PROCEEDINGS OF GEOLOGICAL SOCIETIES. 
307 
been filled with ore prior to the great spread of deposits of red and brown iron- 
ore which took place in S.AV. England and South Wales soon after the dejiositionof 
the coal-nieasiires. 
The interest attached to these pseudomorphous changes, and to the scale on 
which thoy have taken place, is heightened by comparison with the ores of Siegen, 
of Somniorostro near Bilboa, and those brought by Dr. Livingstone from Central 
Africa. 
4. " On Native Copper in the Llandudno Mines, near Great Orme's Head, North 
Wales." By Capt. W. Vivian, of the Llandudno Mine. Communicated by J. 
Taylor, Esq.", F.G.8. 
The author described some microscopic arborescent crystallizations of native 
copper occurring with ruby copper in small cavities in a brown limestone, which 
contains yellow bisulphuret of copper. Harder sulphurous ore occurs in the bed 
below, and carbonates and oxides of copper in the bed above. The arborescent 
copper is jirobably the result of the decomposition of copper ores, and has been 
formed sulisequently to the crystals of lime in the limestone, which are often 
tipped with an oetahedi'on of ruby-oxide, or overlaid with spikes of the native 
copper. 
5. "On the Slate-rocks and Trap-veins of Easdale and Oban." By Professor 
James Nicol, F.G S. 
The author first described the mineral characters of the clay slate of the Islands 
of Easdale and Seil, and noticed the iron-pyrites and the veins of calc-spar and of 
quartz occurring in the slate as well as gritty and calcareous strata that are detected 
as interstratified with the more highly cleaved beds of the slate ; also some soft car- 
boniferous beds and some hard calcareous nodules, imbedded in the slate. In one 
of these nodular masses, at a depth of 140 feel from the surface, a small quantity 
of bitumous coal was stated to have been lately found. Fucoidal or annelidal 
markings occasionally appear in the slates. Professor Kicol then described the 
original but obscure stratification of the Easdale slate, which, with care, is seen 
to present beds disposed in undulations, and, where most clearly seen, dip at a 
high angle to the west or north-west. Near Olian, and along the Sound of Kcrrer.a, 
the stratification is more distinct, and the strata are very much contorted. The 
slaty cleavage of the district was then treated of in detail. Its average strike 
varies 20° from that of the beds ; and the direction of strata and cleavage-planes 
have evidently a connection with the more ancient and deep-seated causes which 
have produced the most striking features in the conSguration of the country ; they 
are nearly parallel to the shores of Loch Linnhe, to the Island of Lismore, and to 
the great depi-essions occupied by Loch Etivo, Loch Awe, and Loch Fyne. The 
trap-veins of Easdale and Oban were nest described, especially a pitch-stone at 
Seil ; and were shown to be of three periods. At least two sets of the veins 
appear to bo of a date subsequent to the Jurassic period ; and the author remarked, 
as an instance of the vei'y recent date of many of the great convulsions by which 
the present jihysical outline of Scotland has been produced, that the mountain- 
clifF, 1,200 to i,500 feet high, forming the coast of Morne, between Ardtornish 
and Loch Linnhe, consists in half of the old gneiss, in half of lias-strata and 
recent trap, brought side by side with each other along an enormous fault, and 
now smoothed down into one uniform mass. In conclusion, Professor Nicol 
stated that he considered tlie Easdale slate to be of Lower Silurian age, but 
younger than the slates of Birnam and Dunkeld. 
Specimens illustrative of the several papers were exhibited ; also a series of 
North American fo.ssils collected, described, and presented by Professor Jules 
Marcou of Zurich. 
> 
SWINET liECTrRES OX GEOLOaT, IN CONNECTION ^VITH THE BhITISH JIUSEFM. — 
This annual course of twelve lectures was commenced by Dr. A. G. Melville, Professor 
of Natural History in the Queen's University, Ireland, at the Museum of Practical 
Geology, Jermyn-street, on the 14th of June, and delivered as follows : — June 14th, 
Subject-matter of Geology; Classes of liocks. 15th, Composition of Rocks; 
