458 Dr. L. Leigh Fermor — What is Laterite ? 



he finds free aluminium hydroxide in weathered granite, in kaolin, 

 and in slate, as well as in all the Malayan laterites. 



Dr. Evans 1 then allows the permissibility of using the term lauxite 

 as a commercial mineral term to apply to laterites exceptionally poor 

 in silica and in iron, provided it is understood that it is not to be 

 employed as a rock name. 



Air. Scrivenor 2 replies to Mr. Crook in the same part of this issue, 

 and quotes Lacroix as saying Avith regard to lauxite, " C'est en realite 

 une veritable roche." At the same time Mr. Scrivenor quotes an 

 experiment in which he obtained over 13 per cent of alumina from 

 decomposed granite, which should therefore, according to the definition 

 advocated by Crook and Evans, be designated laterite, although no one 

 in the Malay States regards it as such. 



The correspondence in the pages *of this Magazine ends here, 

 for the time at least; but Professor Harrison, apparently tinder the 

 stimulus of the original Imperial Institute review and of the sub- 

 sequent discussion, from which he has quietly held aloof, has 

 meanwhile had carried ont a series of chemical analyses of the 

 residual earths of British Guiana, whicli he describes in conjunction 

 with Mr. K. D. Beid, in a paper extending into three numbers of 

 this Magazine. 3 This paper is one of considerable importance, as 

 it furnishes valuable material for the discussion of the composition 

 of tropical surface decomposition products. Incidentally I may 

 remark that it seems in my opinion to justify in full the objection 

 advanced in the Imperial Institute review to Professor Harrison's 

 use of the word laterite, for not more than a very few of the rocks 

 and soils analysed are worthy of this name, such terms as lateritic 

 soil and clay being more suitable. 



III. Thr Nomenclature of Late kite. 



In the sequel I propose to discuss Professor Harrison's paper at 

 greater length, but it is first necessary for me to advance my own 

 views on the subject. During recent years I have had field experience 

 in various parts of the peninsula of many occurrences and varieties 

 of Indian laterite. I have examined rocks that I regard as true 

 laterites in the Balaghat and Jabalpur districts of the Central 

 Provinces, in the Belgaum and Satara districts of the Bombay 

 Presidency, in the Portuguese territory of Goa, and in the Saudur 

 Hills in Madras; whilst of the type of lateritic rock I call lateritoid 

 I have seen occurrences in the Siughbum district of Bengal, in 

 Jabalpur, in Goa, in the Sandur Hills, and in the districts of 

 Chitaldrug, Kadur, Shimoga, and Tumkur in Mysore; and, finally, 

 1 have examined the lithomargic decomposition products with a little 

 laterite of the Mlgiri Hills. The consideration of these occurrences 

 and of the specimens obtained therefrom, and also the work, published 

 and unpublished, of such of iuy colleagues as have had extensive 

 experience of laterite, particularly that of Sir Thomas Holland and 

 Messrs. Hayden and Middlemiss, have led to very definite ideas as 



1 Geol. Mag., 1910, p. 382. 2 Op. cit., p. 384. 



3 1910, pp. 439-52, 488-95, 553-62. 



