The Ancient Volcanoes of Great Britain, Volume 1 (of 2)Note 167 — Chapter XII · CHARACTERS OF THE SILURIAN SYSTEM IN BRITAIN. THE ARENIG VOLCANOESReading editionAfter Prof. Lapworth and Mr. Watts, op. cit. p. 342.◇Copy noteReturn to CHAPTER XII CHARACTERS OF THE SILURIAN SYSTEM IN BRITAIN. THE ARENIG VOLCANOES