52 NEW YORK STATE MUSEUM 



during the closing stages of the Ice Age and just afterward, north- 

 ern New York, including the area of the Luzerne quadrangle, lay- 

 hundreds of feet below its present altitude, and that tide water 

 extended through the Champlain valley. 



This is proved by the presence of marine beaches with fossils 

 several hundred feet above sea level in the Champlain valley. The 

 most recent earth movement in northern New York has brought 

 the marine deposits to their present altitude. This earth movement 

 has been differential with greatest uplift toward the north, the rate 

 of increase northward having been several feet per mile. The 

 differential uplift appears to be clearly recorded within the Luzerne, 

 North Creek, and Schroon Lake quadrangles where delta terraces 

 and sand flats of former glacial lakes gradually increase in altitude 

 northward at the rate of several feet a mile. 



Lakes and Their Deposits 



Glacial Lake Warrensburg. During the final retreat of the 

 great glacier from northern New York, according to Fairchild,^*' 

 the drainage of the Mohawk valley was, for a long time, blocked 

 by the waning Ontarian ice lobe on the west and the waning Hud- 

 sonian ice lobe on the east. Glacial lake waters occupied the ice- 

 freed portion of the Mohawk valley. Beginning with a lake whose 

 outlet was southward into the Susquehanna, the glacial waters first 

 increased and then diminished in size but fell to lower and lower 

 levels as the retreating Hudsonian ice lobe opened up lower and 

 lower outlets into the Hudson valley. Fairchild's maps^^ graphi- 

 cally illustrate the principal stages in this history M^hich bears 

 directly upon the interpretation of certain extensive, but now 

 extinct, postglacial bodies of standing water in the Luzerne 

 quadrangle. 



Even a brief examination of the Hudson and Sacandaga valleys 

 of the Luzerne quadrangle would make it clear that they were 

 occupied by standing waters after the glacier disappeared from the 

 district. That this was so is proved by the extensive development 

 of deposits which were laid down under water since the retreat of 

 the ice. Delta terraces and sand plains or flats formed by the 

 streams which emptied into the standing waters are common in 

 many parts of the valleys. 



'N. Y. State Mus. Bui. i6o, 1912. 

 N. Y. State Mus. Bui.. 160, 1912, plates 13 to 17. 



