Deep TimeCosmos & Earth

Ozone layer forms

600 million years agoNotable

Accumulating oxygen creates an ozone shield that blocks ultraviolet light, making land habitable.

Longest chain: The Big Bang → First stars ignite → Supernovae seed heavy elements → The Sun forms → Earth forms → First oceans → First life → Photosynthesis evolves → Great Oxidation Event → Ozone layer forms

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BookRobert M. Hazen

The Story of Earth ↗