CHAP. I 
PLAN OF THE WORK 
9 
this question. I shall try to show the nature and relative import- 
ance of the records of ancient volcanoes ; how these records, generally so 
fragmentary, may he pieced together so as to he made to furnish the 
history which they contain ; how their relative chronology may bo estab- 
lished ; how their testimony may be supplemented in such wise that the 
position of long vanished seas, lands, rivers, and lakes may be ascertained ; 
*ind how, after ages of geological revolution, volcanic rocks that have lain 
long buried under the surface now inlluence the scenery of the regions 
where they have once more been exposed to view. 
From this groundwork of ascertained fact and reasonable inference, we 
shall enter in Book 11. upon the story of the old volcanoes of the British Isles. 
It is usual to treat geological history in chronological order, beginning with 
the earliest ages. And this method, as on the whole the most convenient, 
will be adopted in the present work. At the same time, the plan so per- 
sistently followed by Lyell, of working backward from the present into 
the past, has some distinct advantages. The volcanic records of the later 
are much simpler and clearer than those of older times, and the 
student may, in some respects, profitably study the history of the Tertiary 
®>’uptions before he proceeds to make himself acquainted with the scantier 
chronicles of the eruptions of the Balfcozoic periods. But as I wish to 
follow the gradual evolution of volcanic phenomena, and to show how vol- 
canic energy has varied, waxing and waning through successive vast intervals 
of time, I will adhere to the chronological sequence. 
