io8 
THE TERTIARY VOLCANOES 
BOOK VIII 
records of the long array of geological periods over which it was spread 
show that the biological evolution advanced through a vast series of species, 
genera and orders which one by one appeared and disappeared. 
The ages that elapsed between the final dying out of the Palaeozoic 
volcanoes and the outburst of those of Tertiary time were so protracted that 
many revolutions of the geography of Europe were comprised within them. 
Land and sea changed places again and again. First came the singular 
topography of the Trias, which prolonged and accentuated the characteristics 
ot the closing Paheozoio ages. Next arose the more genial climate and 
more varied geography of the, Jurassic period, when comparatively shallow 
seas overspread the site of most of the European continent, and tracts of old 
land stretched away to the west and north. Another crowded succession 
of changes in the disposition of land and sea filled the long Cretaceous 
period, at the close of which a more rapid and complete transformation in 
European geography took place. 
Yet during all these transitions and vicissitudes, so far as we know, 
volcanic energy remained quiescent throughout Western Europe. It was 
not until some time after the great terrestrial movements that raised so 
much of the Cretaceous sea-floor into land, and laid the foundations of the 
modern continent, that the subterranean fires once more awoke to vigorous 
action. 
The renewal ot eruptions in the early ages of Tertiary time was as wide- 
spread as it was energetic. Over many regions of the European continent 
volcanoes broke out either in new areas or on old sites. For the most part 
they appeared as scattered puys or as Vesuvian vents, generally not of the 
first magnitude, like those of Central France, Hungary, Wiirtemburg and 
Italy. But in the north-west they assumed more colossal proportions, and 
took the form of fissure-eruptions by which many thousands of square miles 
of country were deluged with lava. From the South of Antrim all along the 
West of Scotland to the north of the Inner Hebrides remains of these basalt- 
floods form striking features in the existing scenery. The same kind of rocks 
reappear in the Faroe Islands and in Iceland, so that an enormous tract 
of North-western Europe, much of it now submerged under the sea, was the 
scene of activity of the Tertiary volcanoes. In entering, therefore, upon a 
consideration of the British Tertiary volcanic rocks, we are brought face to 
face with the records of the most stupendous succession of volcanic pheno- 
mena in the whole geological history of Europe. Fortunately these records 
have been fully preserved in the British Isles, so that ample materials 
remain there for the elucidation of this last and most marvellous of all tire 
volcanic epochs in the evolution of the continent. 
As the remains of the Tertiary series of volcanic eruptions are the 
youngest of all the volcanic records of Britain, they are naturally the 
freshest and most abundantly preserved. They consequently reveal with 
singular clearness multitudes of volcanic phenomena that are less distinctly 
recognizable, or not to be found at all, among the Palaeozoic systems. Hence 
they will be discussed in greater detail in the following chapters. 
