NEW TERM FOR THE UPPER CAMBRIAN SERIES. 



During a recent revision of the classification of Cambrian 

 formations, in connection with the nomenclature and classifica- 

 tion to be used in the geologic atlas of the United States, it 

 became apparent that the term "Potsdam" or " Potsdamic " 

 could no longer be retained as the series nanie to include the 

 various formations referred to the Upper Cambrian. It was 

 used in this sense by me in 1891,'' but this usage has led to con- 

 fusion, owing to the term "Potsdam" being retained for the 

 well-known Upper Cambrian sandstone about the Adirondack 

 mountains. In order to avoid further confusion, the term Sara- 

 togian is now proposed to include the various formations com- 

 posing the Upper Cambrian series, leaving the term " Potsdam " 

 restricted to its original application, the Potsdam sandstone. 

 We shall then have the terms " Georgian" (Lower Cambrian), 

 "Acadian" (Middle Cambrian), and " Saratogian " (Upper 

 Cambrian) for the three series of formations of the Cambrian 

 system. 



The type locality of the Saratogian is north and west of Sara- 

 toga Springs, N. Y. The section has, at the base, about 200 

 feet of evenly bedded, compact, grayish to yellowish colored 

 sandstone, that rests unconformably against or upon spurs or 

 ridges of pre-Cambrian gneiss. At a locality three miles north 

 of Saratoga Springs the sandstone is about 40 feet in thickness; it 

 is overlain by an oolitic limestone, 30 feet, and a dark gray, 

 evenly bedded limestone 50 feet in thickness. In this latter 

 limestone the following fauna occurs : 



Crypto 20a proliferian. Billingsia saratogensis. 



Obolus {Lingiilepis) acioninatns. Matthevia variabilis. 



Platyceras 7uinnlissiinum. Dikelocephalus ha7-tti. 



Platyceras hoyti. Dikelocephahis speciosus. 



Metopto7na cornutiforine . Ptychoparia calcifera. 



Metoptoma simplex. (A.) saralogensis. 



^ Bull. U. S. Geol. Stirv., No. 81, p. 360. 



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