CHAP. VII 
PLAN OF THIS WORK 
107 
occupation. The l)lack Cuillins and the pale Eed Hills are solitudes left 
to the few wild creatures that have not yet been exterminated. The 
corries are the home of the red deer. The gabbro cliffs are haunts of the 
eagle and the raven. Where patches of soil have gathered in the crannies 
of^the gabbro, alpine plants find their home. In the chasms left by the 
decay of the dykes between the vertical walls of their fissures, the winter 
snows linger into summer, and conceal with their thick drifts the 
mouldering surface of the once molten rock beneath them. On every side 
and at every turn a mute appeal is made to the imagination by the strange 
contrasts between the quiet restfulness of to-day, when the sculpture-tools 
of nature are each busily carving the features of the landscape, and the 
tumult of the time when the rocks, now so silent, were erupted. 
Tlie general discussion of the subject of Volcanisni in this Introduction 
will, I hope, have prepared the reader who has no special geological 
training for entering upon the more detailed descriptions in the rest of this 
treatise” As already stated, the chronological order of arrangement will be 
followed. Beginning with the records of the earliest ages, we shall follow 
the story of volcanic action down to the end of the latest eruptions. 
Each great geological system will be taken as a whole, representing a 
long period of time, and its volcanic evolution will be traced from the 
beginning of the period to the close. Some variety of treatment is 
necessarily entailed by the wide range in the nature and amount of the 
evidence for the volcanic history of different ages. But where practicable, 
an outline will first be given of what can be gathered respecting the 
physical geography of each geological period in Britain. In the description 
which will then follow of the volcanic phenomena, an account of the 
general characters of the erupted rocks will precede the more detailed 
narrative of the history of the volcanic eruptions in the several regions 
where they took place. Eeferences to the publislied literature of each 
formation will be given in the first part of each section, or will be intro- 
duced in subsequent pages, as may be found most convenient. 
