GEOLOGY 
through the site of Keswick. But we have no further evidence upon 
this point than the analogy afforded by the behaviour of volcanoes at the 
present day, and the fact that volcanoes of the same period occur also in 
Wales. 
After the first violent paroxysm and the discharge of fragments of 
sedimentary rock into the air, the relief of pressure below the surface 
appears to have favoured the liquefaction of the rock. Under these 
conditions, that heated mixture of the component gases of water and 
liquefied rock of which lavas consist, began to make its way to the sur- 
face. But the explosive forces pent up below were so vastly more 
powerful than was needed for merely propelling the fluid mass to the 
surface, that they sufficed, each time the pressure was relieved, to drive 
the fluid rock with terrific violence to a great height—probably miles— 
into the air, whence, as the force expended itself and gravitation came 
more into play, the coarser fragments of lava, now hardened by their 
passage through the cool air, fell back in great piles upon the surface, 
close to the orifice whence they were ejected, while the finer material 
was distributed far and wide by the action of the wind. 
The evidence shows that a succession of such explosive outbursts 
took place, with pauses of varying length between each, during which 
marine sediments were deposited here and there to a small thickness 
between such of the volcanic mounds as reached to no great height 
above the sea. 
Eventually the eruptions occasionally assumed a less violent char- 
acter, and on these occasions a quiet outpouring of lava took place, 
followed in turn by more explosive outbursts and the dispersal of frag- 
mentary material over an increasingly large area. There can be but 
little doubt that the central area of volcanic action soon rose to a suffi- 
cient height to stand well above the waves, and that it probably con- 
tinued to maintain that elevation while the additions to the surface of 
the volcano kept pace with the depression caused by the general subsi- 
dence which set in at an early stage. ; 
(2) Several minor events occurred in connection with the central por- 
tion of the volcano, some of which have to be noticed here. Amongst 
the effects of these may be mentioned the curious ‘ faulting’ so well seen 
in some of the Cumberland ‘green slates,’ and also the crumpling and 
contortion that accompanies these ‘ faults.’ Both appear to be due to 
the fact that a period during which fine volcanic dust was ejected was 
followed by another when floods of molten rock poured over the sides of 
the crater and down the slopes of the cone, the flood of lava thus rolling 
over the lately-deposited tuff. The effect upon these unconsolidated 
beds of rock fragments was naturally to produce the same result as if 
a gigantic road-roller had passed over them. The beds were folded, 
crumpled and fractured, and, being compressed obliquely downwards, 
the faults generally took the form of reversed faults. Thrusts due to the 
flow of the lavas affected the tuffs beyond the lava flows themselves, and 
it therefore frequently happened that a bed of tuff which had been frac- 
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