V.—What is Laterite?

Detrital Laterite or Lateritite.—Many of the so-called low-level laterites and some of the high-level laterites consist of admixtures of detritus from the various varieties of laterite already mentioned, with quartz and argillaceous detritus from granites and gneisses, the whole cemented together by the action of water on the lateritic constituents of the mixture. For such rocks the name detrital laterite is available, and could be used in all cases in which the reconstructed rock contained, say, at least 40 per cent of lateritic constituents. Theoretically, detrital laterites may contain, as an upper limit, 100 per cent of lateritic constituents, corresponding to the case of a detrital rock composed entirely of fragments of a pure laterite, without admixture of extraneous constituents. From the above it will be seen that I would allow greater elasticity in using the term laterite for the detrital forms than for those formed in situ (see next paragraph), provided the adjective detrital be carefully prefixed; for this word seems to me to imply the great variability of composition that must characterize these secondary laterites. But if it were considered desirable to avoid the use of the word laterite altogether in this connexion, the obvious term to use instead would seem to be lateritite, implying a rock the individual constituents of which are pieces of laterite. This term would be of great utility, and could be applied to all detrital and reconstructed lateritic rocks. The word is put forward here merely as a suggestion, but if geologists were to distinguish, in writing, between laterite, lateritoid, and lateritite, great clarity could be introduced into the literature of these substances.