16 GEOLOGY OF THE LOTHfANS. 



state of things entirely different from the present, if a for- 

 mation, whose relative position in the crust of the globe 

 was in one country correctly ascertained, exhibited in 

 every other a strictly uniform sameness in its mineralogi- 

 cal and fossilogical characters. If contemporaneous for- 

 mations were identical in all their details, the determina- 

 tion of strata would be conducted in a manner far different 

 from what it is. Instead of traversing extensive districts, 

 examining the relations of an unknown rock to others whose 

 natures were apparent, and from superposition and other 

 characters ascertaining geological equivalents, the mere view 

 of a characteristic specimen would be sufficient ; and from 

 geology being one of the most intellectual of Sciences, one 

 which requires minute investigation, it would deserve hardly 

 to be considered as an Art. 



Authors, in describing that series of rocks which lies, in the 

 regular succession, below the magnesian limestone, and above 

 the transition formations, divide it into the Old Red Sand- 

 stone, Mountain Limestone, and Coal Formation, drawing 

 lines of demarcation between all these deposits. Though, 

 from observing, in some countries, that the position of one 

 or all of these deposits is so unconformable, that it is only 

 to be accounted for by the state of repose which existed 

 during their several depositions, having been interrupted 

 by disturbing causes, still there is no reason to conclude 

 that this unconformability is to be observed in all countries. 

 This is to assume, that igneous actions in the early ages of 

 the world, differed entirely from those which now operate, 

 and also that the upraisures of contemporaneous strata were 

 themselves contemporaneous. A deposit which is completely 

 separated from that which succeeds it in one country, may 

 in another make a transition into it by numerous alterna- 

 tions; and thus we have a proof that breaks in the sequence 



