THE EARLIEST STRATA MELTED VF. 353 



I/en, contained incompletely-fused clots of sedimentary 

 strata. Nor is this all. Fifty years ago, it was thought 

 that all granitic rocks were primitive, or existed before 

 any sedimentary strata ; but it is now " no easy task to 

 point out a single mass of granite demonstrably more an- 

 cient than all the known fossiliferous deposits." 



In brief, accumulated evidence clearly shows, that by 

 contact with, or j^roximity to, the molten matter of the 

 Earth's nucleus, all beds of sediment are hable to be 

 actually melted, or partially fused, or so heated as to 

 agglutinate their particles ; and that according to the tem- 

 perature they have been raised to, and the circumstances 

 under which they cool, they assume the forms of granite, 

 porphyry, trap, gneiss, or rock otherwise altered. Further, 

 it is manifest that thous^h strata of various as^es have been 

 thus changed, yet that the most ancient strata have been 

 so changed to the greatest extent : both because they 

 have habitually lain nearer to the centre of igneous agency; 

 and because they have been for a longer period liable to 

 the effects of this agency. Whence it follows, that sedi- 

 mentary strata passing a certain antiquity, are unlikely to 

 be found in an unmetamorphosed state ; and that strata 

 much earlier than those are certain to have been melted 

 up. Thus if, throughout a past of indefinite duration, 

 there had been at work those aqueous and igneous agen- 

 cies which we see still at w^ork, the state of the Earth's 

 crust might be just what w^e find it. We have no evidence 

 w^hich puts a limit to the period throughout w^hicb this for- 

 mation and destruction of strata has been going on. For 

 aught the facts prove, it may have been going on for ten 

 times the period measured by our whole series of sedimen- 

 tary deposits. 



Besides having, in the present appearances of the 

 Earth's crust, no data for fixing a commencement to theso 

 processes — besides finding that the evidence permits us to 



