VALLEY OF THE MISSISSIPPI. 35 



ctous iron ore, salt springs, aud nitre, with several 

 other materials of minor importance are almost con- 

 comitant with this formation, and tend to character- 

 ize and distinguish it when it assumes an almost ho- 

 rizontal stratification. It is greatly to the advantage 

 of the miner and the mineralogist, as well as to seve- 

 ral branches of public economy, that such geo- 

 logical distinctions could be drawn betwixt the dif- 

 ferent strata and formations of minerals, as might al- 

 ways prevent the waste of money and labour. Yet, 

 after all, it is to be regretted, that the ambiguity of 

 certain strata is sometimes so great, as to admit of 

 considerable argument in ascertaining their differ- 

 ence ; such, in a great measure, is the character of 

 the second calcareous formation which now claims 

 our attention. 



In its geographical limits, it occupies a position 

 universally to the east of the primitive and transition 

 formations. Its existence, as far as I know, has not 

 been ascertained to the north of the bay of Chesa- 

 peake; it here makes its appearance in the vicinity 

 of Annapolis, and presents several features common 

 to the transmontane stratum. It appears, however, 

 to be destitute of the concomitant minerals, except- 

 ing, indeed, it were possible to conceive it in con- 

 nexion with the coal basins of Richmond, which I 

 have found on examination to be actually underlaid 

 with a calcareous rock of a peculiar appearance. 

 Mr. Heath's coal-mines, and, in fact, nearly all of 

 them, except those which were in a state of combus- 



