37 



AnJ, lastly, thoy refer the upper red sandstone and conglomerate to the new 

 red sandstone, which arrangement they believe to be confirmed by the formations 

 on the nearest main land of Scotland. 



They admit, however, that there arc some points of disagreement between these 

 strata and their supposed equivalents in many parts of Great Britain, and point 

 out in what particulars the dissimilarity consists; and, in connexion with this sub- 

 ject, remark: " If, therefore, the rocks of the Arran section were assumed as the 

 ' general type of all contemporaneous deposites, there would then bo no serious 



* objection to a classification attempted by some Continental and British geologists, 

 'wherein all the rocks of the orders above described are considered as belonging to 



♦ one great formation of red sandstone, of which the carboniferous series only forms 

 ' a subordinate part ; for, as we extend our generalizations, we must necessarily 



• diminish the number of our geological groups. We, therrfore, think that this 



* classification may have its advantage in comparing the contemporaneous depos- 



* ites of remote regions. It is certainly inapplicable to the English secondary 

 ' rocks, because the newer red sandstone is there always unconformable to the car- 

 ' boniferous, and, therefore, finds its true place in the superior order. This de- 

 ' monstrates that the carboniferous order of England was dislocated before the ex- 



• istence of the next superior order; but all dislocations are probably, in a certain 

 'sense, local phenomena; and, on that account, we do not think that a want of 

 ' conformiiy is one of the elements that will much assist us in grouping together, 

 'or in separating, contemporaneous deposites in distant parts of the earth." 



They believe even the oldsst of the granite to be newer than the new red sand- 

 stone, and that the trap in the southern part of the island is also newer; as it not 

 only traverses the sandstone in many places, but has overflowed it and formed 

 mountain masses of overlying rock. It must, therefore, have been in a much mon; 

 fluid state than the granite at the lime of the eruption. As it regards the age of 

 the trap, it is difficult to conjecture, and it is not improbable that there may have 

 been several periods of eruption, as the most of the Hebridean trap is newer than 

 the oolitic series, and in Ireland it is posterior even to the chalk. 



In reference to the granite mountains, they hazard the conjecture that the traps 

 had their origin below them; and if these eruptive forces were not able to break 

 through the thick covering of granite and primary schist, they may have acted on 

 thorn in the mass, have partially penetrated them, and been the very agents by 

 which they were elevated to their present altitudes. 



Monday, 2\st. — The first paper read this day in the Geological Section (Air. 

 Lyell in the chair) was " on the stratified deposites which constitute the Northern 

 and Central Regions of Russia,"' by Mr. Murchison, who, in company with M. 

 E. de Verneuil, Mcmbre.de Socicte Gcologique de Prance, had recently visited 

 Russia for the purpose of determining the relations of the older stratified deposites 

 tn that empire; and he took this early opportunity, in anticifiation of a more de- 

 tailed memoir, to lay the result (jf their investigation before the public. His lec- 

 ture being a mere sketch, my notes of it must necessarily be still more imperfect; 

 and I shall endeavor only to convey briefly some fuint idea of thi* truly interesting 



