Show GREAT prehistoric LAKE lake agassiz was a body of fresh water that existed during a a late stage of the glacial epoch in the valley of red river and extended northward from the present head of that stream for nearly miles the area of the lake at the time tim of its greatest expansion was about qt square miles exceeding the present aggregate area of th the e five great lakes tributary to the st lawrence the shore of this ancient lake is marked by well defined beaches and it is from these that hat the existence and the ex extent bent of the lake are known the lake was named by the geologist warren upham in honor of 1 1 louis s agassiz who was the first to make a systematic study of glaciers and glacial phenomena |