18401881] EARTH-MOVEMENTS 125 



wish to read them over again ; I have, however, re-lent your Letter 483 

 work to Mrs. Rich, who, like all whom I have met, has been 

 much interested by it. I will stop about my own Geology. 

 But I see I must mention that Scrope did suggest (and I 

 have alluded to him, p. iiS, 1 but without distinct reference 

 and I fear not sufficiently, though I utterly forgot what he 

 wrote) the separation of basalt and trachyte ; but he does not 

 appear to have thought about the crystals, which I believe 

 to be the keystone of the phenomenon. I cannot but think 

 this separation of the molten elements has played a great 

 part in the metamorphic rocks : how else could the basaltic 

 dykes have come in the great granitic districts such as 

 those of Brazil ? What a wonderful book for labour is 

 d'Archiac ! . . . 2 



To Lady Lyell. Letter 484 



Down, Wednesday night [1849 ?]. 



I am going to beg a very very great favour of you : it 

 is to translate one page (and the title) of either Danish or 

 Swedish or some such language. I know not to whom else 

 to apply, and I am quite dreadfully interested about the 

 barnacles therein described. Does Lyell know Loven, 3 or 

 his address and title ? for I must write to him. If Lyell 

 knows him I would use his name as introduction ; Love"n I 

 know by name as a first-rate naturalist. 



Accidentally I forgot to give you the Footsteps, which I 

 now return, having ordered a copy for myself. 



I sincerely hope the " Craters of Denudation " 4 prosper ; I 

 pin my faith to this view. 



1 Geological Observations, Ed. II., 1876. Chapter VI. opens with a 

 discussion " On the Separation of the Constituent Minerals of Lava, 

 according to their Specific Gravities." Mr. Darwin calls attention to the 

 fact that Mr. P. Scrope had speculated on the subject of the separation 

 of the trachytic and basaltic series of lavas (p. 113). 



2 Possibly this refers to d'Archiac's Histoire des Progres de la 

 Geologic, 1848. 



3 S. L. Loven published numerous papers on Cirripedes and other 

 zoological subjects in the Stockholm Ofuersigt and elsewhere between 

 1838 and 1882. 



4 " On Craters of Denudation, with Observations on the Structure 

 and Growth of Volcanic Cones." Proc. Geol. Soc., Vol. VI., 1850, 

 pp. 207-34. In a letter to Bunbury (Jan. i7th, 1850) Lyell wrote : 



