Geological Society. S91 



at present at the royal powder-mills at Waltham Abbey. 

 The stone itself is a dark blue slaty litnestone, containing 

 comminuted fragments of marine remains ; the vein by 

 which it is traversed is whitish compact carbonate of lime. 

 This vein, in its present state, consists of a number of 

 separate angular fragments, having somewhat of a general 

 parallelism, vvith such a correspondence at any two neigh- 

 bouring extremities, as to render it a matter past doubt 

 that thfey have once formed a continuous vein. To dis- 

 place such a vein into its present position, it is necessary 

 to suppose that the'r(ick. originally consisted of a series of 

 very thin strata, which being fissured across, formed a 

 space for the reception of the sunstance of the vein. It is 

 evident from the angularity, and the irregularly serrated 

 edges of the displaced fragments, that the white calcareous 

 carbonate must have been perfectly indurated at the time 

 of its displacement ; yet, that the strata of the liniestone 

 must have been in a state to admit of a series of shifts or 

 slides, each successively advancing with equal intervals 

 beyond the one preceding it : it is necessary also to sup- 

 pose that the strata must have been in some condition 

 admitting them to adhere intimately together, either at 

 the period when the slides took place, or afterwards, from 

 the perfect obliteration of the seam. By what theory can 

 these facts be explained ? 



Friday, Nov. 20, — The President in the Chair. 



Mr. Dunston, having signed the obligation, was admitted 

 a member of the Society, 



The Right Hon. Dundas was elected an ordinary 



member of the Society. 



Thomas Murdoch, F. R.S. of New Cavendish street, 

 Portland Place ; 



George TuthiU, M. D. F. R. S. of Soho Square ; 



Mr. William Nicholson, civil engineer, Bloomsbury 

 Square ; 



Thomas EJare, Esq. surgeon, Argyle-street ; 

 were severally pro|)osed as ordinary members of the Society. 



The Secretary reported that the foUowintr conununicatiou 

 had been received, viz. " Observations on abed of green- 

 stone near Walsall in Staffordshire," by Arthur Aikin, Esq. 

 Secretary. 



The Secretary further reported, that the following present* 

 had been received ; and thanks were voted for the same, viz. 



1. Specimens of rocks from Sicily from Dr. Franck, 

 M.G.S. 



2. Specimens illustrative of Mr. Aikin's paper. 



B b 4 %. Two 



