202 WALKS AND TALKS. 



. AN EARLIER 



INTIMATIONS OF A FIERY JEON. 



WE are searching for a beginning. We have followed 

 down the succession of formations to what seems a foundation ; 

 but we perceive this must rest on something which already 

 existed; it can not be the beginning. It is an ocean-born 

 mass of sediments. The ocean preceded the sediments. Some- 

 thing for the ocean to rest on preceded the ocean ; what was 

 that ? Not something born of ocean. What existed before 

 ocean and ocean sediments ? 



You have just seen (Talk XXXIV) that the deepest rocks 

 are hard and crystalline. We have concluded that their con- 

 dition has probably resulted largely from the action of water 

 and heat. Water alone would not dissolve the substances of 

 which these crystals are composed ; but heated water would be 

 much more efficient. Moreover, the addition of alkali to the 

 heated water would enable it to dissolve nearly all the sub- 

 stances in these lower rocks. However mud-like or sandy the 

 sediments originally were, heated alkaline waters would dis- 

 solve them; and then, if the solution were allowed to cool, the 

 various constituents would enter into such combinations as 

 suited their several affinities for each other. So the resulting 

 state of the materials would be extremely different from that 

 of the original sediments. This is at least a part of the pro- 

 cess called metamorphism of the rocks a subject to which 

 your attention has been many times called, and a cause of the 

 disappearance of any organic remains in rocks thus meta- 

 morphosed. 



But in this connection, the important point is the evi- 

 dence of ancient heat universally extended. I do not suppose 

 the metamorphism of the rocks has taken place at the surface. 

 The heat engaged seems to have been interior heat. It was 

 shut in and retained for ages by overlying masses of strata. 

 And yet I doubt if all metamorphic regions now exposed have 

 been formerly covered. Much yet remains to be learned about 

 metamorphism. 



