 hurricane of 1878, indeed, swept over some of them, carrying 

 every living thing away. It is not often this group is visited 

 by such cyclones. Many of the inhabitants saved themselves 

 by tying themselves to the trunks of trees. It may be that 

 the whole of the Paumotu Islands, under the 200 ft. level, 

 appeared above the sea at the same upward movement to 

 which I am at present referring. The uprising tapered off, as 

 it were, at a little beyond Easter Island, and affected the 

 whole equatorial area right through, perhaps to the western 

 coast-line of the Austrahan Continent. It will be noticed 

 that the 20th parallel of south latitude very nearly cuts all 

 these islands. 



The distance from the Loyalties to Henderson Island is 

 about 3,580 miles, and the evidence which I have been able to 

 produce shows one area of upheaval. It will be noticed, too, 

 that this line is almost at right angles to the first line of pre- 

 sent volcanic activity referred to in this paper, bounding the 

 180th parallel of longitude from Tarawera to Nei-afo, a dis- 

 tance of fifteen hundred miles, or in its fullest extent from 

 Mounts Erebus and Terror to the equator, a distance of 

 about four thousand five hundred miles; the second line of 

 activity, from Hunter Island and through the New Hebrides, 

 the Solomons, and New Britain, &c., to the longitude of 

 Vulcan Island in New Guinea or Uap in the Carolines, being 

 fully 2^250 miles ; but this latter line would be better extended 

 another two thousand miles of eastern longitude, so as to 

 include the whole line of present activity through the Malay 

 Archipelago. 



Keference will be made directly to the islands immediately 

 bordering on and north of the equator, which are all, with few 

 exceptions, low and small. All these show subsidence. There 

 are a great number of crescent- and low-shaped atolls in these 

 northern, central, and eastern portions of the Pacific ; also 

 small, circular, sunken patches of coral, showing that during the 



