7HEORT of the EARTH. 225 



PART II. 



An Invefligation of the Natural Operations employed in confolidating 

 the Strata of the Globe. 



THERE are juft two ways in which porous or fpongy bo- 

 dies can be confolidated, and by which fubflances may 

 be formed into mafles of a natural fhape and regular ftruclure ; 

 the one of thefe is fimple congelation from a fluid ftate, by 

 means of cold ; the other is accretion ; and this includes a fepa- 

 ratory operation, as well as that by which the folid body is to 

 be produced. But, in whichever of thefe ways folidity is to be 

 procured, it muft be brought about by firft inducing fluidity, 

 either immediately by the action of heat, or mediately with 

 the afllftance of a folvent, that is, by the operation of folution. 



THUS, fire and water may be confidered as the general agents 

 in this operation which we would explore. We are, therefore, 

 to confider well, what may be the confequences of confolidation 

 by the one or other of thofe agents ; and what may be their fe- 

 veral powers with refpedl to this operation. 



IF we are not informed in this branch of fcience, we may 

 gaze without inftruc~lion upon the moft convincing proofs of 

 what we want to attain. If our knowledge is imperfect, we 

 may form erroneous principles, and deceive ourfelves in rea- 

 foning with regard to thofe works of nature, which are wifely 

 calculated for our inftruction. 



THE ftrata, formed at the bottom of the fea, are to be con- 

 fidered as having been confolidated, either by aqueous folution 

 and cryftallization, or by the effect of heat and fufion. If it 

 is in the firft of thefe two ways that the folid ftrata of the 

 globe have attained to their prefent ftate, there will be a cer- 

 tain uniformity obfervable in the effects ; and there will be ge- 



F f neral 



