88 NEW YORK STATE MUSEUM 
time of maximum glaciation, and also the three great centers of 
accumulation and dispersal of the ice. The directions of flow of 
the ice from these centers have been determined by the study of 
the directions of a very large-number of glacial striae or scratches. 
Fic. 29 Map of North America showing the maximum extent of the 
great ice sheets of the Quaternary period. The three great ice centers are 
shown by the letters as follows: L.— Laborador or Laurentide Glacier; 
K = Keewatin Glacier; and C=Cordilleran Glacier. All of New York 
State, except probably the very southern border of Long Isiand and the 
southern part of Cattaraugus county, was buried under the ice. 
It was the Labradorean or Laurentide ice sheet which spread south- 
ward over New York to cover all the State except the southern. 
border of Long Island. It must of course be remembered that the 
