Wanting in the States north of the Ohio River. 



AMERICAN GEOLOGY— DECADE OF 1840-1S49. 421 



CLIFF LIMESTONB. 



5. Trenton limestone. 



Galena limestone. ^Wanting at the east and southeast. 



6-8. Hudson River group. I 



9. Oneida conglomerate. \ ... . 



°, ^Wanting at the west. 



10. Medina sandstone. I 



U. Clinton croup. X—, x ,. , .. , ,. , ., .,,. . 



(The Niagara and the calcareous portion oi the ( hnlon. 

 L2. Niagara group. ' 



13. Onondaga salt group. Wanting west of Lake Michigan. 



14. Tentaculite limestone. 



15. Pentamerus limestone. 



16. Delthyris shaly limestone. 



17. Encrinal limestone. 



18. Upper Pentamerus limestone. 



19. Oriskany sandstone. \,_. , ,, ,, , 



•',,. . >\\ anting at the west and southwest. 



i'0. Cauda-galli grit. > 



21. Schoharie grit. 



22. Onondago limestone. 



23. Corniferous limestone. 



The following table was intended to show the equivalency of the 

 Now York forms with those of Europe 1 : 



, ., . f? Trenton limestone, in part. 

 Llandeilo fiags.i„ , T ,. , , 

 p 1 ? I tica slate. 



_, , „ (Hudson River group. 



Caradoc sandstone.) _,. , , 



IClinton group, m part. 



i Clinton group, in part. 

 Niagara group. 

 Lower Helderberg limestones. 



Upper Helderberg limestones. 

 Ludlow series and Devonian system.. Hamilton group. 



Chemung group. 

 Red sandstone and shale of Catskill Mountains. 



The Chazy, Bird's-eye, and Black River limestones, the Onondaga 

 salt group and the Oriskany sandstone he regarded as having no 

 representation among British strata. 



Commenting on the proportion of species represented by European 

 authorities as passing from Devonian to Carboniferous, he wrote: 



It is so enormously great that we find no parallel to it in any preceding period. 

 * * * From all these farts there seems to he but one conclusion, and that is, in 

 the British Isles particularly, either there are remarkable exceptions to the general 

 law in the continuation of species from one to another or that there is no foundation 

 for a distinction between the Devonian and.Carboniferous systems. 



Further on he wrote: 



We can not avoid the conclusion that, if we adopt the Devonian system with the 

 limits suggested by foreign writers, we must drop forever the attempt to recognize 

 the Ludlow division of the Silurian system. 



