Geological History of the Earth

1. Geological History of the Earth

2. Hadeon Eon • No rocks because the Earth was molten

3. Archean Eon • Earth’s crust cooled enough that rocks and continental plates began to form. • Two theories: • Because the Earth was hotter, plate tectonic activity was more vigorous than today and prevented cratonization and continent formation until the mantle cooled and convection slowed down • Because the mantle was too buoyant, subduction would not occur.

4. Proterozoic Eon • Featured massive, rapid continental accretion, supercontinent cycles, and orogenic activity. • Glaciations occurred

5. Phanerozoic Eon • Current eon—covers roughly 545 million years • Divided into three eras • Paleozoic • Mesozoic • Cenozoic

6. Paleozoic Era • Started shortly after the breakup of a supercontinent called Pannotia at the end of a global ice age • At the beginning, Earth’s landmass was broken up into a large number of small continents • Toward the end, the continents gathered together into a supercontinent called Pangaea

7. Mesozoic • Pangaea gradually split into a northern continent Laurasia and a southern continent, Gondwana • Later, Laurasia and Gondwana broke up into modern-day continents, but their locations were much different than they are today.

8. Cenozoic • Laurasia became North America and Eurasia • Gondwana split into South America, Africa, Australia, Antarctica and India, which collided with the Asian plate.

9. Pangaea Breaking Apart