Michigan Test for Teacher Certification (MTTC) Secondary Integrated Science Practice test

What defines an epoch in geological time?

1. It is a brief period of drastic climate change

2. It is a division characterized by significant evolutionary developments

3. It marks the complete shift in Earth's climate

4. It is defined solely by human activity

The correct answer is: It is a division characterized by significant evolutionary developments

An epoch in geological time is defined as a division characterized by significant evolutionary developments. This means that during an epoch, there are notable changes in the types and diversity of organisms present on Earth, often linked to various environmental factors and biological advancements. Epochs are subdivisions of periods on the geological time scale and represent intervals where significant evolutionary milestones occur, such as the emergence of new species or major changes in ecosystems. In contrast, while brief periods of drastic climate change might influence an epoch, they do not solely define it. Furthermore, while significant shifts in Earth’s climate can occur during an epoch, these changes do not encompass the full definition of an epoch. Additionally, the influence of human activity on geological time has led to discussions of the Anthropocene, but defining an epoch solely by human activity overlooks the broader evolutionary context that characterizes epochs throughout Earth’s history.