The Skiddaw Granite and its Metamorphism

I. I ntroduction . T he main object of this paper is the investigation of the alteration of the sedimentary rocks of the Skiddavian Series by the intrusion of the mass of igneous rock which is commonly known as the Skiddaw granite. One or two cognate subjects will be touched upon, such as the composition and petrographical character of the intrusion, and the general structure and tectonic relations of the sedimentary series; but, in the main, the paper is a study in metamorphism. The Skiddavian Series includes rocks of varying lithological character, grits, flags, shales, and slates, so that the products of metamorphism are not by any means uniform in character; and, in addition to this, the problem is complicated by the occurrence throughout the area of a varying though generally high degree of folding and cleavage. Hence it is necessary to study the effects of thermal metamorphism superposed upon those of a previous dynamic metamorphism. During my examination of the Buttermere and Ennerdale granophyre, I was naturally led to study the effects of this intrusion on the surrounding rocks, which are well-marked. This subject proved to be an unusually difficult one and I then turned my attention to the metamorphism of the Skiddaw intrusion, in the hope that this would throw some light on the puzzling phenomena presented in the former case. It seemed advisable, therefore, to make a complete study of the Skiddaw metamorphism; and since this latter is in itself the more important case, and probably the more instructive from