Ch. XXIIL] 
WHY MORE DISTURBED. 
335 
entitling us to resort to any hypothesis respecting an original 
distinctness in the degree of lapidifi cation of the secondary 
strata. 
Secondary rocks why more disturbed. — As the older forma- 
tions are generally more stony, so also they are more fractured, 
curved, elevated, and displaced, than the newer. Are we, then, 
to infer, with some geologists, that the disturbing forces were 
more energetic in remoter ages ? No conclusion can be more 
unsound ; for as the moving power acts from below, the newer 
strata cannot be deranged without the subjacent rocks par- 
ticipating in the movement ; while we have evidence that the 
older have been frequently shattered, raised, and depressed, 
again and again, before the newer rocks were formed. It is 
evident that if the disturbing power of the subterranean causes 
be exerted with uniform intensity in each succeeding period, 
the quantity of convulsion undergone by different groups of 
strata will generally be great in proportion to their antiquity. 
But exceptions will occur, owing to the partial operation of the 
volcanic forces at particular periods, so that we sometimes find 
tertiary strata more elevated and disturbed, in particular coun- 
tries, than are the secondary rocks in others. 
Some of the enormous faults and complicated dislocations of 
the ancient strata may probably have arisen from the continued 
repetition of earthquakes in the same place, and sometimes from 
two distinct series of convulsions, which have forced the same 
masses in different, and even opposite directions, sometimes by 
vertical, at others by horizontal movements. 
Secondary volcanic rocks of different ages. — The association 
of volcanic rocks with different secondary strata is such as to 
prove, that there were igneous eruptions at many distinct 
periods, as also that they were confined during each epoch, as 
now, to limited areas. Thus, for example, igneous rocks con- 
temporaneous with the carboniferous strata abound in some 
countries, but are wanting in others. So it is evident that the 
bottom of the sea, on which the oolite and its contemporary 
deposits were thrown down, was, for the most part, free from 
