Lava flows shaped the basins that formed the great lakes.
a. true
b. false

B. False

Explanation:

The basins of the Great Lakes have not been shaped by lava flows, but instead they have been shaped by glaciers. The Great Lakes are relatively new lakes. Until relatively recently, more specifically, until the end of the last ice age, that area was covered in a very thick layer of ice, or rather glaciers. As the glaciers were pressing the crust with their weight, as well as causing erosion with their movement, they managed to create the basins of the Great Lakes. Once the climate warmed, and the glaciers started to melt, the basins got filled with water from them, thus creating the Great Lakes that we see in the present.

heat from the core of the earth causes convection currents to occur in the mantle. these currents slowly move the crust around.