In an article with the above heading (GEOL. MAG., Vol. LXIV, 1927, p. 518) Mr. L. J. Chubb discussed the geology of these two small Pacific islands, which are somewhat centrally situated in the western part of the South Pacific Ocean.

Dr. F. W. Clarke truly observes in regard to the origin of chert: “No one process can account for all the occurrences of amorphous and cryptocrystalline silica, and each locality must be studied in the light of its own evidence.” (Data of Geochemistry, 1916, p. 544.)

We have perhaps gone a little further into the detail of these five zones than is justified by the nature of this paper. But as we shall see later, unless the supreme importance of these east and west zones be fully appreciated, we should be at a loss to explain the peculiar arrangement of the several mountain ranges that swell forward towards the continental margin, as well as the succession of island arcs that border the continental mass of Eastern Asia.