Introduction

Question 1

What word describes the structure of the Earth?

Answer 1

Concentric (Circles around each other)

Question 2

What are the 3 primary layers to the structure of the Earth?

Answer 2

Core
Mantle
Crust

Question 3

What % of Earth’s volume is the mantle?

Answer 3

84%

Question 4

Average thickness of the mantle?

Answer 4

2 886 km deep

Question 5

Mineral composition of the mantle:

Answer 5

Rich in magnesium and iron

Question 6

What form is the mantle in?

Answer 6

Mostly solid -> behaves in time like a viscous fluid

Question 7

What part of the mantle is the mesosphere and what part is the asthenosphere?

Answer 7

Mesosphere: Lower mantle
Asthenosphere: Upper mantle

Question 8

What ‘sphere’ is directly above the asthenosphere?

Answer 8

Lithosphere (crust)

Question 9

Average thickness of continental and oceanic crusts:

Answer 9

Continental: 35 km
Oceanic: 5 km

Question 10

Which crust is heavier?

Answer 10

Oceanic

Question 11

Which crust is older?

Answer 11

Continental

Question 12

What is the mantle-crust boundary known as?

Answer 12

Mohorovicic Discontinuity (Moho)

Question 13

Define discontinuity:

Answer 13

Surface whereby seismic waves change their velocity

Question 14

How was the Moho Discontinuity identified?

Answer 14

P waves have faster velocity above Moho than below

Question 15

What is the core-mantle boundary known as?

Answer 15

Gutenberg Discontinuity

Question 16

How do we know about the Gutenberg Discontinuity?

Answer 16

P waves decrease in velocity, S waves disappear altogether (cannot travel through liquid)

Question 17

Where do convection currents (which sphere) occur and what causes them?

Answer 17

Asthenosphere

Heat from mantle causes convection currents

Question 18

What causes the lithosphere and crust to move?

Answer 18

Deep and shallow convection currents
Deep: Gutenberg Discontinuity
Shallow: Convection currents in upper mantle

Question 19

What is Ridge Push?

Answer 19

Lava eruptions form ocean ridges at constructive boundaries -> weighs down on plates and forces them to move apart

Question 20

What is Slab Pull?

Answer 20

Subducted crust as destructive boundaries pulls the rest of the plate with it

Question 21

Evidence for plate tectonic theory: 1801

Answer 21

Alexander van Humboldt -> Looked like a jigsaw fit (South America, Africa)

Question 22

Evidence for plate tectonic theory: 1912

Answer 22

Wegener’s Continental Drift Theory (Pangaea)

Question 23

Why was Wegener’s theory not believed?

Answer 23

He had evidence but couldn’t explain why it happened

Question 24

Evidence for plate tectonic theory: 1919

Answer 24

Holmes: Convection currents in mantle move continents

Question 25

Evidence for plate tectonic theory: 1950s

Answer 25

Sea floor spreading (magnetic striping on ocean floor)