118 ANCIENT BEACH AND DILUVIUM. 
being referrible to an zra more ancient than that to 
which the former can be ascribed ; and in short, it 
leaves with other reasons, grounds for consigning 
the beach to the same epoch as that wherein the 
forests now submerged and containing proofs (as 
Mr. De la Beche acknowledges) of belonging to the 
present zra, flourished. In truth, admirable as is 
the “ Geological Manual” as a book devoted to a 
consideration of facts, and the more valuable as 
being destitute of a leading theory, its author has 
overlooked the necessity of making local facts 
accord together in respect of time, and making 
them harmonize so far as possible and to the 
needful extent with the general geology both of 
this country and of the whole world. Accordingly, 
superior as Mr. De la Beche’s reasonings are to the 
generality ofmens’, he appears to me from this anxiety 
to provide a special theory for every case and to 
the exclusion of general considerations to have de- 
parted occasionally from his rule of careful induction. 
It must be confessed however, that the discrimina- 
tion of ancient beach from those deposits referrible 
to sudden oceanic ingress, or to the action of waters 
overspreading and devastating the land, is far from 
easy,—their characters so often approximate, they 
are so often situated near together without pre- 
senting defined characteristics, they would both 
for instance be accumulated greatly in hollows, clay 
might perchance escape into the substance of the 
former structure, and as previously intimated, not 
only would diluvium-occur at alvariety of elevations, 
but likewise ancient beach might in the progressive 
rise of the tide to which it is ascribable, be accu- 
mulated at a variety of heights above the present 
sea-mark. So complex are Nature’s operations in. 
the department of geology, so approximating and 
interchangeably associated the features of the 
various substances and phenomena she presents. 
