Snowball Earth: the big freeze

In this video, Dr Ernest Chi Fru explains how on at least three occasions Earth was completely frozen over and covered in ice.

It is hard for us to envisage this and to grasp how Earth went from this extreme icy state to our current climate.

Evidence for Snowball Earth

Evidence has been found in the rock fragments (tillites) carried by moving ice, and pebbles and boulders (dropstones) carried and deposited by icebergs.

This evidence has been found by geologists across the world.

Theory of Snowball Earth

Whilst evidence has been found, the theory of Snowball Earth is still a relatively new scientific hypothesis, and large uncertainties on its causes remain.

This makes it an exciting research topic in Earth sciences today, attracting the attention of many top researchers.

Due to their sheer scale Snowball Earth ice ages were extreme events, but what possible link could they have to the emergence of life?