Topic 2 Earth History

Question 1

Earth is … years old

Answer 1

Earth is 4.6 billion years old

Question 2

Earth’s history is divided into …

Answer 2

Eons, eras, periods, and epochs

Question 3

What are Eons, eras, periods, and epochs based on?

Answer 3

Based on major geologic events (e.g. mass extinction - where atleast 75% of all species go extinct

Question 4

What is uniformitarianism?

Answer 4

The same processes that happen now happened in the past

Question 5

What is relative age?

Answer 5

Compares the age of one object or event to another without specifying dates (___ is older than ___)

Question 6

What is absolute age?

Answer 6

an age specified in years before the present

Question 7

What is the superposition principle?

Answer 7

Within layers of undisturbed, the older layers will be on the bottom and youngest are on top

Question 8

What is the crosscut principle?

Answer 8

When layers are disturbed by a feature cutting through one or more layers, the feature is younger than those being cut through

Question 9

What is Dendrochronology?

Answer 9

growth in trees where the oldest is near the core and the youngest growth is on the outside

Question 10

What is radiometric dating?

Answer 10

assigning an age to an object based on the radioactive half-life of unstable elements in those materials

Question 11

What is a half-life?

Answer 11

the time it takes for half the unstable elements to decay

Question 12

What is 14C Dating?

Answer 12

dating an object based on the 14c decay in organic materials

Question 13

What are the 3 principle layers of Earth’s interior?

Answer 13

the core, the mantle the lithosphere

Question 14

What is the inner core composed of?

Answer 14

solid iron and nickel

Question 15

What is the outer core composed of?

Answer 15

liquid iron and nickel

Question 16

How far below the surface does the inner core extend to?

Answer 16

~5000km

Question 17

How far below the surface does the outer core extend to?

Answer 17

~3000km

Question 18

How far below the surface does the lower mantle extend to?

Answer 18

~200km

Question 19

How far below the surface does the upper mantle extend to?

Answer 19

~100km

Question 20

How are Earth’s magnetic fields made?

Answer 20

The movement of liquid metal in the outer core generates electrical current

Question 21

What is the lower mantle made of?

Answer 21

heated and slowly deforming solid rock

Question 22

What is the upper mantle (asthenosphere) made of?

Answer 22

softer and weaker rock than the lower mantle

Question 23

How deep is the lithosphere?

Answer 23

surface level to ~100km

Question 24

How does the lithosphere sit on the upper mantle (asthenosphere)?

Answer 24

the lithosphere “floats” on top of upper mantle

Question 25

What is the continental crust mostly made of?

Answer 25

Granite

Question 26

What is the oceanic crust mostly made of?

Answer 26

Basaly

Question 27

What is the layer are the techtonic plates part of?

Answer 27

The lithosphere

Question 28

How many techtonic plates are there?

Answer 28

14 techtonic plates move over earth’s surface