THE DELAWARE LIMESTONE 421 



(Lorraine beds) and the base of the Marcellus shale. Later studies, 

 however, have shown that the "Pyritous slates," forming the basal 

 member of his Helderberg division, are probably of Salina age; 1 

 while Mather's succeeding division — the Water limestone — which 

 he gave as composed of two members, the Water limestone and 

 Tentaculite limestone, now called the Rondout waterlime and the 

 Manlius limestone, is also separated from the Helderbergian series as 

 defined by Dr. John M. Clarke, and put in the subjacent Cayugan 

 series. 2 



Professor Hall in 1859 divided the rocks of the Helderberg moun- 

 tains into the Lower and Upper Helderberg groups, which were 

 separated by the Oriskany sandstone and Cauda-galli grit. 3 The 

 Upper Helderberg group was composed of the Schoharie grit and 

 Onondaga and Cornif erous limestones ; or, in other words, it included 

 the rocks between the top of the Cauda-galli grit (now called Esopus 

 grit) and the base of the Marcellus shale. 



Regarding Whitfield's discovery Dr. Orton said: 



At a few points in central Ohio the upper division [Delaware limestone] has 

 been found in a shaly state and carrying characteristic fossils of the Marcellus 

 slate. This fact was first noticed in its true significance by Whitfield. 4 



The name "Upper Helderberg limestone" was used by Dr. Orton 

 for the formation, and the same reasons for its use were published 

 in his first annual and final report of the Geological Survey of Ohio; 5 

 but in his last review of the " Geological Column of Ohio" he returned 

 to the earlier name of "Corniferous limestone." 6 



In the last edition of Dana's Manual the Delaware limestone is 

 apparently considered as of Hamilton age, for in giving the distri- 

 bution of its beds it is stated that "they appear also in Ohio, as 



1 Hartnagel, New York State Museum, Bulletin No. 6g (" Report of the State 

 Paleontologist," 1902), 1903, pp. 1116, 11 70, 1171. 



2 New York State Museum, Handbook No. ig (1903), pp. 8, 9, 14. 



3 Paleontology of New York, Vol. Ill, Part I (1859), p. 97. 



4 Report of the Geological Survey of Ohio, Vol. VI (1888), p. 22. 



s First Annual Report of the Geological Survey of Ohio (1890), pp. 24-26; Report 

 of the Geological Survey of Ohio, Vol. VII (1893 [1895]), pp. 18, 19. 



6 Nineteenth. Annual Report of the United States Geological Survey, Part IV (1899), 

 pp. 638, 646, 682. 



