the Siebengebirge " 117

" 22. Section of Extinct Crater of the Roderberg " 120

" 23. Plan and Section of the Laacher See " 122

" 24. Extinct Craters in the Jaulan " 130

" 25. Mount Shasta " 139

" 26. Forms of Volcanic Tuff-Cones, Auckland " 148

" 27. "The White Rocks," Portrush, Co.
Antrim " 157

" 28. Section across the Volcanic Plateau
of Antrim " 159

" 29. Section at Templepatrick " 161

" 30. Cliff above the Giant's Causeway " 163

" 31. The Giant's Causeway, Co. Antrim " 165

" 32. "The Chimneys," North Coast of
Antrim " 166

" 33. Section at Alt na Searmoin, Mull " 175

" 34. View of the Scuir of Eigg from the East " 181

Map of Volcanic Band of the Moluccas " 200

" 35. Map of the Krakatoa Group of Islands " 203

" 36. Section from Verlaten Island through
Krakatoa " 204

Fig. 37. Isoseismals of the Charleston Earthquake _Page_ 223

" 38. Photograph of the Moon's Surface " 241

" 39. Portion of the Moon's Surface " 243

_PLATES._

I. & II. Magnified Sections of Vesuvian Lavas.

III. & IV. Magnified Sections of Volcanic Rocks.

Volcanoes: Past and Present.

PART I.

INTRODUCTION.

CHAPTER I.

HISTORIC NOTICES OF VOLCANIC ACTION.

There are no manifestations of the forces of Nature more calculated to
inspire us with feelings of awe and admiration than volcanic eruptions
preceded or accompanied, as they generally are, by earthquake shocks.
Few agents have been so destructive in their effects; and to the real
dangers which follow such terrestrial convulsions are to be added the
feelings of uncertainty and revulsion which arise from the fact that the
earth upon which we tread, and which we have been accustomed to regard
as the emblem of stability, may become at any moment the agent of our
destruction. It is, therefore, not surprising that the ancient Greeks,
who, as well as the Romans, were close observers of the phenomena of
Nature, should have investigated the causes of terrestrial disturbanc