On the Chemical Geology of the Malvern Hills

Abstract

I n the year 1861, I commenced an examination of the rocks composing the Malvern Hills; and the results of the analyses of some of the eruptive rocks, taken from various parts of the chain, were published in the Edinburgh New Philosophical Journal, vol. xv. pp. 1–7. Since then, a minute and accurate description of the structure of these hills has been given by my friend Dr. Harvey B. Holl (Quart. Journ. Geol, Soc. vol. xxi. p. 72), to which I shall have to refer, in the course of this paper, for a more particular account of the physical geology of the district under investigation. I have also had the advantage of visiting the hills with him, and, with his assistance, I have been able to make many valuable additions to my collection of specimens of the various rocks for analysis. In the present communication I propose to examine the rocks with a view to the discovery of the sources from which they have been derived, and the chemico-physical processes which have resulted in their development, confining myself more especially to the consideration of those which appear to be, wholly or in part, the products of eruptive action, whether they occur as intrusive masses, lava-flows, or beds of ash mechanically deposited. Those of which the materials were originally furnished by the decomposition and disintegration of other rocks, and the nature of the metamorphic influences to which they have been subsequently exposed, I hope to investigate in another paper. I. Lava and