Charnwood Forest, since 1891, the date of the last paper by Canon E. Hill and myself, has been investigated by the Geological Survey. Though part of their map and the accompanying memoir have not yet been published, the general results of their work have been announced by Professor W. W. Watts, by whom most of it was executed. As we stated at the time, we were far from being satisfied with some important points in our own conclusions; so that since my return to Cambridge I have studied my specimens and slices from the north-western region, which had presented to us the more serious difficulties. In 1891 I had been led to regard the characteristic rocks of Peldar Tor and High Sharpley as lava-flows, but considered the dominant rocks of Bardon Hill to be mainly pyroclastic. Professor Watts, however, maintained the intrusive character of the first and second, while taking the same view as myself about the third. The lava-flow hypothesis had appeared to me the more probable, because I doubted whether a mass so large as the Peldar-Bardon porphyroid, if intrusive, could have maintained throughout a texture so uniformly fine-grained, and I had found in the Bardon quarries fragments of it embedded in rock which I then supposed to be a somewhat altered tuff, closely related to the High Sharpley lava.
U.S. Geological Survey (USGS) Western Region; Santa Barbara Channel Coastal and Ocean Science