88 THE MICROSCOPE. June, 



their value and liow important a knowledge of the Bacil- 

 lariacesB is when studied this way. 



I have gathered the clay in various parts of North 

 Eastern New Jersey during the last four years. I had 

 it collected and collected it myself in New Hampshire 

 in 1873 and I had it from other spots in this country 

 and abroad and I looked for a geological reason for the 

 appearance of these so-called fresh-water, subpeat, or 

 lacustrine sedimentary deposits known as Diatomaceous. 

 I knew that they contained more or less of clay but I 

 did not find out how they came geologicaly until now. 

 I found them always to be associated with glacier ice. 



This ice age is a rather recent phenomena but how 

 long it lasted is not known. SuflBce it to say that in the 

 Eastern United States there was but one glacier ex- 

 tending from the pole to the 40th degree of parallel. 



I have gathered clay from a point eight miles above 

 Paterson city to New Brunswick and from the Hudson 

 river to above Morristown and I found it always the 

 same, resting beneath a thin covering about six inches 

 to a foot thick of alluvial and about three feet to over 

 ten feet thick upon the gravel, the red sandstone mor- 

 aine of the geologist. This moraine is very thick, over 

 thirty feet in some places. I have gathered the clay in 

 hundreds of places and always found it to contain Ba- 

 cillariaceaB, the same essentially in all cases. 



I gather from this that the clay was formed from the 

 granite and other rocks in the North and North West. 

 The clay is common in large quantities thicker at some 

 places where it settled to form kettle holes which were 

 first known as fossil Diatomaceous deposits. They are 

 common in New Jersey, New York, Connecticut, Rhode 

 Island, New Hampshire and New Brunswick and such 

 deposits as Wecquahick Lake in New Jersey, and Bow- 

 kerville in New Hampshire are called kettle holes. 



