Relative and Absolute Dating and Marker Fossils in Geologic Time
Science Simplifiedγ»6 minutes read
Earth's history spans 4.6 billion years, determined by radioactive dating of meteorites, with the oldest known rock at 3.8 billion years. Fossils in rock layers support evolution, while geologic time periods are defined by index fossils with distinctive features.
Insights
- Fossils found in rocks are crucial evidence for evolution, supporting the idea that life has become more complex over time, as proposed by Darwin.
- Stratigraphy, which involves studying layered rocks, is essential for understanding Earth's history, as it helps define geologic time periods using index fossils with distinct features and limited time ranges.
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Recent questions
How old is the Earth?
4.6 billion years old
What supports Darwin's theory of evolution?
Fossils
When did mammals dominate after a mass extinction?
66.4 million years ago
What aids in understanding Earth's history through rocks?
Stratigraphy
How are geologic time periods defined?
Index fossils
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Summary
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Earth's History: From Rocks to Fossils
- Geologic time spans 4.6 billion years, with the Earth's age determined by radioactive isotopic dating of meteorites, while the oldest known rock is 3.8 billion years old.
- The rock record, essential for understanding Earth's history, contains fossils providing evidence for evolution, supporting Darwin's theory of increasing life complexity over time.
- The geologic time scale divides time into intervals based on significant events, with the mass extinction leading to the dominance of mammals around 66.4 million years ago.
- Stratigraphy, studying layered rocks, aids in understanding Earth's history, with index fossils crucial for defining geologic time periods based on distinctive features and limited time ranges.
