Geologic Time Scale and Earth's Age

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Questions and Answers

What significant event is associated with the Archean Eon?

First fish appeared

Origin of multicelled organisms

First eukaryotes emerged (correct)

Dominance of trilobites

The Hadean Eon is known for the presence of life on Earth.

False

What technique uses fossils to establish the relative ages of rocks?

Biostratigraphy

The process of estimating the true age of a rock or fossil based on radioactive decay is known as __________ dating.

absolute Signup and view all the answers

Match the geological periods with their known features:

Hadean = No life known, cooling of Earth's crust Archean = First eukaryotes emerged Proterozoic = Origin of multicelled organisms and first sponges Phanerozoic = Trilobites dominated and first fish appeared Signup and view all the answers

Which period saw the appearance of modern humans?

Pleistocene Signup and view all the answers

The Jurassic period is known for the dominance of flowering plants.

False Signup and view all the answers

What type of mammals appear during the Paleocene period?

Early placental mammals Signup and view all the answers

The __________ major extinction event in the Permian caused the loss of 95% of marine species.

major Signup and view all the answers

Match the geological period with its notable characteristics:

Pliocene = First hominids appear Silurian = First spiders and jawed fish appear Cretaceous = Mass extinction of large animals Devonian = First amphibians and radiation of fish Signup and view all the answers

What was a significant characteristic of the Oligocene period?

Worldwide tropical rainforests Signup and view all the answers

The Eocene period is known for the dominance of reptiles.

False Signup and view all the answers

In which period did flowering plants first extensively radiate?

Pliocene Signup and view all the answers

What is the estimated age of the Earth?

4.6 billion years Signup and view all the answers

The oldest dated rock from the Earth is approximately 4.6 billion years old.

False Signup and view all the answers

What are fossils?

The remains and traces of plants and animals that have lived and died throughout the Earth's history. Signup and view all the answers

The __________ Time Scale is based on the rock record and divides geologic time into Eons, Eras, Periods, and Epochs.

Geologic Signup and view all the answers

Match the following geologic time intervals with their definitions:

Eon = The largest division of geologic time Era = A subdivision of an eon Period = A subdivision of an era Epoch = A subdivision of a period Signup and view all the answers

Which event marks the boundary between the Mesozoic Era and the Cenozoic Era?

The extinction of the dinosaurs Signup and view all the answers

The rock record is complete and preserves all events in Earth's history.

False Signup and view all the answers

What significant biological event occurred in the Quaternary period?

The rise of civilization and agriculture. Signup and view all the answers

Study Notes

Age of Earth and Geologic Time Scale

Earth's history spans 4.6 billion years.
Oldest dated Earth rock is ~3.8 billion years old.
Age determined through radioactive isotopic dating of meteorites.

Rocks and Fossils

Earth's history is recorded in rocks, but the record is incomplete.
Some events leave no record or are not preserved.
Rocks contain fossils—remains or traces of past life.
Fossils provide evidence for evolution (increasing complexity).

Geologic Time Scale

Timeline of Earth's history.
Divided into hierarchical intervals: Eon, Era, Period, Epoch.
Subdivisions based on significant events in Earth's history.
Determined by interpretations of the rock record.
Mass extinction event (dinosaurs) marks the boundary between the Mesozoic (Age of Reptiles) and Cenozoic (Age of Mammals).
This was a pivotal time in mammals' rise to dominance.

Establishing Geologic Time

Nicholas Steno (1638-1686) first recognized the connection between rocks and time. Principles like superposition, original horizontality, and lateral continuity are foundational in stratigraphy (study of layered rocks).
Relative dating techniques—early attempts by geologists to order rock layers by relative time, using the Principle of Superposition.
Werner's classification categorized rock-time units.
Fossils are essential tools; different fossils appear in specific rock strata, used in establishing correlation between rock units.
Smith's work with fossils allowed the subdivision of rock units. Lyell further refined the time correlation utilizing fossil evidence.

Fossil Importance

Fossils are key to understanding the geologic time.
Biostratigraphy is a sub-discipline of stratigraphy that uses fossils to correlate and establish relative ages of rocks.
Relative dating involves comparing events to determine chronologic order.

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Description

Explore the fascinating history of the Earth and the geologic time scale in this quiz. Learn about the age of the Earth, key events, and how fossil records contribute to our understanding of evolution. Test your knowledge on significant geological timelines and the pivotal moments in Earth's history.