Evidence that there was much more land ice about 20,000 years ago than there is now includes:
a) land bearing the unique marks of glaciers is sinking today, while regions just around that land are rising as deep hot rock flows back after being displaced by the glaciers. b) river valleys have cut down rapidly over the last 20,000 years, draining coastal embayments. c) 20,000-year-old deceased shallow-water corals occur in growth position far above modern sea level on the sides of oceanic islands. d) shells of creatures that lived in the ocean about 20,000 years ago indicate that the ocean water was especially isotopically heavy then. e) immense volumes of diet pepsi were forced into subglacial aquifers by the weight of the overlying ice, serving as the modern source of all the diet pepsi sold at penn state.