Geological History of the Earth

Hadeon Eon No rocks because the Earth was molten

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.

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

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

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

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.

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

Pangaea Breaking Apart