The seven large Finger Lakes in central New York state
were formed when the last Pleistocene
ice cap melted back and flooded valleys previously overdeepened
by scouring of the advancing glacial ice. A thick veneer of glacial
debris, not shown here, overlies the lower Paleozoic bedrock indicated
on the map. The native American Iroquois believed that the fan-shaped
array of lakes are marks from the hand of the Great Spirit.