432 CONSISTENCY OF GEOLOGY WITH BACHED HISTORY. 



ted as we now see them. Crystallization by natural laws is constant- 

 ly going on around us and we can at pleasure, form crystals of many 

 substances ; in some cases, we produce those that never have been dis- 

 covered in nature, and in others we can surpass them in size and beau- 

 ty. Although, as already remarked, it is possible that crystals might 

 have been the first forms of mineral matter, it is in the highest de- 

 gree improbable ; it is far more reasonable and philosophical to admit 

 that wherever we find a crystal in the earth, it has been formed by the 

 laws of crystallization operating upon the crude materials and there 

 is no reason to doubt that we could always imitate natural crystals, 

 provided we could command the powers and circumstances which ope- 

 rated in the original crystallization of mineral bodies. In all the 

 geological epochs, after the primitive, there is decisive evidence of 

 great mechanical changes,* operating first on the primitive rocks, to 

 produce the materials for the derivative rocks, which often exhibit 

 unquestionable proofs of mechanical destruction and mechanical form- 

 ation ; in a word, of changes from the pristine state of the materials 

 in the primitive rocks, greater than crystallization implies in relation 

 to the constituent or integrant particles, \yhich we may presume to 

 have been originally created. 



As to the proximate causes of crystallization among minerals it 

 can be referred only to two agents, heat and solution. The only pow- 

 ers with which we are acquainted, that are at all equal to the effect, 

 are water, and fire, aided by various acid, alkaline, saline, and other 

 energetic chemical agents, which, in large quantities, we now find 

 actually entering into the constitution of the rocks, and which were 

 therefore originally provided in the grand store-house of created ma- 

 terials. 



The solution theory, once almost universally prevalent, has now 

 given way to the igneous, which not stopping with actual or extinct 

 volcanos or with trap, porphyry or pitchstone, has taken possess- 

 ion of the granite mountains and of the very centre of the earth. 

 It undoubtedly explains with great felicity, the appearances of gran- 

 ite veins and of many other phenomena, although neither the igneous 

 nor any other theory has explained every feature of the planet. 



It is allowed by nearly all geologists, that the ocean has for a long 

 time occupied all countries. It is now evident also, that ignition 

 and fusion have always existed in the earth on a great scale, and this 



* Among the primitive rocks, mechanical force is exhibited in fractures, eleva- 

 tions, &c. 



