378 Geological Society: — 



thickness, and upon the top of this the Iron Amianthus occurred in 

 snow-white fibrous masses, the fibres radiating in a concentric 

 manner, and forming more or less botryoidal concretions, somewhat 

 resembling haematite in appearance, and separated by extremely 

 thin plates or septa of iron, by which the entire mass is divided into 

 irregular prisms of about half an inch in diameter. 



A similar product is described by Percy as occurring in the blast- 

 furnaces of the Harz, and is said to consist almost entirely of fibrous 

 silica, with a few specks of iron and graphite, and minute cubes of 

 nitro-cyanide of titanium. Both graphite and titanium occur in 

 the Wingeworth refuse ; the graphite is found in thin plates, the 

 nitro-cyanide of titanium in masses of crystals. 



Percy states that the origin of the Iron Amianthus is found in 

 the oxidation of the silicon, which is separated in greater or less 

 degree under the same conditions as graphite, and is oxidized at a 

 high temperature. 



May 28.— Prof. T. G. Bonney, l).Sc, F.R.S., President, 

 in the Chair. 

 The following communications were read : — 



1. " The Archaean and Lower Palaeozoic Rocks of Anglesey.'' By 

 Dr. C. Callaway, F.G.S. With an Appendix on some Rock-spe- 

 cimens, by Prof. T. G. Bonney, D.Sc, F.R.S., President G.S. 



The object of the author was to furnish additional proof of the 

 Archaean age of the altered rocks of the island. He held that the 

 Pebidian mass on the north was fringed by Palaeozoic conglomerates, 

 containing, amongst other materials, large rounded masses of lime- 

 stone, derived from the calcareous series on the north coast, these 

 conglomerates being probably a repetition by reflexed folding of 

 those which lie at the base of the Palaeozoic series. In like manner 

 conglomerates which margined the western (Holyhead) schistose area 

 contained angular pieces of altered slate undistinguishable from 

 some of the Pebidian rocks of the north-west. These conglomerates 

 dipped to the east, forming the western side of a syncline. Near 

 Llanfihangel were sections which showed not only the Archaean age 

 of the gneissic and slaty (Pebidian) groups, but also the higher 

 antiquity of the former. These conclusions were derived from the 

 occurrence of granitoid pebbles in the slaty series, and from the 

 presence of masses of the slate, as well as gneissic fragments, in 

 the basement Palaeozoic conglomerates. The author was at present 

 unable to accept the Cambrian age of the lower Palaeozoic rocks, 

 and considered that the fossils he exhibited tended to confirm the 

 views of the Survey on the correlation of those strata. The paper 

 concluded with a sketch of the physical geography as it probably 

 existed in Ordovician times. An Appendix furnished by Prof. 

 Bonney tended, by microscopic evidence, to confirm the proof fur- 

 nished by the paper. 



2. " On the new Railway-cutting at Guildford." By Lt.-Col. H. 

 H. Godwin-Austin, F.R.8., F.G.8., and W.Whitaker, Esq.,B.A., F.G.S. 



In this paper the authors described a section exposed in a new 



