Feathers tonhaugh\s Geological Report. 65 



composed of oxides, as we may suppose the greater portion of 

 the exterior to be. The contents may partially consist of pon 

 derous bodies, of the nature of metalloids, and great cavities 

 may exist there. The existence of volcanic action through 

 every part of the known world, either by the eruptions of 

 active volcanoes or by earthquakes, is an assurance that there 

 must be vast cavities in the interior where igneous action is 

 fiercely at work, and of which these volcanoes may be con 

 sidered as the safety-valves. The disturbances resulting from 

 earthquakes may be considered as the effect of the resistance 

 which the solid parts of the crust of the earth oppose to the ex 

 pansive power striving in those profound cavities. Applying this 

 power to many phenomena of the science, we are able to com 

 prehend what would otherwise be incomprehensible. The low 

 est rocks which have yet been met with in penetrating into the 

 crust have been of the granite kind ; but in ascending to the sum 

 mits of some of the highest mountains, we find them composed 

 also of granite. We have no method of explaining this apparent 

 paradox but in having recourse to this subterranean force, and 

 giving due attention to the multiplied evidences of its intense 

 exertion. Thus, when we observe some of the stratified beds 

 which lie much higher up in the series than the granite, re 

 posing at high inclinations upon the flanks of the granite 

 mountains, with accompanying marks of violent dislocation, 

 the truth flashes upon us, and we perceive that these mountains 

 have once existed at lower levels, and that they have been 

 forced up through the superincumbent beds. We thus become 

 acquainted with the existence of a power capable of the 

 mightiest mechanical exertions. If earthquakes in our time 

 rend the earth, dislocate its solid parts, and ingulf portions of 

 it in the chasms they produce, what were they not capable of 

 when the subterranean force, at an early period of the deposi 

 tion of strata, was infinitely more energetic, and had much less 

 resistance opposed to it ? 

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