Feather stonhaugh* s Geological Report. 19 



new ones from their ruins, at other times producing new strata 

 from mineral solutions. 



Accordingly one of the most interesting problems in geology 

 is to separate those periods from each other, and to ascertain, 

 by the mineral structure of such rocks, by the organic remains 

 imbedded in them, and by the measure of conformability of 

 strata to a horizontal line, the positive affinities and differ 

 ences between them all. By this process, an estimate may 

 eventually be formed of the exact amount of those affinities 

 and differences in the most distant parts of the earth, and a 

 consentaneous judgment be pronounced upon the nature of 

 those causes, from the universality or locality of their effects, 

 whether they are constitutional to the planet or not. 



It is then, only, that a nomenclature founded upon those un 

 erring principles by which nature is constituted, can be es 

 tablished and applied to all the strata and phenomena which 

 have preceded the present order of things, being those which 

 are peculiarly the objects of geological inquiry. It will prob 

 ably also be found that the judgment which will ultimately 

 be formed will be confirmed by what is passing in the present 

 order of nature, where the sum of affinities and differences is 

 still further extended, and where the partial production of 

 rocky matter, whether of a sedimentary or intrusive nature, 

 is obviously caused by the action of the same universal prin 

 ciples. 



In accordance with the intention to treat this subject in an 

 elementary manner, a brief account will be given of the princi 

 pal strata composing the geological column, as it has been ob 

 served in Europe, noticing, at the same time, the American 

 beds, which, from their general agreement and position in the 

 series, have been thought to be equivalents j premising, how 

 ever, that where a group of beds occurs, the members of which 

 have a strong affinity for each other in mineral structure and or 

 ganic remains, and which differ materially from the adjacent 

 beds lying above or below, it is sometimes called a formation, 



