Note 109 — Chapter XI · THE CAMBRIAN VOLCANOES OF NORTH WALES, THE MALVERN HILLS AND WARWICKSHIRE

The sections in the Vale of Llanberis on either side of Llyn Padarn have been again and again described and fought over. Some of the papers are cited in the following pages, but it would be impossible in this volume to find room for a full discussion of the differences of opinion. What is stated in the text is the result of my own study of the rocks on the ground, coupled with a careful consideration of the work of other observers.

[110] I can find no evidence of unconformability beneath any of the conglomerates. The section described by Professor Green, Quart. Journ. Geol. Soc. vol. xli. (1885), p. 74, merely shows the difference between the effects of cleavage on the fine tuffs and the more massive resisting conglomerate which overlies them. This section is represented in Fig. 43. At first sight the conglomerate appears to be lying on the vertical edges of an older group of slates, but any one acquainted with cleavage can trace this structure from the tuffs into the conglomerate and resuming its course again in the finer sediments above. The whole series of deposits in the section is continuous and conformable. The section on the slate railway has deceived Mr. Blake as well as Professor Green (Quart. Journ. Geol. Soc. vol. xlix. (1893), p. 445). The correct interpretation is given by Professor Bonney and Miss Raisin (op. cit. vol. l. p. 592).