Earth: A Journey Through Time

Introduction

• Earth is 4.5 billion years old.
• Conceptualize Earth's history as a 1-hour train ride where every second represents 1.5 million years.

Hadean Eon (4.5 Billion Years Ago)

• Earth began as a hellish lava planet.
• Collision with Theia formed the Moon.
• Atmosphere: Mostly CO2; surface was lava.
• Sun 30% less bright; greenhouse gases kept Earth warm.
• Life possibly began, first cells might have appeared.

Archean Eon

Paleoarchean (3.6 Billion Years Ago)

• Early supercontinents forming underwater.
• Stromatolites: first evidence of life.
• Photosynthesis might have started.

Mesoarchean (3.2 Billion Years Ago)

• Era of continents begins, tectonic activity.
• Oceans hot (~40°C), life expands (no plants, no oxygen).

Neoarchean (2.8 Billion Years Ago)

• Prokaryotes like bacteria colonize Earth.

Proterozoic Eon

Siderian (2.5 Billion Years Ago)

• Great Oxidation Event begins.
• Oxygen in atmosphere, first ice ages.

Rhyacian (2.3 Billion Years Ago)

• Volcanic activity thaws Earth.
• Continued evolution of life.

Orosirian (2.05 Billion Years Ago)

• Large asteroid impact; mountain ranges form.

Statherian (1.8 Billion Years Ago)

• Supercontinent Columbia forms.
• Natural nuclear reactors due to uranium deposits.

Calymmian (1.6 Billion Years Ago)

• First Eukaryotic cells appear.
• Earth's crust thickens, fungi-like organisms emerge.

Ectasian (1.4 Billion Years Ago)

• Earth's inner core begins to form.

Stenian (1.2 Billion Years Ago)

• Algae invent sexual reproduction.

Neoproterozoic Eon

Tonian (1 Billion Years Ago)

• Unicellular predators emerge.
• Microbial diversity increases.

Cryogenian (720 Million Years Ago)

• Earth undergoes another freeze.

Ediacaran (635 Million Years Ago)

• Supercontinent Gondwana forms.
• Multicellular organisms become widespread.

Phanerozoic Eon

Cambrian (539 Million Years Ago)

• Cambrian explosion: variety in life forms.
• First major mass extinction.

Carboniferous (359 Million Years Ago)

• Peak of forests and marshlands.
• Formation of coal deposits.

Permian (299 Million Years Ago)

• Formation of supercontinent Pangea.
• Largest mass extinction event.

Triassic (252 Million Years Ago)

• Age of reptiles begins; dinosaurs emerge.

Cretaceous (66 Million Years Ago)

• Asteroid impact causes dinosaur extinction.

Paleogene (66 Million Years Ago)

• Mammals become dominant.
• Human history begins.

Conclusion

• Earth is ancient; humanity is relatively recent in its history.
• The project is a culmination of years of work, celebrating a 10-year anniversary.
• Encouragement to support educational content and explore further resources, like the Timeline of Evolution poster.