Geological Society of London. 135 



metamorphosed beds of sandstone and limestone, without any alteration at the points 

 of contact, such as would be produced by an igneous rock. He also cited the crumpled 

 strata in the Maritime Alps, in which the granites were parallel with the other beds, 

 and seemed to form part of them. 



Mr. Carruthers mentioned that the late Prof. Fleming, twenty years ago, had 

 taught the same doctrine as to the nature of granite as that held by the lust speakers. 



Mr, David Forbes agreed that the crumpling of the strata was not due to the 

 intrusion of any eruptive rock. He completely disagreed with Prof. Eanisay and the 

 author as to the origin of granite, and maintained that, in the sedimentary rocks 

 traversed by the granite, the requisite ingredients for the formation of granite did not 

 exist. The proportion of felspar in quartzose rocks was iniinitesimally small, as com- 

 pared vrith that entering into the composition of granite. He could not accept the 

 notion of the heat from the interior approaching gradually to some portion of the 

 surface. 



Prof. Ramsay, in reply to Mr. Forbes, maintained that some of the slaty rocks of 

 "Wales, by extreme metamorphism, would pass into some kinds of granite. As to the 

 conditions of metamorphism of the rocks, this process must have gone on at a time 

 when these older rocks were overlain by a great thickness of more recent beds which 

 have since been removed by denudation. 



2, " On the connexion of Volcanic action with changes of Level." 

 By Joseph John Murphy, Esq., F.G.S. 



The author commenced by discussing the chemical theory of vol- 

 canic action, which he considered he had disproved. He remarked 

 on the coincidence of volcanic action with elevation of the surface, 

 but stated his opinion that the elevation of one part of the earth's 

 surface, and the depression of another, are the results of a movement 

 of subsidence in the following manner : — The interior of the earth 

 is constantly cooling, and as it cools it must contract. But the cold 

 strata of the surface cannot contract in the same proportion ; and as 

 they must remain in contact with the core, they are compelled to 

 form folds and ridges. The breaking out of volcanoes is due to the 

 breaking of part of the earth's crust by these foldings. According 

 to the author, " volcanic action is not the cause, but the effect of 

 secular changes of level ; and secular changes of level are due to the 

 subsidence of the suiface on the interior, as the interior contracts 

 in cooling." 



3. " On some Points in the Geology of the neighbourhood of 

 Malaga." By Don M. de Orueba. Communicated by Sir E. I. 

 Murchison, F.E.S., F.G.S. 



After referring to the wi-itings of previous authors upon the 

 geology of the south of Spain, the author noticed a mountain-chain 

 near Antequera, one branch of which, known as the " Torcal," he 

 described as presenting a very singular appearance, from the huge 

 blocks of stone of which it is composed. The division of the rock 

 into separate blocks, often of the most fantastic shapes, was attri- 

 buted by the author to denudation by water. The "Torcal" consists 

 of a compact limestone, generally of a red colour, resting conform- 

 ably on the east upon a fine-grained white oolitic marble of con- 

 siderable thickness. At the divisional line between the two forma- 

 tions many Ammonites were said to occur, and three of these were 

 doubtfully identified with A. gtganteus, hiplex, and annulatiis. These 

 species would indicate the deposit to be probably of Portland ian age. 



The plain of Antequera was considered by the author to consist 



