Early Earth History

The Era when life began was...

• cenozoic
• paleozoic
• mesozoic
• precambrian

The longest Era was...

• Precambrian
• Paleozoic
• Mesozoic
• Cenozoic

Cyanobacteria created this gas during the Precambrian Era.

• Carbon Dioxide
• Hydrogen
• Nitrogen
• Oxygen

Paleozoic is an example of_________.

• an epoch
• an era
• a period
• an eon

What came first?

• Paleozoic
• Mesozoic
• Cenozoic
• Precambrian

How old is the Earth?

• 46 billion years
• 4 billion years
• .46 billion years
• 4.6 billion years

About how much of Earth's history is made up of the Precambrian time?

•  88% 
• 12%
• 2%
• 50%

Why are fossils rarely found in Precambrian rock?

• There was no evidence of life in Precambrian time
• Rocks from Precambrian have yet to be discovered.
• Most Precambrian organisms did not have hard body parts that commonly form fossils.
• Precambrian rock is buried too deeply for geologists to study it. 

Where did life originally form?

• land
• oceans
• atmosphere
• center of Earth

The oldest rocks on Earth are_______________.

• 1.6 million years old
• 3.5 million years old
• 1-2 billion years old
• 3.8 to 3.96 billion years old