Evidence of Ice Sheet Evolution
qThis figures shows a North Atlantic Ocean sediment core holds a 3 Myr d18O record of
ice volume and deep-water temperature
changes.
qThere were no major ice sheets before 2.75 Myr ago.
qAfter
that, small ice sheets grew and melted at
cycles of 41,000 and 23,000 years
until 0.9 Myr ago.
qAfter 0.9 Myr ago, large ice sheet grew and melted at a cycle of 100,000 years.
(from
Earth’s Climate: Past and Future)