432 



PLEISTOCENE OF INDIANA AND MICHIGAN. 



In southern Ontario the following instrumental measurements of the highest Algonquin 

 beach have been made by Goldthwait and by W. A. Johnston (see PI. XXV) : 



Altitudes of highest Algonquin beach in southern Ontario. 



Goldthwait 1 gives a table of altitudes of the Algonquin beach in the area of horizontality. 

 Most of these are included in the tables above. The averages for those in the Lake Michigan 

 and Lake Huron basins taken separately show a difference of about a foot in the altitude of the 

 beach in the two basins. One or two abnormally low measurements are included for Lake 

 Michigan, and two abnormally high ones are included for Lake Huron. In a region in which 

 many measurements agree in showing horizontality, measurements abnormally high or low 

 should not be included in making averages. Perhaps it is not impossible that a slight hump or 

 hollow may occur in an area where the beach is prevailingly horizontal, but present knowledge 

 does not warrant such an assumption. No instance of such an occurrence has been proved. 

 Altitudes of 603 feet for the Algonquin in the Michigan basin are a little below normal, and the 

 altitudes of 610 by Cooper and 611 by Lane in the Lake Huron basin are abnormally high; 

 and in both of the latter localities the beaches are known to be sandy and quite likely to be above 

 normal height in consequence of wind action. If the abnormal measurements be omitted the 

 altitude of the beach in the two basins becomes nearly the same. 



The following measurements of the altitude of the Algonquin beach in Ontario were made by 

 Spencer more than 25 years ago and, except where otherwise stated, were made with a spirit 

 level. Some terraces which he gives in his table are omitted. The difference between these 

 values and those obtained by Goldthwait are probably mainly due to slight differences of locality, 

 for Spencer's descriptions of localities were seldom sufficiently detailed for exact identification. 



Altitudes of highest Algonquin beach in Ontario. 



Height 



above Lake 



Huron. 



Feet. 



Grand Bend of Au Sable River 



Southampton 



Owen Sound 



Clarksburg 



Collingwood, 4 miles west 



Colwell 



Elmsvale 



\V ve bridge, east of 



< )rillia (barometer) 



Kirkfield 



Bull. Geol. Soe. America, vol. 21, No. 2, 1910, pp. 236-23' 



