Podcast
Questions and Answers
Which eon is characterized by the appearance of the first bacteria in the oceans and an atmosphere lacking oxygen?
Which eon is characterized by the appearance of the first bacteria in the oceans and an atmosphere lacking oxygen?
- Proterozoic Eon
- Cambrian Period
- Ordovician Period
- Archean Eon (correct)
The Cambrian Explosion refers to a sudden increase in volcanic activity during the Cambrian Period.
The Cambrian Explosion refers to a sudden increase in volcanic activity during the Cambrian Period.
False (B)
What significant event led to oxygen beginning to fill the atmosphere during the Proterozoic Eon?
What significant event led to oxygen beginning to fill the atmosphere during the Proterozoic Eon?
photosynthesis by bacteria
The first jawed fish appeared during the __________ Period.
The first jawed fish appeared during the __________ Period.
Match the geological period with its corresponding event:
Match the geological period with its corresponding event:
During which period did the first land plants begin to spread, contributing to a greener Earth?
During which period did the first land plants begin to spread, contributing to a greener Earth?
The formation of the first coral reefs occurred during the Silurian Period.
The formation of the first coral reefs occurred during the Silurian Period.
What type of animals with hard shells were abundant in the oceans during the Cambrian Period?
What type of animals with hard shells were abundant in the oceans during the Cambrian Period?
A significant ice age that caused a massive extinction occurred during the __________ Period.
A significant ice age that caused a massive extinction occurred during the __________ Period.
Which of the following characteristics describes the sky's appearance during the Archean Eon?
Which of the following characteristics describes the sky's appearance during the Archean Eon?
Flashcards
Proterozoic Eon
Proterozoic Eon
The eon from 2.5 billion to 541 million years ago, marked by oxygen production by bacteria, the first multicellular life, and soft-bodied animals.
Archean Eon
Archean Eon
The eon from 4 to 2.5 billion years ago, characterized by a hot Earth and the first appearance of bacteria in the oceans.
Cambrian Period
Cambrian Period
A period from 541 to 485 million years ago, known for a rapid diversification of marine life, including the first fish and many shelled creatures.
Ordovician Period
Ordovician Period
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Silurian Period
Silurian Period
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Study Notes
- The focus spans from the Archean Eon to the Silurian Period.
Archean Eon
- This Eon occurred 4 to 2.5 billion years ago.
- Earth was very hot during this time.
- The first tiny life forms (bacteria) appeared in the oceans.
- There was no oxygen to breathe yet.
- The sky appeared orange.
Proterozoic Eon
- This Eon occurred 2.5 billion to 541 million years ago.
- Oxygen started filling the air because of bacteria doing photosynthesis.
- The first simple multicellular life forms appeared.
- Towards the end, the first soft-bodied animals showed up.
Cambrian Period
- This period occurred 541 to 485 million years ago.
- There was a "Cambrian Explosion" which saw a boom of new animals, including the first fish.
- Many animals had hard shells, like trilobites.
- Earth’s oceans teemed with strange creatures.
Ordovician Period
- This period occurred 485 to 443 million years ago.
- The first coral reefs formed.
- Early fish developed armor-like plates.
- Some tiny plants started growing on land.
- A huge ice age caused a massive extinction.
Silurian Period
- This period occurred 443 to 419 million years ago.
- The first jawed fish appeared.
- Land plants spread, greening the Earth.
- Early scorpions and insects started crawling on land.
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