42 RELATION OF UNSTRATIFIED 



originally existed, was owing to the solvent power of heat ; 

 a power whose effect in melting the most solid materials of the 

 earth we witness in the fusion of the hardest metals, and of 

 the flinty materials of glass.* 



Beneath the whole series of stratified rocks that appear 

 on the surface of the globe (see section PI. 1,) there proba- 

 bly exists a foundation of unstratified rocks ; bearing an ir- 

 regular surface, from the detritus of which the materials of 

 stratified rocks have in great measure been derived,f amount- 

 ing, as we have stated, to a thickness of many miles. This 

 is indeed but a small depth, in comparison with the diame- 

 ter of the globe ; but small as it is, it affords certain evidence 

 of a long series of changes and revolutions ; affecting not 

 only the mineral condition of the nascent surface of the earth, 

 but attended also by important alterations in animal and ve- 

 getable life. 



The detritus of the first dry lands, being drifted into the 

 sea, and there spread out into extensive beds of mud and 



* The experiments of Mr. Gregory Walt on bodies cooled slowly after 

 fusion ; and of Sir James Hall, on reprodueinn- artificial crystalline rocks, 

 from the pounded ingredients of the same rocks highly heated under 

 strong pressure : and the more recent experiments of Professors Mitscher- 

 lich and Bcrthier, on the production of artificial crystals, by fusion of definite 

 proportions of their component elements, have removed many of the objections, 

 which were once urged against the igneous origin of crystalline rocks. 



Professor Kersten has found distinctly formed crystals of prismatic Fel- 

 spar on the walls of a furnace in which Copper slate and Copper Ores had 

 been melted. Among these jnjrochemically formed crystals, some were sim- 

 ple, others twin. They are composed of Silica, Alumina, and Potash. This 

 discovery is very important, in a geological point of view, from its bearing on the 

 theory of the igneous origin of crystalline rocks, in which Felspar is usually 

 so large an ingredient. Hitherto every attempt to make felspar crystals by 

 artificial means has failed. See Poggendorf's Annalen, No. 22, 1834, and 

 Jameson's Edin. New. Phil. Journal. 



t Either directly, by the accumulation of the ingredients of disintegrated 

 granitic rocks, or indirectly, by the repeated destruction of different classes 

 of stratified rocks, the materials of which had, by prior operations, been de- 

 rived from unstratified formations. 



