PRIMARY SRATIFIED ROCKS 49 



detritus thus swept from the earliest lands into the most 

 ancient seas, we view the commencement of that enormous 

 series of derivative strata which, by long continued repeti- 

 tion of similar processes, have been accumulated to a thick 

 ness of many miles.* 



* Mr, Conybcare (in his admirable Report on Geology to the British As- 

 sociation for the advancement of Science, 1832, p. 367) shows, that many 

 of the most important principles of the igneous theory, which has been al- 

 most demonstrated by modern discoveries, had been anticipated by the uni- 

 versal Leibnitz " In ihc fourth section of his Protogaea, Leibnitz presents 

 us with a masterly sketch of his general views, and, perhaps, even in the 

 present day, it would be difficult to lay down more clearly the fundamental 

 positions which must be necessarily common to every theory, attributing 

 geological phenomena in great measure to central igneous agency. He 

 attributes the primary and fundamental rocks to the refrigeration of the 

 crust of this volcanic nucleus; an assumption which well accords with the 

 now almost universally admitted igneous origin of the fundamental granite, 

 and with the structure of the primitive slates, for the insensible gradation 

 of these formations appears to prove that gneiss must have undergone in a 

 greater, and mica slate in a less degree the same action of which the inaAi 

 rnuni 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 struc- 

 ture assumed by masses, during their refrigeration 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 tlie concurrent causes of tlicse 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 tliin, and resembling chiefly the 

 seorisc floating on a surface of lava just beginning to cool. He justly adds, 

 that these disruptions of the crust must, from the disturbances commmiv 

 cated 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 

 tirst acquired by their force of attrition, these sediments formed, by their 

 consolidation, various stony and earthy strata. Thus, he observes, we may 

 recognise a double origin of the rocky masses, the one by refrigeration from 

 iffneous fusion, (whicii, as we have seen, he considered principally to be us- 



VOL. I. — 5 



