The Sahara Had a Sea — And It's Coming Back.

More than 500 kilometers from the nearest open water, there's a cave painting of people swimming — in the middle of the Sahara Desert. NASA radar later found why: buried under the sand are entire river systems and a vanished sea roughly the size of Germany. Ten thousand years ago the Sahara was grassland with hippos, crocodiles, and a Stone Age cemetery of fishermen. Then it died — not from anything on the ground, but from a 21,000-year wobble in Earth's own spin, a cycle that's flipped the Sahara on and off more than 230 times. And the dust from the sea it left behind is still traveling across the Atlantic today, feeding the Amazon rainforest. Subscribe for more videos like this:    / @deepearthofficial   CHAPTERS 0:00 A Cave Painting of Swimmers, In a Desert 1:14 The Radar That Saw Through the Sand 3:13 Gobero: The Fishermen's Cemetery 4:43 Lake Mega-Chad, a Sea the Size of Germany 6:11 The Wobble: Earth's 21,000-Year Switch 8:21 How the Green Sahara Collapsed 10:19 The Water and Dust It Left Behind 12:27 The Next Green Sahara SOURCES & CREDITS Sound effects (SoundBible, Attribution 3.0): camera shutter, drilling, waterfall, wooden thump — Mike Koenig; counting tick — DeepFrozenApps; blop — Mark DiAngelo; large waterfall — Daniel Simion; wind — Mark DiAngelo Terrain: NASA Earth Observatory (Blue Marble: Next Generation); Esri, Maxar, Earthstar Geographics; GEBCO bathymetry Music: original score #GreenSahara #Sahara #Geology