When Earth Was a Snowball: The Coldest Winter in Earth’s History

Sea ice from the beach to the horizon — on the equator. For millions of years Earth was a frozen white planet, and the rock record can prove it. 717 million years ago glaciers reached the sea at the equator, and the ice held for about 56 million years. The proof sits in plain rock: dropstones punched into quiet sea-floor mud, fossil compass needles lying flat in Australian strata, iron that only builds up in an ocean sealed from the air, and pale cap carbonates that only a sudden hothouse could pour over a glacier. From Svalbard to Namibia to Death Valley, the clues line up into two global freezes of the Cryogenian — and the thaw that made room for the first animals. Which clue convinced you most — the dropstones, the flat compass needles, or the cap carbonate in Namibia? Tell me in the comments, and subscribe for more deep-time films. Chapters: 0:00 Sea Ice on the Equator 2:08 A Tillite on Svalbard 3:40 Glacial Rubble on Every Continent 5:08 Magnetic Grains as a Fossil Compass 7:37 Was Earth's Axis Tipped Over? 8:59 Budyko's Runaway Ice Model 10:44 Minus Fifty Degrees and No Rain 12:09 Volcanoes, CO2 and the Way Out 14:15 Red Iron Bands in the Mackenzies 15:51 Rodinia Breaks Up, Basalt Weathers 17:46 A Sun Six Percent Dimmer 19:21 Cap Carbonate Over Tillite in Namibia 21:44 Carbon Isotopes Record the Shutdown 23:24 The Cryogenian and the Sturtian Freeze 24:46 The Marinoan and an Older Snowball 26:39 How Life Survived the Ice 29:22 Algae Take Over the Oceans 30:39 The Golden Spike at Enorama Creek 32:49 Did the Freezes Clear the Way? 34:11 Snowball Earth Sites You Can Visit 35:05 Seven Clues for a Frozen Planet #SnowballEarth #Cryogenian #DeepTime #Geology Archive sources: • https://commons.wikimedia.org/wiki/Fi... (Kaspars Dzenis, CC BY 3.0) • https://commons.wikimedia.org/wiki/Fi... (SLAMMER!, CC BY 3.0) • https://commons.wikimedia.org/wiki/Fi... (Sherp ET, CC BY 3.0) • https://commons.wikimedia.org/wiki/Fi... (Aarhus Universitet, CC BY 3.0) • https://commons.wikimedia.org/wiki/Fi... (r00t burn, CC BY 3.0)