410 



HISTORICAL GEOLOGY. 



352. 



Permian. 



Upper Coal-measuree. 



.Vvyvvvvvvvvv 



vvvvvvvvvvvv 



Lower Coal-measurea. 



Millstone Grit. 



Upper, or Mauch Chunk. 



Lower, or Pocono. 



Chemung and Catskill. 

 Portage, Genesee. 



Hamilton. 



Marcellus. 



Corniferous. 



Schoharie and 

 Cauda-galli. 

 Oriskany. 



Lower Helderherg. 



Salina and Water Lime. 



Niagara. 



Clinton. 



Medina. 



Hudson. 

 Utica. 



Trenton. 



Chazy. 



Calciferous. 

 Potsdam. 



Acadian. 



Georgian. 



Archssan. 



