PREFACE 
In 110 depiirtiiieiit of science is the slow and chequered progress of investiga- 
tion more conspicuous than in that branch of Geology which treats of 
volcanoes. Although from tlie earliest dawn of history, men had been 
familiar with the stupendous events of volcanic eruptions, they were 
singularly slow in recognizing these phenomena as definite and important 
parts of the natural history of the earth. Even within the present century, 
the dominant geological school in Europe taught that volcanoes were mere 
accidents, due to the combustion of subterranean beds of coal casually set 
on fire by lightning, or by the decomposition of pyrites. Ihirning mountains, 
as they were called, were believed to be only local and fortuitous appearances, 
depending on the position of the coal-fields, and having no essential con- 
nection with the internal structure and past condition of our planet. So long 
as such fantastic conceptions prevailed, it was impossible that any solid 
progress could be made in this branch of science. A juster appreciation of 
the nature of the earth’s interior was needed before men could recognize 
that volcanic action had once liecn vigorous and prolonged in many countries, 
where no remains of volcanoes can now be seen. 
I’o France, which has led the way in so many ilepartments of huinaii 
inquiry, belongs the merit of having laid the foundations of the systematic 
study of ancient volcanoes. Her groups of Puys furnished the earliest 
inspiration in this subject, and have ever since been classic ground to which 
the geological pilgrim has made his way from all parts of the world. As 
far back as the year 1752, Guettard recognised that these marvellous hills 
were volcanic cones that had poured forth streams of lava. But it was 
leserved tor Desmarest twelve years later to examine the question in detail, 
and to establish the investigation of former volcanic action upon a broad 
and firm basis of carctirl observation and sagacious inference. His method 
of research was as well conceived as the region of Auvergne was admirably 
fitted to be the field of exploration. He soon discovered that the volcanoes 
