Chapter 16 Collaborating on the Borrowdale Volcanics and the granites

Abstract

Abstract If working out a plausible story satisfactory to the majority of geologists was difficult for the Skiddaw Slates, and is probably still incomplete, things proved even more difficult for 'Otley II' and 'Otley IIP, as we shall shortly see. Getting an agreed mapping for the Borrowdale Volcanics, and an agreed interpretation as to the structure and history of the unit has proved to be the most controversial part of the whole story of Lakeland geology (though debates about 'Otley IIP were perhaps more current by 2000); and the work done on this part of the sequence spun off into the debates about the burial of nuclear waste described in Chapter 20. Yet the basic idea that the Ordovician volcanoes gave rise to the BVG as part of a system of arc volcanism, in accordance with orthodox plate-tectonic theory, was never a controversial issue, though not all have agreed as to whether the volcanism was or was not wholly subaerial. Even so, the method of dealing with the BVG proved controversial. So too have been the tectonic implications for the structure of the Lake District, the relationship of the ancient volcanoes to the emplacement of the granites, and the role of these in the geological history of the region. As for the Skiddaw Slates, the Surveyors were again first into the field in the examination of the BVG. The principal workers on the volcanics were Peter Allen, David Millward (see pp. 168 and 191), Eric Johnson, Michael Petterson and Brett Beddoe-Stephens