Butterflies remember a mountain that hasn't existed for millennia:
The amazing part of the journey is the sudden eastward turn that monarchs take over Lake Superior. Monarchs fly over the lake, necessarily, in one unceasing flight. That alone would be difficult, but the monarchs make it tougher by not going directly south. They fly south, and at one point of the lake turn east, fly for a while, and then turn back toward the south. Why?Biologists, and certain geologists, believe that something was blocking the monarchs' path. They believe that that part of Lake Superior might have once been one of the highest mountains ever to loom over North America. It would have been useless for the monarchs to try to scale it, and wasteful to start climbing it, so all successfully migrating monarchs veered east around it and then headed southward again. They've kept doing that, some say, even after the mountain is long gone.