Ch. XVI.] TO THE PREVAILING THEORY. 379 



partial state of fusion. Whilst the primary slates next 

 granite not only exhibit similar appearances, but differ from 

 the more remote portions of these rocks in their chemical 

 composition, which, if indicative of any alteration, points to 

 the transmutation of one earth into another ; such as that of 

 alumina, or of lime, into silica. But this is not the only 

 difficulty ; for all the primary strata, excepting occasional pure 

 beds of limestone and quartz-rock, if there be such, contain 

 some alkali which does not exist in the sedimentary rocks : 

 and many arguments have been brought forward to prove 

 that the alkalies could not have been introduced by the granite ; 

 for if so, it must have traversed some beds, without entering 

 into combination therewith, though these occasionally consist of 

 quartz, which, according to theory, must have been in a state 

 of ignition. The principles of chemistry do not form the only 

 grounds of objection to the so-termed metamorphoses, for 

 these are also at variance with the laws of caloric : for how can 

 it be conceived that heat could be so transmitted through such 

 a vast extent of non-conducting beds of clay and sand, as to 

 produce its greatest effects at a considerable distance from its 

 source, without bringing the nearest beds into a state of 

 perfect fusion, or, indeed, without causing any, or but very 

 little alteration in several intermediate strata ? 



Such are the principal objections which, in the preceding 

 chapters, we have advanced against the prevailing theory, and 

 we venture to express a hope that they will be deemed 

 sufficiently important to obtain a candid and patient exa- 

 mination. 



For these various considerations, we therefore conceive that 

 the prevailing theory is not in accordance with the phenomena 

 of the primary rocks, and that it is not founded on a full and 

 fair deduction from facts. We are informed that the modern 

 or improved method of theorising " seeks an interpretation of 

 geological monuments by comparing the changes, of which 

 they give evidence, with the vicissitudes now in progress, or 



