Supplementary Notes on the Metamorphic Rocks around the Shap Granite

Open Access
Publisher Website
Google Scholar
Abstract
I. Introduction. In a paper presented to this Society two years ago we described at some length the phenomena of metamorphism exhibited by the various volcanic and sedimentary rocks around the Shap Granite. Since that time re-examination of some of the rocks, in the light of what we have seen in other parts of the Lake District, has enabled us to make certain corrections and additions to our work ; and we now offer these with the intention of rendering the description of the metamorphism in some measure more complete. The chief correction we have to make relates to the volcanic rocks on the northern side of the granite, which we formerly classed with the intermediate rocks (andesitic lavas and ashes) seen to the west of the granite. We now find that they constitute a distinct group of more basic composition. To such a conclusion, indeed, we should have been led by the low silica-percentages of some metamorphosed specimens from Low Fell,² a fact which we contented ourselves with recording as inexplicable on the supposition that the rocks had been originally similar to the Stockdale andesites. We have since learnt that basic lavas are very widely distributed over the Lake District, and that the recks on the northern side of the Shap Granite must be placed in this division. They may with propriety be named basalts, although, on account of the absence of olivine, some petrographers would prefer to call them basic andesites. Since our description of the metamorphosed intermediate

This publication has 0 references indexed in Scilit: