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 



