52 PRIMARY STRATIFIED ROCKS. 
out those lowest portions of these strata, which 
have been called primary, is a fact consistent 
and mica slate in a less degree, the same action of which the 
maximum intensity produced granite. 
'^ The dislocations and deranged position of the strata he 
attributes to the breaking in of vast vaults, which the vesicular 
and cavernous structure assumed by masses, during their re- 
frigeration from a state of fusion must necessarily have occasioned 
in the crust, thus cooling down and consolidated. He assigns 
the weight of the materials and the eruption of elastic vapours as 
the concurrent causes of these disruptions ; to which we should 
perhaps add, that the oscillations of the surface of the still fluid 
nucleus may, independently of any such cavities, have readily 
shattered into fragments the refrigerated portion of the crust ; 
especially, as at this early period, it must have been necessarily 
very thin, and resembling chiefly the scoriae floating on a surface 
of lava just beginning to cool. He justly adds, that these dis- 
ruptions of the crust must, from the disturbances communicated 
to the incumbent waters, have been necessarily attended with 
diluvial action on the largest scale. When these waters had 
subsequently, in the intervals of quiescence between these 
convulsions, deposited the materials first acquired by their force 
of attrition, these sediments formed, by their consolidation, 
various stony and earthy strata. Thus, he observes, we may 
recognize a double origin of the rocky masses, the one by 
refrigeration from igneous fusion, (which, as we have seen, he 
considered principally to be assignable to the primary and 
fundamental rocks,) the other by concretion from aqueous 
solution. We have here distinctly stated the great basis 
of every scientific classification of rock formations. By the 
repetition of similar causes (i. e. disruption of the crust and con- 
sequent inundations) frequent alternations of new strata were 
produced, until at length these causes having been reduced to a 
condition of quiescent equilibrium, a more permanent state of 
things emerged. Have we not here clearly indicated the data 
on which, what may be termed the chronological investigation of 
the series of geological phenomena, must ever proceed V 
