Have you ever wondered how scientists think the Great Lakes wereformed? The answer to that starts with the ice age. Duringthe last ice age, there were large masses of ice calledglaciers. The last major glacier called the Laurentideformed. It covered almost all of Canada and extended to the UnitedStates as far as Chicago, Illinois. As it started melting andreceding, it pushed against the land and made big empty spaces. Allthe water that was left behind, called meltwater, filled thoseholes which made the Great Lakes. (This may help your child withhomework).
They were formed by glaciers applying pressureto the ground so theground weathered (broke down into small pieces) and the glaciermelted and that is the water.