THE POTSDAM SANDSTONE OF THE LAKE CHAMPLAIN 



BASIN 



NOTES ON KIELD WORK! 1901 



WITH MAP 



BY GILBERT VAN INGEN 



The Potsdam sandstone of northern New York is, in the 

 bibliographic sense, one of the best known members of the 

 geologic column. For many years it was considered the lowest 

 member of the series of sedimentary rocks, and was, as such, 

 supposed to contain the oldest known representatives of 

 organic life. In this relation the description of the formation 

 was given considerable prominence in textbooks and its name 

 became a familiar one to students of natural history. In view 

 of these facts it is a matter of surprise that there is at hand 

 so little definite information regarding the physical and biologic 

 characteristics of this formation, which is in reality the least 

 known element of the sedimentary series of New York. Since 

 the original description of the formation by Emmons in 1837-43 

 little has been added to our knowledge of it as developed within 

 the boundaries of this state. Logan^ described with consider- 

 able detail the group as developed in its northward extension 

 into Canada and added several items of interest to those noted 

 by Emmons. \Yalcott2 gives a few notes on the relations of 

 the Potsdam to the overlying formations in the vicinity of 

 Saratoga and Washington counties. Again in 1891 Walcott 

 briefly describes several sections through the formation along 

 the northern and eastern flanks of the Adirondack mountains, 

 in which are given the thickness of the deposits, general state- 

 ments on the character of the materials, and in which certain 

 fossiliferous zones are recognized as occurring at horizons in 

 the upper part of the series. Ells, 1894, in a paper on the 

 Potsdam and Beekmantown formations of Quebec and eastern 

 Ontario, describes the transition from the sandstone of the 



'Geology of Canada. 1863. p. 87-96. 

 - U. S. geol. survey. Bui. 30. 18SG. p. 21. 



