THROUGH THE GEOLOGIST'S EYES 



at one time in the original granite, or in the primor- 

 dial seas, or in the primordial atmosphere, or in 

 the heavens above, or in the interior of the earth 

 beneath. We must sweep the heavens, strain the 

 seas, and leach the air, to obtain all this material. 

 Evidently the growth of these rocks has been mainly 

 a chemical process — a chemical organization of 

 preexisting material, as much so as the growth of 

 a plant or a tree or an animal. The color and tex- 

 ture and volume of each formation differ so radically 

 from those of the one immediately before it as 

 to suggest something more than a mere mechanical 

 derivation of one from the other. New factors, 

 new sources, are implied. "The farther we recede 

 from the present time," says Lyell, "and the higher 

 the antiquity of the formations which we exam- 

 ine, the greater are the changes which the sedi- 

 mentary deposits have undergone." Above all have 

 chemical processes produced changes. This con- 

 stant passage of the mineral elements of the rocks 

 through the cycle of erosion, sedimentation, and re- 

 induration has exposed them to the action of the 

 air, the light, the sea, and has thus undoubtedly 

 brought about a steady growth in their volume and 

 a constant change in their color and texture. Marl 

 and clay and green sand and salt and gypsum and 

 shale, all have their genesis, all came down to us in 

 some way or in some degree, from the aboriginal 

 crystalline rocks; but what transformations and 



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