The Ice Ages

3.3 Ma – ongoing43 items

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Woolly mammoths, horses, a woolly rhinoceros and cave lions in northern Spain during the last glacial period. Painting: Mauricio Antón, c. 2004. CC BY 2.5, via Wikimedia Commons.
Woolly mammoths, horses, a woolly rhinoceros and cave lions in northern Spain during the last glacial period. Painting: Mauricio Antón, c. 2004. CC BY 2.5, via Wikimedia Commons.

Three million years of ice

For the last three million years the Earth has swung between glacials, when ice sheets kilometres thick covered Canada and Scandinavia and the sea fell by more than a hundred metres, and short warm interglacials like the one we live in now. The rhythm is set by small wobbles in Earth’s orbit.

How to read it

  • Glacials and interglacials as bands — the 41,000-year world, the switch to 100,000-year cycles, and the marine isotope stages (MIS) that tell the story: MIS 11, the Eemian, the Last Glacial Maximum and the Holocene

  • The zoom tightens from millions of years at the start to centuries at the end, when the Younger Dryas, the Storegga slide and the drowning of Doggerland can be told almost generation by generation

  • How we know — the last items step out of deep time into the calendar: Agassiz, Milankovitch, the ocean cores and the ice cores of Greenland and Antarctica

Threads to follow

  • ice — ice sheets growing and collapsing

  • sea level — Beringia, Sundaland and Doggerland

  • floods — megafloods, drained lakes and a tsunami

  • orbital cycles — the pacemaker

  • ice cores — the archive in the ice

Dates are in years before present, counted from 1950; ice-core ages, which are published as years before 2000, are converted. Epochs follow the International Chronostratigraphic Chart.

It is concluded that changes in the earth’s orbital geometry are the fundamental cause of the succession of Quaternary ice ages. — Hays, Imbrie and Shackleton, “Pacemaker of the Ice Ages”, 1976

Items

  1. Mid-Pliocene Warm Period

    ≈ 239 thousand years

  2. ≈ 275 thousand years

  3. The 41,000-year world

    ≈ 1.45 million years

  4. Ice sheets spread across the north

  5. Pleistocene

    ≈ 2.57 million years

  6. The Quaternary begins

    Monte San Nicola, near Gela, Sicily

  7. Ice reaches Missouri

    Glacial tills of northern Missouri

  8. Mid-Pleistocene Transition

    ≈ 550 thousand years

  9. Brunhes–Matuyama reversal

    Chiba section, Yoro River, Ichihara, Japan

  10. The 100,000-year world

  11. MIS 12: the Anglian glaciation

    ≈ 54 thousand years

  12. A megaflood breaks the Dover Strait

    Strait of Dover

  13. MIS 11: the long interglacial

    ≈ 50 thousand years

  14. MIS 6: the penultimate glaciation

    ≈ 61 thousand years · Utrechtse Heuvelrug, a Saalian push moraine, Netherlands

  15. Eemian interglacial (MIS 5e)

    ≈ 13 thousand years · River Eem, Amersfoort, Netherlands

  16. Hippos in the Thames

    Trafalgar Square, London

  17. Last glacial period

    ≈ 103 thousand years

  18. Beringia land bridge

    ≈ 24.7 thousand years · Bering land bridge, now the Bering Strait

  19. Last Glacial Maximum

    7,500 years

  20. Laurentide ice sheet at its greatest

    Laurentide ice sheet, rough extent at its maximum

  21. Fennoscandian ice sheet at its greatest

    Fennoscandian ice sheet, rough extent at its maximum

  22. Sundaland at its largest

    Sunda Shelf, between Sumatra, Borneo and Java

  23. Doggerland

    ≈ 11 thousand years · Doggerland, now the southern North Sea

  24. Missoula floods

    3,000 years · Dry Falls, Channeled Scablands, Washington

  25. Bølling–Allerød warming

    1,790 years

  26. Meltwater pulse 1A

    Fossil reefs off Tahiti, where the pulse was measured

  27. Lake Agassiz

    5,300 years · Lake Winnipeg, the largest remnant of Lake Agassiz

  28. Younger Dryas

    1,200 years

  29. Holocene

  30. The Holocene begins

    NorthGRIP drill site, Greenland ice sheet

  31. The 8.2 ka event

    150 years

  32. Lake Agassiz drains into Hudson Bay

    Hudson Bay

  33. The Storegga slide

    Storegga slide scar, off Møre, Norway

  34. Doggerland’s last islands go under

    Dogger Bank, North Sea

  35. The last mammoths die out on Wrangel Island

    Wrangel Island, Arctic Ocean

  36. Agassiz proclaims an ice age

    Neuchâtel, Switzerland

  37. Bretz defends the Scablands flood

    Washington, DC

  38. The trawler Colinda nets a harpoon

    Between the Leman and Ower banks, off Norfolk

  39. Milankovitch’s Canon of insolation

  40. “Pacemaker of the Ice Ages”

  41. GRIP reaches bedrock at Summit

    GRIP drill site, Summit, Greenland

  42. Vostok: four glacial cycles

    Vostok Station, East Antarctica

  43. EPICA Dome C: eight glacial cycles

    Concordia Station, Dome C, Antarctica

  44. Beyond EPICA reaches bedrock

    Little Dome C, Antarctica