44 LAMINATED CLAYS OF GRANTSBURG, WIS. 



Its age is late Wisconsin stage of the glacial period, and is in a 

 minor way interglacial. 



The character of lamination is considered to indicate a seasonal 

 accumulation. Each unit of lamination, therefore, measures a year. 



The total thickness of the deposit divided by the average thickness 

 of the unit of lamination gives a number equivalent to the length of 

 time occupied in its accumulation. This is approximately 1,700 

 years. 



If correct at all, the above furnishes a more precise measure for a 

 part of the postglacial interval than is obtained from any other source. 

 The part of this interval involved is but one of the minor fluctuations 

 of the retreating ice in the vicinity of Grantsburg, Wisconsin. 



Evidence from this source is opposed to the lowest estimates of 

 postglacial time as computed from Niagara and St. Anthony Falls. 



