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Questions and Answers
What is the Geologic Time Scale?
What is the Geologic Time Scale?
A tabular presentation of the history of life based on geologists' study of rocks and the fossils they contain.
What is the largest unit of geologic time?
What is the largest unit of geologic time?
Eon
What is the name of the current geological age?
What is the name of the current geological age?
The Phanerozoic Eon is the oldest Eon.
The Phanerozoic Eon is the oldest Eon.
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What is the second longest unit of geologic time?
What is the second longest unit of geologic time?
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What era does the Geologic Time Scale use to identify the time period when reptiles were dominant on Earth?
What era does the Geologic Time Scale use to identify the time period when reptiles were dominant on Earth?
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What era is considered the "Age of Mammals?"
What era is considered the "Age of Mammals?"
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The "Age of Fishes" is a period in the Paleozoic Era.
The "Age of Fishes" is a period in the Paleozoic Era.
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What is the basic unit of geologic time?
What is the basic unit of geologic time?
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What geologic time unit is often capitalized in a formal sense?
What geologic time unit is often capitalized in a formal sense?
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The Precambrian time period is also known as the "Age of Invertebrates"
The Precambrian time period is also known as the "Age of Invertebrates"
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The Permian-Triassic extinction event is one of the largest mass extinctions in Earth's history.
The Permian-Triassic extinction event is one of the largest mass extinctions in Earth's history.
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While the Geologic Time Scale (GTS) is a visual representation of Earth's history, it's more than just a timeline. What does the GTS really represent?
While the Geologic Time Scale (GTS) is a visual representation of Earth's history, it's more than just a timeline. What does the GTS really represent?
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Flashcards
Geologic Time Scale
Geologic Time Scale
A chronological representation of Earth's history based on rocks and fossils.
Eon
Eon
The broadest division of geological time, with four eons recognized.
Phanerozoic Eon
Phanerozoic Eon
The youngest eon, marked by abundant life forms and divided into three eras.
Era
Era
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Cenozoic Era
Cenozoic Era
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Paleozoic Era
Paleozoic Era
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Mesozoic Era
Mesozoic Era
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Period
Period
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Epoch
Epoch
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Ages
Ages
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Hadean Eon
Hadean Eon
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Archean Eon
Archean Eon
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Proterozoic Eon
Proterozoic Eon
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Pleistocene Epoch
Pleistocene Epoch
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Geologic Events
Geologic Events
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Rock Systems
Rock Systems
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Life Forms
Life Forms
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Relative Time Terms
Relative Time Terms
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Study Notes
Geologic Time Scale
- Represents Earth's history organized chronologically
- Based on geologists' study of rocks and fossils
- Arranged from the oldest (bottom) to most recent (top)
Divisions of Geologic Time
- Eons: Broadest divisions of time, characterized by four eons (Hadean, Archean, Proterozoic, and Phanerozoic)
- Eras: Longer spans of time within an eon, subdivided into periods (e.g., Paleozoic, Mesozoic, Cenozoic)
- Periods: Basic units of geologic time, lasting tens of millions of years, each period marking the time it takes to form a type of rock system
- Epochs: Subdivisions of periods, lasting several million years, marking the time a rock series is deposited, often further divided by early, middle, and late
- Ages: Referenced as "stages", lasting only a few million years, and an example of the present age is Meghalayan
Key Events and Life Forms
- Each segment is defined by major geologic events & appearance (and disappearance) of life-forms, starting with the formation of Earth's crust
- Precambrian eon encompasses Hadean, Archean, and Proterozoic eras and includes events like formation of the Earth's crust, oldest rocks, origin of life, early bacteria and algae, and the rise of complex multicelled organisms
- Paleozoic era (570-245 mya) is characterized by the evolution of invertebrates, fishes, and early terrestrial life forms, including extinction events and mountain building.
- Mesozoic era (245-65.5 mya) is known as the "Age of Reptiles" with dinosaurs as dominant life; includes extinction events and continental drift
- Cenozoic era (65.5 mya to the present) is the "Age of Mammals" with the rise of mammals and humans; encompasses North American events and extinction of large mammals
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Description
This quiz provides an overview of the geologic time scale, which organizes Earth's history chronologically based on geological and fossil records. Learn about the different divisions, including eons, eras, periods, epochs, and ages, along with key events and life forms that marked each segment.
