200 GEOLOGY [Chap. IX 



Letter 536 paper 1 recognised. I had always thought that Studer 2 was 

 one of the few geologists who had taken a correct and enlarged 

 view on the subject. 



Letter 537 To D. Sharpe. 



Down [Nov. 1846]. 



I have been much interested with your letter, and am 

 delighted that you have thought my few remarks worth 

 attention. My observations on foliation are more deserving 

 confidence than those on cleavage ; for during my first year 

 in clay-slate countries, I was quite unaware of there being 

 any marked difference between cleavage and stratification ; 

 I well remember my astonishment at coming to the con- 

 clusion that they were totally different actions, and my 

 delight at subsequently reading Sedgwick's views 3 ; hence at 

 that time I was only just getting out of a mist with respect 

 to cleavage-laminae dipping inwards on mountain flanks. I 

 have certainly often observed it — so often that I thought 

 myself justified in propounding it as usual. I might perhaps 

 have been in some degree prejudiced by Von Buch's remarks, 

 for which in those days I had a somewhat greater deference 

 than I now have. The Mount at M. Video (p. 146 of my 

 book) 4 is certainly an instance of the cleavage-laminae of a 

 hornblendic schist dipping inwards on both sides, for I 

 examined this hill carefully with compass in hand and note- 

 book. I entirely admit, however, that a conclusion drawn 

 from striking a rough balance in one's mind is worth nothing 

 compared with the evidence drawn from one continuous line 



1 Probably the paper " On Slaty Cleavage." Quart. Journ. Geol. 

 Soc., Vol. III., p. 74, 1847. 



2 Several of Bernhard Studer's papers were translated and published 

 in the Edinburgh New Phil. Journ. See Vol. XL 1 1., 1847 ; Vol. XL IV., 

 1848, etc. 



3 " Remarks on the Structure of Large Mineral Masses, and especially 

 on the Chemical Changes produced in the Aggregation of Stratified Rocks 

 during different periods after their Deposition." Trans. Geol. Soc, 

 Vol. III., p. 461, 1835. In the section of this paper dealing with cleavage 

 (p. 469) Prof. Sedgwick lays stress on the fact that "the cleavage is in 

 no instance parallel to the true beds." 



4 Geol. Obs. S. America, p. 146. The mount is described as con- 

 sisting of hornblendic slate ; " the lamina? of the slate on the north and 

 south side near the summit dip inwards." 



