Correspondence — J. Joly — Rev. Canon Bonney. 139 



magma) is far more indicative of formation by water, and is not usual 

 in pegmatites, so far as I know them ; if, indeed, all these are igneous 

 rocks. Mr. Lomas, however, may reply that he does not assert all 

 quartz veins, even if including felspar and mica, to be igneous, but 

 only that at Foxdale. But if so, we may fairly ask him to tell ns how 

 to distinguish igneous from aqueous veins. The former, when they 

 cut through sedimentary rock, especially if it be argillaceous, generally 

 produce rather conspicuous structural and mineral changes, so that 

 here I expected Mr. Lomas to give a careful description of the contact- 

 metamorphism or to offer an explanation of its absence. Instead of 

 this I find only the vague phrase ' altered slate ' — a phrase com- 

 patible with slight silicification or other changes such as may take 

 place by ordinary infiltration, and thus be no help to his hypothesis. 

 I do not deny that differentiation might possibly be carried so far in 

 an ordinary acid magma as to leave a residuum of pure or nearly pure 

 silica (though I have never met with an instance of it), but I think it 

 more probable that, as Mr. Lomas substitutes at critical points vague 

 phrases and inconsequent statements for precise description, he has 

 yielded to the fascination of a novel hypothesis. 



P.S. — The above was written before the publication of Mr. Harker's 

 letter (p. 95). T. G. Bonney. 



THE ORIGIN OF QUARTZ-VEINS. 

 Sir, — In connection with the question of the origin of certain 

 quartz-veins,' the fact that quartz reveals plastic qualities at 

 temperatures considerably below the melting-points of many 

 undoubted igneous minerals must be born in mind. J. Joly. 



Trinity College, Dublin. 

 February 9th, 1903. 



NEW GEOLOGICAL TERMS AND FALSE ETYMOLOGY. 

 Sir, — As no one seems inclined to protest against the terms 

 ' calcrete ' and ' silcrete ' with which Mr. Lamplugh proposes (in your 

 December number^) to disfigure geological nomenclature, I must 

 even raise a voice in the desert. Brief expressions for what he 

 intends them to convey would doubtless be useful, and no one would 

 be likely to quarrel with ' calcicrete ' and ' silicicrete,' of which one 

 would be two, the other three, letters longer. I admit that public 

 convenience may sometimes prevail over strict etymological rules, 

 as in preferring the inaccurate ' telegi'am ' to ' telegrapheme ' ; but 

 * calcrete ' and ' silcrete ' are even worse than the fashionable 

 mongrel ' peneplain,' and approximate in malformation to the hideous 

 ' phenocryst,' which seems invented to signalize the divorce of 

 geology from culture. T. G. Bonney. 



THE DEHYDRATION OF LATERITE. 

 Sir, — The very interesting paper on "The Constitution of 

 Laterite," by Mr. T. H. Holland, appearing in your issue for 

 February, 1903, raises several questions of chemical physics which 



1 See Mr. J. Lomas's article. Geological Magazine, January Number, p. 34, 

 and Mr. Alfred Harker"s letter, February Number, p. 95. 

 - Geol. Mag., December, 1902, p. 575. 



