But now that the ice is gone, the crust is popping back up. The rebound more than 6,000 years ago elevated the outlets draining across Canada so that flow had to be redirected southward, following the current pattern of Great Lakes drainage. Lake level in Lake Michigan is a mirror image of temperature. Lake level falls. When it is cool, there is an increase in precipitation and a reduction in evaporation.
Lake level rises.
It is possible then that coming out of the Hypsithermal there was increased precipitation and less evaporation across the basin. This would have caused lake level to rise. Gary, East Chicago, the northern part of Hammond, Miller, Ogden Dunes, Dune Acres, Beverly Shores and the north part of Michigan City were under water. Of course they were not there then because the Toleston Beach had not yet been created. That, however, is the rest of northwestern Indiana's story.