304 Analyses of Books. [Oct. 



are deposited from a liquid in the state of crystals, they do not 

 assume the form which we find in the clay or the sand which is 

 accumulated at the bottom of ponds, and to which the name of 

 strata or beds has been given. In these we find a layer, for 

 example, of clay, of a certain definite thickness, the top and 

 bottom of which consist of planes nearly parallel, covering the 

 bottom of the pond. This is followed by a layer of sand, of 

 similar dimensions. Then comes a layer of clay, and then 

 another of sand, and these alternations continue to be repeated 

 for a greater or smaller number of times according to circum- 

 stances. 



Now all rocks are either stratified or not stratified, and a 

 great diversity of opinion exists among geologists whether 

 certain rocks are to be considered as stratified or not. The 

 origin of this difference and of the disputes on the subject, 

 which still continue so numerous, is no doubt the different con- 

 clusions deduced by geologists respecting the origin of certain 

 rocks. Hutton and Playfair, who were of opinion that granite 

 and greenstone had been fused by fire, and elevated in a melted 

 state into the situations in which we now find them, could not 

 admit the stratification of these rocks, because such an admis- 

 sion would have been inconsistent with their opinions respecting 

 the first principles of geology. It would seem at first sight that 

 Werner and his pupils, who considered granite as deposited in 

 crystals from a liquid, ought likewise to have denied the 

 existence of that rock in regular strata. This they probably 

 would have done had they been sufficiently conversant with the 

 phenomena of chemistry ; but their ignorance of that science, 

 and the contempt in which they were accustomed to hold it, 

 together with their eagerness to refute the favourite doctrines of 

 their antagonists, led them to adopt too inconsiderately the 

 notion that granite is often stratified. But as the term stratifi- 

 cation cannot be applied to the crystallized rocks in the same 

 sense that it is applied to those that consist of mere mechanical 

 mixtures cemented together, as sandstone and clay, we find the 

 most contradictory statements respecting the stratification of the 

 very same granite rocks. Granite is stratified in the Reisenge- 

 birge, says Gruber, Charpentier, Schubert, Deluc, Dr. Mitchell, 

 and Prof. Jameson ; but Von Buch denies the stratification alto- 

 gether. Schubert considers the Erzegebirge granite as strati- 

 fied, Von Buch as unstratified. Deluc describes the granite of 

 the Fichtelgebirge as stratified ; but our author, who examined 

 it with Messrs. Buckland and Conybeare, could perceive no 

 traces of stratification. We find the same diversity of opinion 

 with respect to the granite in the Alps and the Pyrenees. 

 Indeed if we compare the stratification of Mont Blanc, which, 

 according to Saussure, consists of only three or four vertical 

 beds, with that of the coal strata in any part of Great Britain, it 

 must be obvious that the term must have a different meaning in 



