52 SKETCHES OF CREATION. 



as we now witness in some of the granites, which are mix 

 tures of quartz, feldspar, and mica ; or the syenites, which 

 are mixtures of quartz, feldspar, and hornblende ; or the 

 diorites, which are mostly mixtures of feldspar and .horn 

 blende. Or, perchance, the solidification took place under 

 such circumstances that the crystallization was more ob 

 scure, as in the various dolerites, which every one admits 

 to have been born of fire. We say that the process of re 

 frigeration must have resulted in such rocks as these ; and 

 it is a curious and instructive fact, that when we turn our 

 attention to an examination of the oldest rocks, we find 

 granites, and syenites, and diorites, and dolerites resting 

 where we expected them, underneath the rocks that came 

 into being after water existed upon the earth, spreading 

 out their bases in every direction, and constituting the 

 very abutment which supports the lithological pile. We 

 thus trace a certain succession of events which must occur 

 in accordance with the established laws of physics, and find 

 the series of sequents confirmed by the facts of the rocks 

 themselves. Though this mode of reasoning is not in the 

 spirit of modern natural science, it must always lead us to 

 the truth if we reason correctly. Nevertheless, it is sel 

 dom the case that we are justified in the attempt to predi 

 cate the phenomena from the laws which involve them, as 

 long as it is our privilege to confirm the laws by a study 

 of the phenomena. In the present instance, the history of 

 science shows that the laws were first arrived at by a care 

 ful induction from facts ; and the little deductive reasoning 

 in which we have indulged is but tracing the thread a lit 

 tle farther back, with the phenomenon it hangs upon all 

 the time in full view. 



In the process of refrigeration the stiffening crust would 

 become too large for the nucleus within. This would nec 

 essarily result from the more rapid contraction of the more 



