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I.—A Case of Metamorphism of Chalk

Published online by Cambridge University Press:  01 May 2009

Geo. C. Gough
Affiliation:
Professor of Natural History, Royal Agricultural College, Cirencester.

Extract

Cases of metamorphosed limestones where the calcium carbonate has been converted by contact with some igneous magma into a calc-silicate rock are by no means rare, one of the best known being the conversion of the Coniston Limestone of the Lake District by the Shap Granite into a rock with various calc-silicate and other minerals such as Wollastonite, Omphacite, etc., as described by Messrs. Harker and Marr. But as far as I know, no case has been recorded where ordinary white chalk has been similarly changed. Dr. Hibsch describes a case of baculite marl containing Foraminifera which has been altered by contact with dolerite. The Foraminifera disappear and the rock becomes a granular limestone with epidote, forming a calc-silicate hornstone. This seems the nearest case to the alteration in co. Antrim I am about to describe.

Type
Original Articles
Copyright
Copyright © Cambridge University Press 1907

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References

page 145 note 1 Q.J.G.S., 1891.

page 145 note 2 Verhandlungen Geol. Reichsanstalt, 1889, p. 204.

page 145 note 3 Trans. G. S., vol. iii.

page 148 note 1 Q.J.G.S., vol. liii (1897).