1846—1856] CLEAVAG'E \NI> FOLIATION 201 



of section. I read Studer's paper carefully, and drew the Letta 

 conclusion stated from it ; but I may very likely be in an 

 error. I only state that I have frequently seen cleavage- 

 laminae dipping inwards on mountain sides; that I cannot 

 give up, but I daresay a general extension of the rule (as 

 might justly be inferred from the manner of my statement) 

 would be quite erroneous. Von Buch's statement is in his 

 Travels in Norway ' ; I have unfortunately lost the referen< 

 and it is a high crime, I confess, even to refer to an opinion 

 without a precise reference. If you never read these travels 

 they might be worth skimming, chiefly as an amusement ; 

 and if you like and will send me a line by the general post of 

 Monday or Tuesday, I will cither send it up with Hopkins 

 on Wednesday, or bring it myself to the Geological Society. 

 I am very glad you are going to read Hopkins-; his vie. 

 appear to me eminently worth well comprehending ; false 

 views and language appear to me to be almost universally 

 held by geologists on the formation of fissures, dikes, and 

 mountain chains. If you would have the patience, I should 

 be glad if you would read in my / 'oleanic Islands from p. 65, 

 or even pp. 54 to 72 — viz., on the lamination of volcanic 

 rocks ; I may add that I sent the scries of specimens there 

 described to Professor Forbes of Edinburgh, and he thought 

 they bore out my views. 



There is a short extract from Prof. Rogers 3 in the last 

 Edinburgh New Phil. Journal, well worth your attention, on 

 the cleavage of the Appalachian chain, and which seems 

 far more uniform in the direction of dip than in any case 

 which I have met with ; the Rogers doctrine of the ridge 

 being thrown up by great waves I believe is monstrous ; 

 but the manner in which the ridges have been thrown over 

 (as if by a lateral force acting on one side on a higher level 

 than on the other) is very curious, and he now states that the 

 cleavage is parallel to the axis-planes of these thrown-over 

 ridges. Your case of the limestone beds to my mind is the 



1 Travels through \ way and Lapland durin wars iSot> 



London, 1S13. 



' J " Researches in Physical Geology." By W. Hopkins. Phil. Trans. 

 A'. Soc, 1839, p. 3S1 ; ibid, 184 2, p. 43, etc. 



3 "On Cleavage of Slate-strata." Edinburgh New Phil. Journ., 

 Vol. XL I., p. 4:-:, 1846. 



