48 
SUCCESSION OF STRATA. 
regularly bedded, from having been depo¬ 
sited layer by layer in water, or of fine sand, 
or coarse gravel. 
The proof of their succession is derived 
from the fact of their dipping the one be¬ 
neath the other, like the tiles of a roof. 
The evidence of their order is that wherever 
any two members of a series occur, they in¬ 
variably occupy the same relative position. 
Thus the traveller who journeys from Lon¬ 
don to the Scottish border, to the Welch 
frontier, and to the Land’s End in Cornwall 
will in each case pass over different suites of 
rocks, some of which are altogether absent 
on each line; but wherever in more than 
one journey, the same kind of rocks or for¬ 
mations were visible, they would be found 
occupying the same position with regard to 
each other. 
The proof of separation and succession 
derived from mineral aspect, and from rela¬ 
tive position, is remarkably strengthened 
by an examination of the organic contents 
of the strata; a very casual survey of these 
will force upon the observer the wonderful 
truth that each layer of terrestrial substance 
