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imagine any circumftances in which this firatum mufl not be 

 conceived of a much greater extent than the very circumferibed 

 furface of the qnarries of Bolca. Of fuch a ftratum then, thefe 

 quarries are evidently to be confidered as no more than portions 

 or fragments, now completely disjoined from all connedion with 

 their native bed : We are n^xt to enquire how thefe portions 

 may have been fo detached. 



A NUMBER of clrcumflances already mentioned leave not a 

 doubt, that this muft have happened after the confolidation of the 

 original ftratum ; for it is clear, that a disjundion of this. kind, 

 could not have taken place, in any way, without fuch a concuf^- 

 lion and difturbance of thefe maffes, as, if their matter was in 

 any refped foft or yielding, or in any other than a firmly com- 

 paded ftate, muft have greatly difarranged their laminar flrucr 

 ture, a& well as the forms of the fifli contained. Their extre- 

 mities too, inflead of being fharp and even, would have been 

 left confufed and ill-defined. This matter, therefore, muft cer- 

 tainly have lain in its firft bed and pofition, undifturbed, fo 

 long at ieafl: as was neceffary to its perfed confolidation. At 

 fome period fubfcquent to this, it would feem that the whole of 

 the ftratum was violently broken up, and immenfe fragments 

 of it heaved from their natural fituation, and difperfcd here and 

 there, as in the inftance before us. But when we calculate the 

 prodigious forces required to produce the efFeds here defcribed, 

 we ftiall not find it eafy to aflign any other caufe, fully adequate 

 to them, but that which we have already had recourfe to, 



namely y 



