430 Hcports and Proceedings — Geologists' Association. 



Bobert Sim, M.D. — Oa Certain Quartz Nodules occurring in the 



Crystalline Schists near Killin, Perthshire. 

 W. Molyneux, F.G.S. — On the Occurrence of Copper and Lead Ores 



in the Bunter Conglomerates of Cannock Chase. 

 T. Ogier Ward, M.D. — On the Formation and Stratification of Sedi- 

 mentary Eocks. 

 T. Ogier Ward, M.D. — On Slickensides, or Eubbed, Polished, or 



Striated Eocks. 

 T. McK. Hughes — On the Announcement by Mr. J. W. Judd of 



Cretaceous Eocks in the Western Islands of Scotland. 

 Prof. Tennant — To Exhibit Specimens of Diamonds from the Cape 



of Good Hope. 

 E. B. Beadwin — On the Arigna Coal and Iron District of the West of 



Ireland. 



Geologists' Association. — July 5, 1872. — J. U. Ilott, Esq., 

 in the Chair. — 1. " Corbicula fluminalis, its Associates and Distribu- 

 tion," by Alfred Bell. 



Having traced the distribution, both in place and time, of Corhicula 

 fluminalis, the author pointed out its value in discriminating various 

 geological horizons, especially in the valley of the Thames, and 

 commented on the peculiar distribution of the different species of 

 Unio associated with it, Unio littoralis only occurring in the gravels 

 and brick-earth of Kent, at Crayford, and Erith, and Unio tumidus 

 and Unio pictorum being equally confined to those of Essex and 

 Middlesex, at Grays, Ilford, and Hackney Downs. 



The difference in the size of the Corbicula from these localities 

 was also noticed, and the inference suggested from these peculiarities 

 was, that the Essex gravels and brick- earth were newer than those 

 of Kent. All these were, however, anterior to those gravels in the 

 Thames Yalley which have yielded palaeolithic flint implements, 

 none of which have produced either the Corbicula or Unio littoralis. 

 A cast of a flint flake found at Crayford by the Eev. Osmond Fisher 

 below the Corbicula-beds was shown by the author, who did not 

 concur in its being indicative of the presence of man at that early 

 date, since, he considered, natural ^encies were equally capable 

 of producing such flakes.^ 



2. " On the Dip of the Chalk in Norfolk, and the Eemains of Old 

 Land-surfaces called the ' Stone-bed,' " by John Gunn, M.A., F.G.S. 



Mr. Gunn showed that the dip of the Chalk from Hunstanton to 

 Yarmouth averaged twenty-nine feet per mile. This he arrived at 

 by computing the extent of the surface of the Chalk from Norwich 

 to Yarmouth, where the Chalk was reached by the boring of an 

 artesian well, and the extent of the base of the Chalk from 

 Hunstanton to Norwich, where it was perforated by a similar boring. 

 On this inclined plane of the Chalk, the strata were successively 



1 The flake in question is undoubtedly of human workmanship. See Geol. Mag. 

 1872, Vol. IX., p. 268.— Edit. Geol. Mag. 



