Show:
Relative Age
Fossils
Absolute Age
Geologic Time Scale
More Geologic Time Scale
100

The extinction of many species in a short period of time?

What is a mass extinction?

100
These are any remains, trace, or imprint of a living thing that has been preserved in Earth's crust.
What are fossils?
100

Scientists measure this to determine the exact age of fossils.

What are radioactive elements/half-life?

100

Earth's geological history on a chronological chart.

What does the geologic time scale represent?

100

This is how the Dinosaurs became extinct.

What are an asteroid impact and volcanic eruptions?

200
This idea states that lower layers of rocks in a series are older and upper layers of rocks are younger.
What is superposition?
200

Most often, fossils are formed in this.

What is sedimentary rock?

200
This is the time it takes for half of the mass of an original element to change into a new product.
What is Half-Life?
200

This is how long ago the Earth was formed.

What is 4.6 Billion Years ago?

200

This Era is known as "early life".

What is the Precambrian?

300

This is when magma hardens in rock layers.

What is an intrusion?

300
Specific fossils are the remains of living things that were widespread but only lived for a short period in Earth's history.
What are index fossils?
300
This is the age, in years, of a rock which is determined by comparing the amount of original element to the amount of decay product.
What is Absolute age?
300

This is the  largest division of geologic time.

What is Eon?

300

This Era is called "middle life" and included dinosaurs?

What is the Mesozoic?

400

Sometimes telling the relative age of rocks is not as simple as looking at the layers because the crust can do this over the course of time.

What is move, tilt, fold, crack, overturn? (any of these answers works) 

400

These are footprints or burrows left by ancient organisms .

What are trace fossils?

400

This is the amount of original element left after the first half-life passes.

What is 50%?

400

This was the longest Era.

What is Precambrian?

400

We are currently living in this Era.

What is the Cenozoic?

500

Most fossils form in this type of rock.

What is sedimentary rock?

500
The soft parts of organisms decay quickly, but fossils form out of the harder parts of the organism. These are 3 examples.
What are teeth, bones, shells, seeds, pollen grains, wooden stems. (name 3 for the points)
500

This is the other method of determining an age of a fossil that is not exact.

What is relative age?

500

A cold period when glaciers covered the Earth

What is the Ice Age?

500

This is the amount of major mass extinctions that Earth has experienced.

What is a total of "5"?