Corresjwndence — 3Ir. J. B. Scrivenor. 431 



been worked on Mindanao, and some gold has been obtained in a region 

 of schistose rocks. The Sulu group consists mainly of volcanic rocks 

 and coral formations. 



11. Museum of Practical Geology, Jermyk Street, S.W. — 

 A Short Guide to the Museum (pp. 48, and price Id.) has just been 

 issued. It contains useful plans of the several floors of the Museum, 

 and descriptions of the principal objects exhibited, including minerals, 

 rocks, fossils, geological maps, and models. Many changes and 

 improvements have been made in the display and arrangement of 

 specimens since 1896, when the last handbook to the Museum was 

 published. Space might have been found in this new Guide for 

 a Table of Contents. 



COE,RESI=OITXDE]SrOE. 



THE USE OF THE WORD 'LATERITE'. 



Sir, — I have just seen in the last number of the Imperial Institute 

 Bulletin (1909, vol. vii, No. i) a review of Professor J. B. Harrison's 

 Geology of the Goldfields of British Guiana, in which the reviewer 

 takes exception to Professor Harrison's use of the word ' laterite ' as 

 being "wider than is either usual or desirable" (p. 134 of the 

 Bulletin), and the reviewer states that only products of weathering 

 containing free aluminium hydroxide in hot, moist climates should be 

 considered as laterite. 



In the light of the recent literature on the subject, the proposition 

 that it is desirable to restrict the term ' laterite ' to that pi'oduct of 

 weathering in hot, moist climates which contains free aluminium 

 hydroxide carries great weight ; indeed, I had almost said that 

 it is the counsel of perfection, one attribute of which it certainly 

 possesses, namely, that it is impracticable. The reason of this is that 

 the term ' laterite ' has been used, in the Malay Peninsula at least, 

 for many years by a large body of engineers for what are essentially 

 masses of iron oxide replacing portions of weathered rock and filling 

 fissures in such rocks near the surface. This (Malayan) laterite is 

 most abundant in weathered schists, and is largely used for public 

 works. Small quantities of aluminium hydroxide may or may not 

 be present in these masses of ironstone, but that question is of no 

 immediate importance to the engineer, who values the stone for its 

 hardness. 



I have talked this matter over with one of the senior ofiicers of 

 the Public Works Department and he agrees with me that ' laterite ' 

 is an engineer's rather than a geologist's term, covering rocks of 

 varying composition ; and I am strongly inclined to think that we 

 should do well to call rock that we say are bauxites by their accepted 

 mineral name, instead of attempting to lay down what shall and what 

 shall not be called ' laterite '. 



It is clear that the reviewer of Professor Harrison's book does 

 not appreciate the- difficulties awaiting those who attempt to instruct 

 engineers in the use of the term 'laterite '. It is a task that would, 



