Ancient EarthPAGE 31 OF INB

Essential Question:

How did the oceans and Atmosphere form?

THE PRESENT IS THE KEY TO THE

PAST.

Review:

How did the Earth form?What is the driving force behind the Nebular theory?

What do you think the Earth was like?

Hadean Eon: first 640 my

Extremely Hot: Asteroids and Radioactive decay.

Surface was covered with molten seasAny land that formed was quickly destroyed.

Hadean Eon: first 640 my

Atmosphere: water vapor, Carbon Dioxide, poisonous gases.NO OXYGEN!!!!

Similar to gases admitted by volcanos today.

Archean Eon: 4 – 2.5 mya

Interior 2x as hot as todayFirst long lasting surfaces, some still

around. (oldest rocks)Lots of small chunks of land called

protocontinentsConvection currents moved the plates like

today, but faster.

Archean Eon: 4 – 2.5 mya

First oceans form.Salty due to acid rainFirst critters: unicellular bacteria and Cyanobacteria (blue/green algae)

Formed mounds called Stromatolites.