394 



Brescina in the Alps, and the Altai chain ; — all of which occur in 

 districts where unstratified rocks are known to exist. 



The author, however, states that besides the evidence thus afforded 

 of the connexion of igneous rocks with metalliferous deposits, it is 

 necessary to have a knowledge of the stratification of the formations 

 in which mines are worked before any legitimate conclusion can be 

 drawn. 



In reply to the third question, — Do there exist metalliferous depo- 

 sits entirely disconnected from unstratified rocks ? — The author enu- 

 merates the mines of the Netherlands ; those of quicksilver at Idria ; 

 the lead mines of Poggau in the valley of the Mur ; Pezay and Ma- 

 coz in the Tarentaise ; and the veins of galena in the mountain- 

 limestone of the south-west of England. 



The author then gives, as a general illustration of his subject, a 

 sketch of the countries between the Alps and the western extremity 

 of England, and shows that igneous rocks and metallic deposits are 

 totally wanting in the whole of the districts extending from the foot 

 of the Alps across the valley of Lac Leman, the Jura chain, the plains 

 of Franche Comte and Burgundy; and in the oolitic, green-sand, 

 chalk and tertiary formations of the north-west of France, and in the 

 tertiary and secondary formations of England as far as Devonshire ; 

 but that, on the contrary, as soon as the unstratified rocks recom- 

 mence in the last-mentioned district, metallic veins reappear. 



Lastly, the author compares the relative connexion of igneous de- 

 posits with metallic accumulations, and states that ores are more 

 abundant in granite, certain porphyries, syenites, amygdaloids, and 

 trap, which he calls underlying, unstratified rocks, than in the newer 

 porphyries, the dolorites, and the true volcanic formations, which he 

 distinguishes by the term of overlying, unstratified rocks ; and he al- 

 ludes to the assistance which the practical r/iiner would derive from 

 attending to this distinction, and to the principal object of the paper, 

 ■ — the connexion of igneous with metalliferous deposits. 



April 1 1th. — Peter Frederick Robinson, E^q., Lower Brook-street, 

 was elected a Fellow of this Society ; and the name of John Buddie, 

 Esq. was removed, by ballot, from the honorary to the ordinary list of 

 Fellows. 



A Letter from George Gordon, Esq., addressed to Roderick Im- 

 pey Murchison, Esq. P.G.S., noticing the existence of lias on the 

 southern side of the Murray Firth, was first read. 



Mr. Gordon, after referring to the memoir of Professor Sedgwick 

 and Mr. Murchison on the North of Scotland, in which lias is shown 

 to occur on the northern side of the Murray Firth, points out the 

 existence at Linksfield or Cutley-hill near Elgin, of a stratum of clay 

 inclosing thin bands of limestone, and occupying a position analo- 

 gous to that of the lias on the northern side of the Firth. Mr. Gor- 

 don likewise states, that in making the canal to drain Loch Spyine, 

 a bed of clay was penetrated containing numerous specimens of Be- 

 lemnites ; and he conceives that a great part of the bay of Lossie- 

 mouth belongs to that formation. 



A paper was then read " On the strata in the immediate neigh- 



