CONTENTS 
XV 
BOOK IV 
THE SILUEIAK VOLCANOES 
CHAPTER XH 
Characters of the Silurian System in Britain. The Arenig Volcanoes 
PAUE 
The Land and Sea of Silurian time — Classification of the Silurian System — General Petro- 
graiihy of the Silurian Volcanic Rooks — I. The Eruptions of Arenig Age . . 173 
CHAPTER XIH 
The Eruptions of Llandeilo and Bala Age 
1- The Builth Volcano — ii. The Volcanoes of Pembrokeshire — iii. The Caernarvonshire 
Volcanoes of the Bala Period — iv. The Volcanic District of the Berwyn Hills — v. 
The Volcanoes of Anglesey — vi. The Volcanoes of the Lake District ; Arenig to close 
of Bala Period — vii. Uj)per Silurian (?) Volcanoes of Gloucestershire . . . 202 
CHAPTER XIV 
The Silurian Volcanoes op Ireland 
. 239 
BOOK V 
THE VOLCANOES OF DEVONIAN AND OLD RED 
SANDSTONE TIME 
CHAPTER XV 
The Devonian Volcanoes . ....... 257 
CHAPTER XVI 
The Volcanoes of the Old Red Sandstone 
Geological Revolutions at the close of the Silurian Period — Physical Geography of the Old 
Red Sandstone — Old Lake-basins, their Flora and Fauna — Abundance of Volcanoes — 
History of Investigation. in the Subject . ...... 263 
