The nine or ten low islets, comprehended under the name of Palmerston’s Island, may be reckoned the heads or summits of the reef of coral rock that connects them together, covered only with a thin coat of sand, yet clothed, as already observed, with trees and plants, most of which are of the same sorts that are found on the low grounds of the high islands of this ocean.

There are different opinions amongst ingenious theorists concerning the formation of such low islands as Palmerston’s.  Some will have it, that in remote times these little separate heads or islets were joined, and formed one continued and more elevated tract of land, which the sea, in the revolution of ages, has washed away, leaving only the higher grounds; which, in time also, will, according to this theory, share the same fate.  Another conjecture is, that they have been thrown up by earthquakes, and are the effect of internal convulsions of the globe.  A third opinion, and which appears to me as the most probable one, maintains, that they are formed from shoals or coral banks, and, of consequence, increasing.  Without mentioning the several arguments made use of in support of each of these systems, I shall only describe such parts of Palmerston’s Island as fell under my own observation when I landed upon it.

The foundation is every where a coral rock; the soil is coral sand, with which the decayed vegetables have but in a few places intermixed, so as to form any thing like mould.  From this a very strong presumption may be drawn, that these little spots of land are not of very ancient date, nor the remains of larger islands now buried in the ocean; for, upon either of these suppositions, more mould must have been formed, or some part of the original soil would have remained.  Another circumstance confirmed this doctrine of the increase of these islets.  We found upon them, far beyond the present reach of the sea even in the most violent storms, elevated coral rocks, which, on examination, appeared to have been perforated in the same manner that the rocks are that now compose the outer edge of the reef.  This evidently shews that the sea had formerly reached so far; and some of these perforated rocks were almost in the centre of the land.

But the strongest proof of the increase, and from the cause we have assigned, was the gentle gradation observable in the plants round the skirts of the islands; from within a few inches of high-water mark to the edge of the wood.  In many places, the divisions of the plants of different growths were very distinguishable, especially on the lee or west side.  This I apprehend to have been the operation of extraordinary high tides, occasioned by violent, accidental gales from the westward, which have heaped up the sand beyond the reach of common tides.  The regular and gentle operation of these latter, again, throw up sand enough to form a barrier against the next extraordinary high tide or storm, so as to prevent its reaching as far as the former