124 THE AMERICAN MONTHLY [April 



On a Fossil Lake in Xew jersey. 



By ARTHUR M. EDWARDS. M. D.. 



NEWARK, N. J. 



[Read before the Washington Mitrosropiciil .Society.! 



1 wi.sli to record here the finding;- of a fossil lakr in 

 New Jersey; first, betuiise it give.s iiic an opportunity of 

 clearing up t he knowledge of infusorial caiths and also 

 because I found in it two .strata of fossil bacillaria, com- 

 monly called diatomacea', one below fresh-water and one 

 above brackish water forms. Beside the.se are growing 

 uow and de})Ositing their shells, fresh-water bacillaria. 

 This was the first that I can find containing the fresh 

 and brackish water layers of bacillaria, and shotild be re- 

 corded for that reason alone. But 1 was. therefore, led 

 to study closely the genesis of similar infusorial earths and 

 1 have come to the conclusion that they all, in this coun- 

 try as well as in Europe, are the same litholo;;ical]y and 

 the same in the foiins of bacillaria seen in them. 



The earth is clay and so are all of them in North and 

 South America and in Euro])e. When discovered, it was 

 communicated to the San b'l'ancisco Microscopical Society 

 on the 21st of .January, IStU. 1 than called it an inti'a- 

 glacial deposit, it being su[)|iosed that it lay betwrtMi the 

 two glacial moraines which 1 supposed were here in Xcw 

 Jersey. Hut then I studied the glacial moraine and I 

 found there was but one in this jiart of the state. I also 

 learned tliat glacialists were inclined to jtlace but one in 

 the east, although they were doublfnl if there were two 

 in the west. I now call it ieeber,<; pei'iod clay, l)eing 

 formed when t he ice of f he izlacial jieriod was meltinp," 

 and broke into icebergs on the margin. This margin 

 moved further north as the ice melteil aiel at l.ast disap- 

 peareil. When 1 found the earth, it was just de\elop(Ml. 

 being turned up by the Lehigh N'alley railroad forming 

 a bank across a marsh whieh 1 learned had been a lakt.' 

 formerly. 



