OF CENTRAL CANADA PART III. 203 



amongst them, producing (in general) chemical or mechanical altera- 

 tions of greater or less extent. This action is still going on, as seen 

 in volcanic phenomena. 



(5) It is very generally assumed that the component matters of 

 the earth and other cosmical bodies existed originally in a diffused 

 nebulous condition, and gradually became condensed or solidified 

 after passing through a state of igneous fluidity. And it is assumed, 

 further, that this early molten condition of the earth is still retained 

 in subterranean depths. This view proposed by IMMANUEL KANT 

 and maintained by LAPLACE is necessarily hypothetical, but it is 

 supported by many collateral facts, and has been very generally 

 admitted.* If it be in the main correct, the rock-matters resulting 

 from the first consolidation of the earth's surface must have been 

 more or less akin to lavas and other volcanic products, although 

 probably of a somewhat denser character from the greater density of 

 the atmosphere then existing. No traces of these early lava-like 

 rocks are now, however-, visible. They must have been converted, 

 long since, into other products, or have been re-melted and re-con- 

 solidated, probably time after time, beneath increasing thicknesses of 

 superincumbent deposits. Sooner or later, after the first process of 

 consolidation had set in, the continued radiation of terrestrial h at 

 would allow the condensation of water to take place on the cooling 

 surface of the earth. Then, a new set of phenomena would arise. 

 The more exposed rock-surfaces would be worn down by aqueous and 

 atmospheric agencies, and the materials thus obtained would form 

 over the sea-bed a gradually increasing thickness of stratified deposits 

 most of which would undoubtedly be converted by subterranean 

 agencies into crystalline or metamorphic formations. The earliest 

 known rocks those which underlie all other strata are of this 

 metamorphic character. They form vast beds of gneiss, mica-slate, 

 hornblende-rock, chlorite-slate, quartzite, and other crystalline rocks, 

 inters t ratified here and there with beds of crystalline limestone and 

 dolomite, and are largely represented in Ontario and Quebec (see 

 Part V.) In some of their strata, within the last few years, some 



* "There are the strongest grounds for believing that during a certain period of its history 

 the earth was not, nor was it fit to be, the theatre of life. Whether this was ever a nebulous 

 period, or merely a molten period, does not much matter : and if we refer to the nebulous 

 condition it is because the probabilities are really on its side." PROFESSOR TYNDALL : Address 

 before the British Association : Liverpool, 1870. 



