Sl8 SCittltl^IC NElVS. 



scribed several species of transition-porphyry a^ occlifrib* 



along with gray-wacke, &c., in different parts of Scotland* 



Floetz-por- He also gave a particular account of a floetz- porphyry, which 



phyry. likewise occurs in Scotlondj and appears to belong to the 



old red sandstone formation* The professor conjecturedj 



that this floetz-porpbyry may be the mother-stone of ihe 



Lavas in rocks porphyritlc felspar laVas, which are found In some coun* 



than^ the new- ** ^^* • ^"'^ consequently that lavas may occur in rocks of 



cit floetz-trap. "n older date, than those of the newest floetz-trap series* 



Shark genus. At the same meeting Mr. W.E. Leach read a description of 



two species of shark found in the 3cottish seas, illustrative 



of a proposed subdivision of the genus squalus of Linneeus* 



Geologyofthe At the meeting on the 1st of February a communication 



Campsie hills. f,.ojjj Ljeut. Col. Imrie was read, containing an account of 



the district of country in Sterlingshire called the Campsie 



Hills, illustrated by some interesting geological facts ob* 



served by the Colonel on the coast of the Mediterranean* 



The Campsie Hills consist of trap rocks of great thickness ; 



under which sandstone occurs; and below this lie beds of 



limestone, with slate-clay, clay iron-stone, and some seams 



Columnar of coal. The trap is in some places distinctly columnar ; 



*'^*P' and in many other places, it shows a tendency to this form. 



He observed, that these circumstances might give occasion 



to some geologists to class the trap of the Campsie district 



This structure with volcanic products, of which however he saw no sym* 



frthl^'moU?^ P*<^™- ^'^ *^^" pointed out, that nature produces these 



and dry way. forms both in the moist and in the dry way» and gave exam- 



The moist pies of both, In the moist way, he said, that these forms 



are seen in greatest perfection in warm climates ; and drew his 



exemplified example, in this mode, from the coast of Africa, near the 



site of ancient Carthage; where a small lake with a deep 



clay bottom had been accidentally drained by the breaking 



down of a part of its barrier, and where the clay deposit had 



split into vertical columns eighteen feet high, and from a foot 



the dry and a half to three feet in diameter. The example m the 



jfrom Felacu- dry way he took from the island of Felacuduf one of the 



most westerly of the Lipari islands. In the lavas of that 



island, which have taken the columnar form, he mentioned 



having seen obsidian and pumice, which had been in flow 



with the lava, and are seen combined in one of its congealed 



btTeaoKS* Geological 



