Transition Rocks of North America. 393 



the base of the Palaeozoic strata and the base of the first lime- 

 stone, the calciferous sandstone of New York. Of these, the 

 primal white sandstone would seem to be the only formation 

 existing in New York, or, according to Owen, on the north- 

 western margin of the basin in the western states. 



The Matinal series includes all the strata from the horizon 

 of the base of the calciferous sandstone, to that which marks 

 the top of the Hudson River slate in New York, and the top 

 of the blue limestone of the western states. This series, in 

 south-western Virginia, and East Tennessee, embraces a thick 

 and important middle group, consisting of three formations, 

 not extending north east of the New River, and only imper- 

 fectly represented in some portions of the western states. 



The Levant series includes all the formations between the 

 horizon, terminating the Matinal rocks, and one running 

 through the top of the water lime formation of New York, the 

 top of the non-fossiliferous and " pitted rock" of Lake Huron, 

 and through a plain low in the cliff limestone of the western 

 states. It takes in, therefore, the Medina, Clinton, Niagara, and 

 Onondaga salt groups, and water lime of the New York survey. 



The Premedidlal series embraces the strata between the top 

 of the water lime and the top of the Oriskany sandstone of New 

 York, and includes, therefore, the Pentamerus and Catskill 

 Shaly limestones of that state, as its oldest formation, and the 

 Oriskany sandstone as its newest ; and, besides these, a middle 

 formation not there seen, but well developed in Pennsylvania, 

 with characteristic fossils. 



The Medidial series ranks in it all the strata between the 

 top of the Oriskany or Premedidial sandstone and the 3far- 

 cellus black slate of New York, or the black bituminous slate 

 of Ohio, Indiana, Kentucky, and Middle Tennessee. It, there- 

 fore, includes the Schoharie grit and Onondaga and corfiifer- 

 ous limestones of New York, and the upper division of the cliff 

 limestone of the wesit. 



The Postmedidial series embraces that very natural assem- 

 blage of formations, commencing with the black slate just 

 named, and crossing with the horizon which marks the base 

 of the Catskill red sandstone. It contains, therefore, for New 

 York, the Marcellus shades, the Hamilton group, the Tully 



