Geologic time as a calendar; how rocks and fossils build the timeline of Earth.

Hadean to Archean bands show oceans, continents, and the first simple life emerging.

Cyanobacteria oxygenate oceans and atmosphere, reshaping life and climate on Earth.

Phanerozoic ignition as animals diversify with shells, predators, and complex bodies.

Paleozoic to Mesozoic; plants and reptiles rise, then asteroid-driven extinction opens niches.