280 IDENTITY OF THE WESTERN FORMATIONS 



New Albany, many of ihc fossils common to the rocks of New 

 York, and w liich fully confirmed my views relative to the posi- 

 tion of those examined. These fossils were principally from the 

 rock at the falls of the Ohio. From comparing my observations 

 of other rocks with those made by Dr. C, I became still further 

 convinced of the identity of different portions of the formations of 

 the West with those of New York * and that the limits of many 

 of the rocks were as well marked there as at the East. 



Above Jhe limestones last described we meet with a "black 

 bituminous shale," which, from position, seems to be the equiva- 

 lent of the»Mai-cellus shale of New York,t and is the only repre- 

 sentation of that rock, the Hamilton group and Genesee slate ; for 

 we pass directly from this to the green shales and slaty sandstones 

 of the Portage gi'oup or Waverley sandstone series of Ohio. In 

 the examinations made in these rocks for several hundred feet 

 upwards, no change from the Portage to Chemung gi'oups could 

 be identified, fossils for the most pai't being absent. I should not 

 omit to state, however, that in passing beyond these greenish 

 slaty rocks to a more micaceous and ferruginous yet friable sand- 

 stone, I found several shells which beai* close analogy, if not 

 absolute identity, with the Chemung species. But finding after- 

 wards, in other parts of this sandstone, shells evidently belonging 

 to carboniferous types, I was led to question the inference as to 

 absolute identity.^ Further investigations proved that this sand- 

 stone, in passing upwards, became interstratified with beds of 

 limestone, and thin courses of oolitic limestone with fossils 

 occured in several places. These latter were not persistent, but 

 in some places were found several inches thick and soon dis- 



* From a letter of Dr. Clapp to the Philadelphia Academy of Natural Sciences, dated 

 February, 1S42, I am happy to see that his views regarding the identity of the rocks of that 

 region with certain formations of New York essentially correspond with what I had ex- 

 pressed in the Am. Journal of Science of .January preceding. 



tNear New Albany this shale is one hundred and four feet thick, " in other situations 

 it is only fifty feet thick," — Second Ann. Rep. of Geological Survey of Imliatia, page 15. 



tThe fossils referred to as similar to those of Chemung, are a species of Dellhyris, a 

 Strophomena, an Atrypa and an Inoceramus. Their absolute identity has not been de- 

 termined from want of an opportunity to compare with specimens fiom the rocks of New 

 York. 



