Formation and Evolution of Earth

Introduction

• Earth is unique, dynamic, and in a constant state of change.
• Key geological events: continental drift, volcanic eruptions, glacier movements.
• The focus of the lecture: the birth and formation of Earth from solar dust, the creation of oceans, the rise of life, and geological mysteries.

Initial Formation of Earth

• Earth formed from the dust of the solar system.
• Young sun surrounded by a cloud of dust and gas.
• Mineral grains in the solar dust cloud began to stick together due to static electricity, forming small rocks.
• Over millions of years, these rocks collided and grew bigger, eventually forming the Earth.

Geological Evidence and Challenges

• Meteorites provided clues to Earth's formation, being older than any Earth rocks.
• Earth's surface formations have been destroyed by geological processes over billions of years.
• Radiometric dating of meteorites helped determine Earth’s age.

Earth’s Age and Structure

• Early estimates of Earth's age based on biblical texts were inaccurate.
• Ernest Rutherford's method of using radioactive decay enabled accurate dating.
• C.C. Patterson used meteorites to determine Earth is approximately 4.5 billion years old.
• Earth’s structure: thin crust, massive mantle, iron-nickel core.

Impact Hypothesis and Moon Formation

• Early solar system had mini-planets; one collided with Earth, leading to the Moon's formation.
• The collision theory explains the Earth's and Moon's composition differences.

Formation of Continents and Oceans

• 200 million years post-formation: continents and oceans began forming.
• Evidence from Porpoise Cove, Canada suggests early Earth had a solid crust and oceans.
• Banded iron formations indicate underwater conditions, proving ancient ocean existence.

Origin of Earth’s Water

• Meteorites containing ancient water and salt grains suggest water was delivered via space rocks.
• Meteorite bombardment over billions of years filled Earth’s oceans.

Origin of Life and Oxygen

• Cyanobacteria in stromatolites were early life forms that produced oxygen.
• Stromatolites are evidence of microbial life contributing to Earth's atmosphere.
• Cyanobacteria's production of oxygen eventually allowed for complex life forms to evolve.

Conclusion

• Earth formed 4.5 billion years ago, developing continents, oceans, and life forms.
• Life’s evolution and geological processes have shaped the planet we inhabit today.
• The investigation into Earth’s formation reveals the critical role of meteorites in delivering water and life's building blocks.