Chap. IX. 
GEOLOGICAL KECOED. 
285 
having been much struck with the evidence of denuda¬ 
tion, when viewing volcanic islands, which have been 
worn by the waves and pared all round into perpendicular 
cliffs of one or two thousand feet in height; for the 
gentle slope of the lava-streams, due to their formerly 
liquid state, showed at a glance how far the hard, rocky 
beds had once extended into the open ocean. The 
same story is still more plainly told by faults,—those 
great cracks along which the strata have been upheaved 
on one side, or thrown down on the other, to the 
height or depth of thousands of feet; for since the crust 
cracked, the surface of the land has been so completely 
planed down by the action of the sea, that no trace of 
these vast dislocations is externally visible. 
The Craven fault, for instance, extends for upwards 
of 30 miles, and along this line the vertical displace¬ 
ment of the strata has varied fron 600 to 3000 feet. 
Prof. Eamsay has published an account of a downthrow 
in Anglesea of 2300 feet; and he informs me that he 
fully believes there is one in Merionethshire of 12,000 
feet; yet in these cases there is nothing on the surface 
to show such prodigious movements; the pile of rocks 
on the one or other side having been smoothly swept 
away. The consideration of these facts impresses my 
mind almost in the same manner as does the vain en¬ 
deavour to grapple with the idea of eternity. 
I am tempted to give one other case, the well-known 
one of the denudation of the Weald. Though it must 
be admitted that the denudation of the Weald has been 
a mere trifle, in comparison with that which has 
removed masses of our palaeozoic strata, in parts ten 
thousand feet in thickness, as shown in Prof. Ramsay’s 
masterly memoir on this subject: yet it is an admir¬ 
able lesson to stand on the intermediate hilly country 
and look on the one hand at the North Downs, and 
