1876.] GEOLOGY. 215 



sited such coarse gravel over the almost level platforms 

 between the valleys. My view differs from that of Hoist, 

 p. 415 ['Great Ice Age'], of which I had never heard, as his 

 relates to channels cut through glaciers, and mine to beds 

 of drift interstratified with frozen snow where no glaciers 

 existed. The upshot of this long letter is to ask you to 

 keep my notion in your head, and look out for upright 

 pebbles in any lowland country which you may examine, 

 where glaciers have not existed. Or if you think the notion 

 deserves any further thought, but not otherwise, to tell any 

 one of it, for instance Mr. Skertchly, who is examining such 

 districts. Pray forgive me for writing so long a letter, and 

 again thanking you for the great pleasure derived from your 



book, 



I remain yours very faithfully, 



CH. DARWIN. 



P.S. . . . I am glad that you have read Blytt ;* his paper 

 seemed to me a most important contribution to Botanical 

 Geography. How curious that the same conclusions should 

 have been arrived at by Mr. Skertchly, who seems to be a 

 first-rate observer ; and this implies, as I always think, a 

 sound theoriser. 



I have told my publisher to send you in two or three days 

 a copy (second edition) of my geological work during the 

 voyage of the Beagle. The sole point which would perhaps 

 interest you is about the steppe-like plains of Patagonia. 



For many years past I have had fearful misgivings that it 

 must have been the level of the sea, and not that of the land 

 which has changed. 



I read a few months ago your [brother's] very interesting 

 life of Murchison.f Though I have always thought that he 

 ranked next to W. Smith in the classification of formations, 



* Axel Blytt. ' Essay on the I m- sons.' Christiania, 1876. 

 migration of the Norwegian Flora \ By Mr. Archibald Geikie. 

 during alternate rainy and dry Sea- 



