Cryogenian period

Definition

The Cryogenian period is a geologic time frame that occurred approximately 720 to 635 million years ago, characterized by extensive glaciations. It played a crucial role in shaping the early evolution of multicellular life.

5 Must Know Facts For Your Next Test

1. The Cryogenian period experienced two major glaciation events known as Sturtian and Marinoan glaciations.
2. It is often referred to as 'Snowball Earth' due to the severe ice ages that potentially covered the entire planet in ice.
3. The end of the Cryogenian period set the stage for the emergence of complex multicellular organisms in the Ediacaran period.
4. Geological evidence from this period includes dropstones and glacial deposits found on nearly every continent.
5. Cryogenian glaciations may have triggered evolutionary pressures that led to increased diversity and complexity in early animal life.

Review Questions

• What are the names of the two major glaciation events during the Cryogenian period?
• Why is the Cryogenian period often referred to as 'Snowball Earth'?
• How did the Cryogenian period influence the evolution of multicellular organisms?

Related terms

Ediacaran Period: A geologic time frame following the Cryogenian, marked by an increase in complex multicellular life forms.

Sturtian Glaciation: One of the two major glaciation events during the Cryogenian period, occurring around 717 to 660 million years ago.

Marinoan Glaciation: The second major glaciation event of the Cryogenian period, occurring around 650 to 635 million years ago.