Geological Time Basics
It’s the system that divides Earth’s 4.6-billion-year history into eons, eras, periods, and epochs.
What is the Geological Time Scale (GTS)?
This eon means “visible life” and includes most complex organisms.
What is the Phanerozoic Eon?
The number of major mass extinction events.
What is five?
The time when Earth first formed from dust and gas in the solar system.
What is the Hadean Eon?
What helped the scientists to build the geological time scale.
What are rock layers (stratigraphy) and fossils?
The Paleozoic Era is often called this because of the explosion of marine life.
What is the “Age of Marine Life”?
The End Ordovician extinction wiped out 86% of species due to these extreme climate swings.
What are glacial and interglacial periods (freezing and warming)?
The eon when oxygen began to build up in Earth’s atmosphere, allowing multicellular life to form.
What is the Proterozoic Eon?
This dating method measures radioactive decay to determine a rock’s age.
What is radiometric dating?
Dinosaurs ruled during this middle era of the Phanerozoic Eon.
What is the Mesozoic Era?
The End Permian extinction, the deadliest one, was triggered by massive volcanic activity here.
What is Siberia?
A burst of life in the oceans during the Paleozoic Era that produced many new species.
What is the Cambrian Explosion?
Arrange these from longest to shortest: Period, Eon, Epoch, Era.
What is Eon → Era → Period → Epoch?
Mammals and humans appeared during this most recent era.
What is the Cenozoic Era?
This extinction at 65 million years ago was caused by an asteroid that hit Yucatán, Mexico.
What is the End Cretaceous extinction?
This event ended the Mesozoic Era and wiped out the dinosaurs.
What is the End Cretaceous extinction (asteroid impact)?
This eon marks the formation of Earth and is the oldest division of time.
What is the Hadean Eon?
These four eons, from oldest to newest, make up Earth’s history.
What are Hadean, Archean, Proterozoic, and Phanerozoic?
This extinction happened about 360 million years ago when land plants caused rapid global cooling.
What is the Late Devonian extinction?
Humans appeared during this period of the Cenozoic Era.
What is the Quaternary Period?