26 THE GEOLOGY OF BEEMUDA. 



substances, chiefly peroxide of iron and alumina, silica, and some earthy 

 I)hosphates. Now these substances are to a very small degree soluble 

 in water charged with carbonic acid ; consequently, after the gradual 

 removal of the lime, a certain sediment, a certain ash, as it were, is left 

 behind. One per cent, seems a very small proportion, but we must 

 remember that it represents one ton in every hundred tons of material 

 removed by the action of water and of the atmosijhere ; and the evi- 

 dences of denudation on a large scale are everywhere so marked, that,, 

 even were some portion of this 1 per cent, residue further altered and 

 washed away, enough might still be left to account fully for the whole 

 of the red earth."* Assuming the " red earth" to be the insoluble resi- 

 due left bj'^ the solution of the major part of the calcium carbonate of 

 the coral rocks, it should be observed that its materials doubtless have 

 the same twofold origin which has been recognized in the case of the 

 somewhat analogous red clays of the deeper parts of the ocean bottom, t 

 They are doubtless in part derived from the minute quantity of non- 

 calcareous mineral matter existing in the corals, shells, and other cal- 

 careous skeletons of marine animals and plants ; in part from the 

 decomposition of volcanic minerals, which are continually being trans- 

 ported in various ways to all oceanic islands. Analyses of samples of 

 the "red earth" are quoted by Thomson | from a "Report from Professor 

 Abel, F. R. S., to H. E. General Lefroy, 0. B., F. R. S., on the Character 

 and Composition of Samples of Soil from Bermudas." 



PHENOMENA RESULTING FROM UNEQUAL HARDENING OF THE LIME- 

 STONE. 



A number of interesting phenomena result from the unequal hardening 

 of the sand-rock where vegetable stems or roots or other accidents have 

 determined the location of channels for the percolating waters. On the 

 weathered surface of clifls and banks of the drift-rock may often be ob- 

 served hard bodies somewhat projecting, consisting of a more firmly con- 

 solidated sand-rock, having the form of slender cylinders irregularly 

 branching, the main trunks being generally nearly vertical. These stems, 

 may generally be seen to be tubular, and in the slender cavity may gener- 

 ally be found more or less of woody fiber. These bodies have much the 

 form and aspect of the " branched bodies" observed by Darwin at King 

 George's Sound on the south-west coast of Australia, and at the Cape of 



'Thomson, op. dt., Vol. I., pp. 294, 295. 



t Thomson, op. cit., Vol. I., pp. 215-218; Vol. II., pp. 255, 256. 



t Op. cit, Vol. I., pp. 325, 326. 



