Geological History of the EarthGeological History of the Earth

Hadeon EonHadeon Eon

• No rocks because the Earth was molten

Archean EonArchean 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 EonProterozoic Eon

• Featured massive, rapid continental accretion, supercontinent cycles, and orogenic activity.

• Glaciations occurred

Phanerozoic EonPhanerozoic Eon

• Current eon—covers roughly 545 million years

• Divided into three eras– Paleozoic– Mesozoic– Cenozoic

Paleozoic EraPaleozoic 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

MesozoicMesozoic

• 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.

CenozoicCenozoic

• Laurasia became North America and Eurasia

• Gondwana split into South America, Africa, Australia, Antarctica and India, which collided with the Asian plate.

Pangaea Breaking ApartPangaea Breaking Apart