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Map: New York State during the last Ice Age, depicting the Ontarian Lobe of the Labradorian Ice Sheet.
Map indicating preponderance of mammoth (not mastodon) remains in New York State, at the period of Lakes Iroquois and Albany. It was at this time of glacial recession, when the St. Lawrence Valley was still blocked by ice, that the great Iromohawk, carrying the waters of the Great Lakes basin through the channel of the Mohawk of today, cut down the Adirondack mountain barriers at present Little Falls and the Noses, moulded the lower levels of the Valley and made its channel bed where the fertile Mohawk flats now lie. The former annual spring freshets of the present Mohawk gradually laid a level bed of silt on this old Iromohawk channel, which makes the level flats of today. The Iromohawk River of this glacial period probably rivaled the present-day Niagara River. From New York State Museum Bulletin 241-242.