<P> The subsequent melting of the ice dam resulted in a sudden lowering of the lake to its present level, a potential trigger for the Younger Dryas episode . </P> <P> Two ancient shorelines in the Toronto area mark the existence of former glacial lakes . About 2 km inland from the shore a ridge known as the Iroquois Shoreline can be discerned . The old shoreline runs west - east running roughly parallel to Davenport Road just south of St. Clair Avenue West . Further east, the Scarborough Bluffs also formed part of the shoreline of the ancient lake . </P> <P> Another ancient shoreline exists between 2--4 km offshore of Toronto . It is known as the Toronto Scarp and formed the shore of Glacial Lake Warren or Admiralty Lake . From Bluffer's Park in Scarborough to just west of Hanlan's Point is an underwater bluff . </P> <P> In New York, Ridge Road and New York State Route 104 run from west to east along a ridge of the old shoreline of Lake Iroquois . </P>

What evidence of a large glacial lake is there in northeastern ontario