Volcanoe on a Cryogenian landscape in acid rain

Cryogenian period

A succession of incredibly harsh ice ages waxed and waned during the Cryogenian. It is nicknamed Snowball Earth as it's been suggested that the glaciation was so severe it may even have reached the equator. Life during the Cryogenian consisted of tiny organisms - the microscopic ancestors of fungi, plants, animals and kelps all evolved during this time.

Began: 850 million years ago

Ended: 635 million years ago

What the Earth was like

Causes of extinctions

During this period the following extinction level events are thought to have occurred.

Climate change Climate change
Earth's climate is not constant. Over geological time, the Earth's dominant climate has gone from ice age to tropical heat and from steamy jungles to searing deserts.

BBC News about Cryogenian period