PREFACE 
XI 
after the notion had been abandoned by some Of his most distinguished 
contemporaries. But the error, though it died hard, was confessed at last 
even by Jameson. 
After the close of this protracted and animated controversy the study 
ot former volcanic action resumed its place among the accepted subjects 
of geological research. From the peculiarly favourable structure of the 
country, Britain has been enabled to make many important contributions 
to the investigation of the subject. T)e la Beche, Murchison and Sedgwick 
led the way in recognizing, even among the most ancient stratified forma- 
tions of England and Wales, the records of contemporaneous volcanoes and 
of their subterranean intrusions. Scrope threw himself with ardour into 
the study of the volcanoes of Italy and of Central France. Maclaren 
made known the structure of some of the volcanic groups of the lowlands of 
Scotland. Eamsay, Selwyn, and Jukes, following these pioneers, were the 
first to map out a Palajozoic volcanic region in ample detail. Sorby, apply- 
ing to the study of rocks the method of microscopic examination by thin 
slices, devised by William Nicol of Edinbirngh for the study of fossil plants, 
opened up a new and vast field in the domain of observational geology, and 
furnished the geologist with a key -to solve many of the problems of vol- 
canisin. Thus, alike from the stratigraphical and petrographical sides, the 
Igneous rocks of this country have received constantly increasing attention. 
The present work is intended to offer a summary of what has now been 
ascertained regarding the former volcanoes of the British Isles. The 
subject has occupied much of my time and thought all through life. 
01 n among the crags that mark the sites of some of these volcanoes, I was 
led in my boyhood to interest myself in their structure and history. The 
fascination which they then exercised has lasted till now, impelling me to 
make myself acquainted with the volcanic records all over our islands, 
and to travel into the volcanic regions of Europe and Western America for 
the purpose of gaining clearer conceptions of the plienomena. 
Fioni time to time during a period of almost forty years I liave com- 
municated chiefly to the Geological Society of London and the Eoyal Society 
of Ediubiu'gh the residts of my researches. As materials accumulated, the 
esire arose to combine them into a general narrative of the whole progress 
of volcanic action from the remotest geological periods down to the time 
when the latest eruptions ceased. An opportunity of partially putting this 
esign into execution occurred when, as President of the Geological Society, 
le duty devolved upon me of giving the Annual Addresses in 1891 and 
89..J. Within the limits permissible to such essays, it was not possible to 
Piesent more than a full summary of the subject. Since that time I have 
ontinued my researches in the field, especially among the Tertiary vol- 
