AN 



OUTLINE OF GEOLOGY, 



SHOWING 



ITS CONNEXION WITH THE LAWS 

 OF 



TERRESTRIAL MAGNETISM 



INTRODUCTION. 



ALTHOUGH geology has been brought, and now established 

 as a distinct science, it must be admitted that the theories pro- 

 mulgated to account for the observed phenomena are in a most 

 crude state —contrary to analogy, and not only unsupported by, 

 but in direct opposition to, the evidence afforded by the pheno- 

 mena themselves. We search in vain for any useful fundamen- 

 tal rules to guide us in subterraneous operations, even in a trea- 

 tise professedly called practical, much less in those of a more 

 theoretical character. Indeed the science may be considered at 

 present as c Fossil Geology ' combined with Comparative Ana- 

 tomy, — principally confined to the examination of the relics of 

 the past entombed in the sedimentary rocks, which branch, 

 being somewhat more enchanting, has monopolized nearly the 

 whole attention and interest of this more generally useful science. 

 If we refer to the descriptions of the Primary rocks, we find them 

 so imperfect and so inapplicable to their general structure, and 

 mixed so much with hypothetical ideas, that those who derive 

 all their knowledge from books must imagine these rocks as con- 

 fused igneous masses void of all order. Those who are practi- 

 cally acquainted with the subject have a very different opinion, 

 and know that the crystalline rocks possess an harmonious sym- 

 metrical structure. 



It is a very common remark in geological books, that great 

 mistakes are committed in mining and other subterraneous works 



B 



