Note 161 — Chapter XII · CHARACTERS OF THE SILURIAN SYSTEM IN BRITAIN. THE ARENIG VOLCANOES
Reading edition
Silurian System (1839), chap. xix.; Siluria, 4th edit. (1867), pp. 26, 49.
[162] Proc. Liverpool Geol. Soc. x. (1854), p. 62.
[163] Geol. Mag. (1887), p. 78.