Precambrian Flashcards
What is the Precambrian?
The Precambrian is the geological time period that covers the first 4.6 billion years of Earth’s history, preceding the Cambrian period.
True or False: The Precambrian is divided into three eons.
True
Name the three eons of the Precambrian.
Hadean, Archean, and Proterozoic.
Fill in the blank: The Hadean eon lasted from the formation of the Earth about _____ billion years ago to about 4 billion years ago.
4.6
What was the primary atmosphere composition of the early Earth during the Hadean eon?
It was composed mainly of hydrogen and helium, with little to no oxygen.
During which eon did the first solid crust form?
Archean eon.
Multiple Choice: Which of the following is NOT a characteristic of the Archean eon? A) Formation of first continents B) Presence of complex multicellular life C) Development of early life forms
B) Presence of complex multicellular life
What type of life forms first appeared during the Archean eon?
Prokaryotic microorganisms, such as bacteria and archaea.
True or False: The Proterozoic eon saw the first appearance of multicellular organisms.
True
What significant event marks the end of the Precambrian?
The Cambrian explosion, which began around 541 million years ago.
Name one major geological feature that formed during the Precambrian.
The supercontinent Rodinia.
Fill in the blank: The first evidence of photosynthesis is found in the _____ eon.
Archean
What is the significance of the Great Oxygenation Event?
It was a time when oxygen levels in the atmosphere significantly increased due to photosynthetic cyanobacteria, altering Earth’s environment and allowing for the evolution of aerobic organisms.
Multiple Choice: Which of the following organisms dominated the Proterozoic eon? A) Dinosaurs B) Jellyfish C) Trilobites
B) Jellyfish
What type of rock is most commonly associated with the Precambrian?
Igneous and metamorphic rocks.
True or False: The Precambrian is known for having a rich fossil record.
False
Fill in the blank: The oldest known rocks on Earth date back to the _____ eon.
Hadean
What is stromatolite?
Stromatolites are layered bio-chemical accretionary structures formed in shallow water by the activity of microorganisms, particularly cyanobacteria.
During which eon did the first multicellular life forms appear?
Proterozoic eon.
What is the term for the study of Earth’s history as recorded in rocks?
Geology.
