8 



NEW YORK STATE MUSEUM 



daries are rendered very conspicuous by their strong escarpment. Over 

 this lies the Pentarnerus (Coeymans 1 ) limestone, characteristically devel- 

 oped, and thereon a well defined mass of Catskill shaly (New Scot- 

 land 1 ) limestone. The latter is overlaid by the Becraft 1 limestone. To 

 these four formations Davis assigned the following thicknesses: 



Manlius limestone 20-30 feet 



Coeymans limestone 40-50 feet 



New Scotland beds 50-60 feet 



Becraft limestone 40-50 feet 



'The requirements of uniformity in stratigraphic nomenclature are compelling 

 the relincpiishment of such of the early division names in the New York series as 

 do not indicate localities of exposure. In order to save to the state of New York 

 its preeminent title to the names of these divisions and in the farther hope of per- 

 petuating an equable grouping of the stratigraphic units of the New York series, the 

 writer, in conjunction with Charles Schuchert, has recently (Science. Dec. 8, 1899, 

 American geologist. Feb. 1900) proposed the arrangement of the formations given 

 in the following table. This proposition has been carefully considered and is the 

 result of mature deliberation. 



NEW YORK SERIES 



ERA OR SYSTEM 



PERIOD OR GROUP 



AGE OR STAGE 



Cambric 



or 

 Taconie 



Champlainic 1 



(Lower Silurian and 

 Ordovician) 



Georgian 



Acadian 



Potsdamian 



Canadian 3 

 (Paleochamplainic) 



Mohawkian 4 

 (Mesochamplainic) 



Cincinnatian 5 

 (Neochainplainic) 



Georgia slates 



Potsdam sandstone and limestone 



[ Beekmantown limestone 16 

 I Chazy limestone 



f Lowville limestone 16 

 \ Black river limestone 

 [ Trenton limestone 



Utica shale 



Lorraine beds 17 



Kichmond beds (Ohio and Indiana) 



