The Sahara Desert was once filled with rivers, giant lakes and hippos. Scientists explain why it turns green every 20,000 years

For most people, the Sahara is the ultimate symbol of endless sand, scorching heat and one of the harshest environments on ...
Nature

Green Sahara: African Humid Periods Paced by Earth's Orbital Changes

Paleoclimate and archaeological evidence tells us that, 11,000-5,000 years ago, the Earth's slow orbital 'wobble' transformed today's Sahara desert to a land covered with vegetation and lakes. Aa Aa ...
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A 26,000-year monument hidden at Hoover Dam

Monument Plaza at Hoover Dam features something most visitors walk right over without noticing: a terrazzo floor designed as a celestial map marking the dam's 1936 completion using Earth's axial ...