The Formation of Coral Reefs

Abstract

IN NATURE for February 18 there is a paper by Mr. J. S. Gardiner giving a concise account of his theory of coral reefs. A more extended paper by him on the same subject appeared in the Geographical Journal for 1902, and was followed last year by one by Mr. Gunther on erosion on the west coast of Italy; the latter author proves, on a coast with a very strong sand scour and with loose calcareous rocks on the fore-shore, that below “wind and water” mark no erosion to any appreciable extent goes on. Mr. Gunther's observations coincide with those of every day experience, and should no one have already protested against Mr. Gardiner's views, will you let me record my most vigorous dissent? The principles of geology are so little understood, and it requires such a level head in sorting out the true from the false from among the apparently conflicting evidences that one has to deal with, that I think when such a glaring misconception of the processes of nature as that of Mr. Gardiner's is repeated in scientific journals some stand should be made before more mischief is done. It is a disadvantage on my part not to have worked on coral reefs myself, but I have been working for ten years on a coast which is fringed with coral reefs only a short way from where I have seen it, and I have therefore been able to study the base of the reefs without the disguising covering of coral limestone. I have seen beaches crowded with the shells of animals still living in the adjoining sea, raised two and three hundred feet above sea-level, and a short distance away I have seen consolidated sand-dunes going far below sea-level; while from the submerged plateau the edge of which is called the Agulhas Bank, Dr. Gilchrist has dredged large water-worn boulders far out to sea. South Africa generally is a rising area, but in a sinking area the exact converse is true, namely, that with a general sinking local elevations must occur. This last is not a new statement of fact, but a well established experience, and one that has been treated of again and again, for instance, by Suess, in his “Antlitz der Erde,” vol. ii. chapter i., and is one which I believe can be proved on any coast—it is well brought out in Mr. Gunther's paper, and in many descriptions of coral islands; with such a statement before one, I am at a loss to understand where the room comes in for Mr. Gardiner's theory, or where are the difficulties which led to the manufacture of the hypotheses of Messrs. Murray and Agassiz. The one fundamental idea that dominates the whole conception of the earth's structure is that the crust is never at rest, but is incessantly rising and falling; and a corollary is that each great rise or fall is never continuous, but is the result of the surplus of a series of + and movements. If we are to adopt Mr. Gardiner's view that submarine erosion can cut down solid rock to 200 fathoms below the surface of the water, geology must be deposed from its pedestal as a science, and relegated to the class which includes gnostic theology and such like.