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)