﻿548 Geological Society, 



Banffshire : — At bottom a great thickness of arenaceous beds, more 

 or less altered into quartz-rock, gneiss, and mica-schist; next a 

 series of fine-grained clay- slates, in the midst of which is a bed of 

 limestone ; and then again an upper group of arenaceous strata. 

 The author stated that the arrangement of the rocks is very similar 

 to that occurring in Bute and Argyllshire. He remarked that the 

 general texture of the beds is fine-grained, and considered that they 

 were probably deposited in the depths of the sea, off the mouth of a 

 great river, the deposition of the argillaceous strata having taken 

 place during a period of increased depression. The deposition of the 

 beds was said to have probably taken place after the formation of 

 the (Cambrian) Bed Sandstone and Conglomerate of the North-west 

 Highlands, or in Lower Silurian times, the river by which the sedi- 

 ment was brought down being supposed to have drained the great 

 Laurentian region to the north-west. After their accumulation the 

 author supposed that " a glow of heat from beneath " approached 

 them, causing expansion and the wrinkling of the mass into folds 

 running from S.W. to N.E. The granites were considered by the 

 author to owe their origin to the fusion and recrystallization of the 

 arenaceous beds. 



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

 By Joseph John Murphy, Esq., E.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 surface on the interior, as the interior contracts 

 in cooling." 



3. " On some points in the Geology of the neighbourhood of Ma- 

 laga." By Don M. de Orueba. 



After referring to the writings of previous authors upon the geo- 

 logy of the south of Spain, the author noticed a mountain-chain near 

 Antequera, one branch of which, knownas the "Torcal," he de- 

 scribed 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" con- 

 sists of a compact limestone, generally of a red colour, resting con- 



