The farm a billion years ago rough notes only
About 2.5 billion years ago Siberia was part of a continent called Arctica, along with the Canadian Shield. Around 1.1 billion years ago major tectonic changes seperated siberia from the Canadian sheild.
The third ice age, and possibly most severe, is estimated to have occurred from 720 to 635 Ma (million years) ago,[3] in the Neoproterozoic Era, and it has been suggested that it produced a second[4] “Snowball Earth“, i.e. a period during which Earth was completely covered in ice. It has also been suggested that the end of that second cold period[4] was responsible for the subsequent Cambrian explosion, a time of rapid diversification of multi-cellular life during the Cambrian Period. The hypothesis is still controversial,