1867.] the Western Himalaya and Afghan Mountains. 87 



great beds of rock in these mountains, is towards the N. E. ; an explana- 

 tion of the cause of this dip will be given hereafter. 



86. We have said that granite may be considered as the consoli- 

 dated materials of " blind volcanoes ;" that is, the cooled down masses 

 of fluid or viscid matter propelled by internal tension towards the 

 surface of the globe, but not with a force sufficient to overcome the 

 resistance offered by the earth's crust. The soundness of this hypothesis 

 appears supported by the metamorphic influence of granite over im- 

 mense tracts of country : the conversion of shales, limestone, and sand- 

 stones and other rocks into gneiss, schist, marble and quartzite can only 

 be explained either by supposing these shales, limestones, and sandstones 

 to have been plunged deep into the bowels of the earth, there to be me- 

 tamorphosed, — or else to have been the lid, covering and keeping under 

 waves of fluid mineral matter. Now, the first supposition necessitates 

 the assumption of very great disturbances of the earth's crust, of such 

 disturbances as we cannot conceive or imagine by the analogy of any- 

 thing we now see in the rocks of the surface of the globe. Neither is 

 the idea of superficial stratified beds being plunged to a great depth 

 into the earth, agreeable to the universal observation of a forcing-out 

 power acting from the centre to the surface. The other supposition 

 does not present the above-named objections : immense masses of 

 melted matter may have approached sufficiently near the surface to 

 have imparted great and continued heat to the deepest stratified beds, 

 and may have underlaid great tracts of country, without disturbing, to 

 a very great extent, the position of the strata which they metamor- 

 phosed. Hence do we find beds of gneiss, schist and marble retaining 

 great regularity of stratification for very many miles ; so much so, 

 that it has been possible to classify these metamorphic rocks in regularly 

 superposed formations, and to ascertain non-conformity between these 

 beds, proving beyond a doubt their successive deposition.* It is 

 impossible to understand how these beds could have preserved their 

 relations, over a great extent of country, if it had been submitted, at one 

 time, to a " oouleversement" so terrific and complete as to have plunged 

 them under the solid crust of the earth, and, at another time, to the 

 great upheaval necessary to bring them up again to the surface. 



* The great example of this is Sir W. Logan's Laurentian formations in 

 Canada. 



