Page:Quarterly Journal of the Geological Society of London, vol. 25.djvu/530

406 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [June 23, should be remembered that the surfaces of basaltic rocks are very susceptible of decay. Discussion.

Mr. Etheridge remarked on the similarity of the Oolitic specimens to those from the Cotteswold Hills, and also to those from the Holy Land. Similar fossils also occurred in the far east, and even in Australia.

The President remarked that this range was not greater than that of some recent species; and in answer to his inquiry, Mr. Blanford stated that there were no marks of glaciation discernible in Abyssinia, the excavation of the valleys being apparently due to the excessive rainfall.

5. On the Graphite of the Laurentian of Canada. By Prof. J. W. Dawson, LL.D., F.R.S., F.G.S.

(The publication of this paper is postponed.)

[Abstract.]

The author described the modes of occurrence of great quantities of graphite in the Laurentian limestones of Canada. It occurs both in beds and veins, the latter generally not true fissures, but shrinkage- cracks or segregation-veins. It is also disseminated, in scales &c., through the substance of the rocks. The graphitiferous rocks are widely spread, both in Canada and the neighbouring portion of the United States. The author discusses the origin of this graphite, which he ascribes to the conversion of the remains of plants into bituminous matter, from which the graphite has in its turn been derived. In some cases he has found traces of fibres which he thought might be the remains of terrestrial plants. In conclusion the author referred to the interest attaching to this matter in connexion with the study of the conditions prevailing at the time of the deposition of these limestones, and especially as furnishing evidence of an abundance of vegetable life in the "Eozoic" period.

Discussion.

Prof. Brayley inquired whether there was any proof that the substance called graphite might not be anthracite. He did not himself know of any instance of the passage of one of those substances into the other, and regarded graphite as of chemical origin, and not as directly derived from vegetable matter.

Mr. Mallet did not think that it was possible for any organic forms to remain in a substance so purely crystalline as typical graphite. The presence of organic remains was an argument in favour of the masses mentioned in the paper being lustrous anthracite rather than graphite.