The Origin of the Crystalline Schists of the Malvern Hills

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Abstract
I. Introduction The crystalline rocks of Malvern are of exceptional importance to the student of the problems of metamorphism, inasmuch as the causes in operation have acted with comparative feebleness, and thus have not obliterated the earlier stages of their work. Hence we are able in numerous sections to observe tho details of the process by which a massive igneous rock has been converted into a well-foliated schist. In my first paper on the subject, I gave an outline of the mode in which some of the schists had been formed. In the second, I described the most important mineral changes that occur at the zones of shearing. It now remains to work out certain structural details, to meet difficulties arising or suggested in the course of the enquiry, and to classify the chief varieties of schist in the light of their mode of origin. I would add that five years' study of these rocks has enlarged my belief in the efficacy of dynamo-metamorphism, to a degree which I should hardly have conceived possible when I presented my first paper to the Society in 1887. In the present communication, it will be unnecessary to refer to minerals which do not play an essential part in the metamorphic process. Apatite, for example, does not, so far as the writer has observed, undergo any change. Sphene, garnet, and rutile are probably secondary products; but the first and second have been noticed in No. II., while the last occurs in very inconspicuous

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