Key Events

• The Proterozoic Eon is a very active tectonic period.
• Evolutionary advances lead to multicellular organisms.
• Bacteria start to pump oxygen into the atmosphere, causing the ‘Great Oxygenation Event’.
• Life thrives in the oxygenated atmosphere and chemical processes change.
• Earth experiences its first glacial period around 2,450-2,220 million years ago, with a series of ice ages. There are several other glacial periods during the Proterozoic Eon.
• From 635 million years onwards, soft-bodied multicellular life (similar to jellyfish and worms) starts to emerge.

Facts, Debates & Trivia

• The Proterozoic Eon is named after the Greek word for ‘earlier life’
• Supercontinents form (e.g. Rodinia, around ~1,000-700 million years ago).
• Some scientists propose that the whole Earth becomes entirely covered in ice during periods of millions of years, up to around 650 million years ago (the ‘Snowball Earth’ hypothesis).
• On Mars, all liquid water dries up by 2,000 million years ago, leaving the cold, barren planet we see today.

Conditions

• Oxygen reacts with methane to create carbon dioxide.
• As concentrations of methane (a ‘greenhouse gas’ that is very effective at trapping heat) decrease, the temperatures fall.
• Iron is precipitated to make minerals like haematite.

Timeline

2,500-541 million years ago

(1,959 million years)

Where have you reached on the trail?