Plate Tectonics

Question 1

What is the lithosphere?

Answer 1

The solid outer part of the Earth, consisting of part of the upper mantle and the crust

Question 2

What is the athenosphere?

Answer 2

The layer below the lithosphere, it is plastic, meaning its a weak solid, with some properties of a liquid

Question 3

How do we know that sea floor isn’t flat?

Answer 3

Harry Hess used sonar to detect it

Question 4

Who came up with the theory of continental drift?

Answer 4

Alfred Wegner

Question 5

What is continental drift?

Answer 5

A theory that the continents weren’t fixed, but they were moving, and that they had once formed Pangea, a super continent.

Question 6

How did Alfred Wegner come up with the continental drift theory?

Answer 6

The close geographical fits of the different continents which he described as like a torn newspaper, narrow mountain belts restricted to continental margins and the distribution of fossils

Question 7

What was the massive difference between the continental drift theory and the previous theories?

Answer 7

They all said the continents were fixed, but continental drift said they moved around

Question 8

What is the structure of the Earth?

Answer 8

Crust(solid), upper mantle(solid), lower mantle(plastic), outer core(liquid) and inner core(solid)

Question 9

What is the difference between plate tectonics and continental drift?

Answer 9

The continental drift theory said that the continents were moving, where as with plat tectonics the continents are on moving plates

Question 10

How did we come up with the theory of plate tectonics?

Answer 10

Alfred Wegner noticed that South America and Africa was like a torn newspaper, that narrow mountain belts were restricted to continental margins and that the distribution of fossils on different continents. Harry Hess found out about sea floor spreading and the dating of rocks from the sea floor.

Question 11

Which are denser, oceanic or continental plates?

Answer 11

Oceanic

Question 12

What are the three types of boundaries?

Answer 12

Divergent, convergent and transform

Question 13

What is a divergent boundary?

Answer 13

Two plates move apart, and a crack is made which is called a rift valley, and volcanic eruptions then create new crust. They are also called constructive boundaries

Question 14

What are convergent subduction boundaries?

Answer 14

When an oceanic plate and a continental plate move towards each other, and the oceanic plate, being denser, sinks under the continental plate. A deep trench is formed, earthquakes are felt along the boundaries and volcanoes form

Question 15

What happens at a convergent island chain boundary?

Answer 15

When 2 oceanic plates collide subduction occurs, and the faster moving moves under the other. A deep trench is formed, earthquakes are felt, and newly formed volcanoes create islands

Question 16

What happens at convergent mountain range boundaries?

Answer 16

Two continental plates collide, and the force pushes both plates upwards. A high narrow belt of mountains is formed

Question 17

What happens at a transform boundary?

Answer 17

Two plates slide against each other. It causes earthquakes

Question 18

What does convection and plate tectonics have to do with each other?

Answer 18

Convection in the asthenosphere moves the plates

Question 19

What is slab pull?

Answer 19

The plate at subduction zones are denser then those near mid ocean ridges, so gravity pulls the heavy, dense plate downwards into the subduction zone. This then pulls the plate into the trench and away from the ocean ridges. The end result is that the plates are pulled apart.

Question 20

What is ridge push?

Answer 20

Since the new ocean crust is forming at the ridges it is above the rest of the crust, gravity pulls the new crust downwards. This would push on the older crust below it and to its sides. This force may be enough to move the plate sideways.

Question 21

What are rifts?

Answer 21

The cracks down the middle of diverging plates

Question 22

What is the Great Global Rift System?

Answer 22

The under water mountain system

Question 23

What is rifting?

Answer 23

The theory for how the continents broke up; the crust cracked and subsided and water filled the gap.

Question 24

What happens at transform boundaries to cause earthquakes?

Answer 24

Slow moving plates suddenly slip past past each other quickly

Question 25

What do GPS ground systems do?

Answer 25

Send messages to satellites about how far the Earth moves and in which direction.

Question 26

How do divergent boundaries create volcanoes?

Answer 26

They create weaknesses in the crust and magma find its way through the weaknesses

Question 27

How does subduction cause volcanoes?

Answer 27

The plates are weakened and a lot of heat is created, so volcano chains form

Question 28

Where do hotspots occur?

Answer 28

Where the crust is weak

Question 29

What are earthquakes measured with?

Answer 29

Seismometers, which draw waves by having a pen that moves with vibrations and draws a seismograph

Question 30

What are earthquakes waves?

Answer 30

Seismic waves?

Question 31

What are the different types of seismic waves?

Answer 31

Primary(P-waves), secondary(S-waves) and surface waves

Question 32

What are primary waves?

Answer 32

Longitudinal body waves that travel fast through the Earth. They travel deep under the ground and then bend upwards to reach the surface of the crust. They shake the Earth up and down and refract as they pass through liquid

Question 33

What are secondary waves?

Answer 33

Transverse body waves that travel slightly slower than P-waves through the Earth. They travel deep under the Earth and bend back up to reach the surface of the crust. They shake the Earth back and forth(sideways). They don't travel through liquids.

Question 34

What are surface waves?

Answer 34

They are the slowest seismic waves and cause the most destruction. They travel along the crust near the surface. The closer they are to the surface the more destructive they are. Love and rayliegh waves are surface waves

Question 35

What is the focus?

Answer 35

Where an earthquake starts. It may be 100s of kms into the earth

Question 36

What is the epicentre?

Answer 36

The point directly above the focus.

Question 37

How do we know the structure of the Earth?

Answer 37

After studying the behaviour of different seismic waves, we know that S-waves can't travel through liquids, and using this we have found out that the outer core is liquid

Question 38

What are body waves?

Answer 38

P and S-waves

Question 39

What are love waves?

Answer 39

Surface waves that travel quickly and move side to side?

Question 40

What are Rayleigh waves?

Answer 40

Rolling waves that are very deatructive

Question 41

Why are folds and faults caused?

Answer 41

As the plates move the strata is put under immense pressure all through the plate not just at the boundaries. These forces make pressure in 3 different directions, tension, compression and shear

Question 42

What are folds?

Answer 42

Compression makes them. Syncline folds go down, anticline go up.

Question 43

What is a fault?

Answer 43

If the strata of a rock breaks along a line, it's a fault. Normal faults(one slips under the other) are caused by tension, reverse faults/thrusr faults(one rises) are caused by compression

Question 44

What is graben and horst?

Answer 44

Graben is multiple normal faults, and Horst is multiple reverse faults

Question 45

What are strike slip faults?

Answer 45

Faults caused by strike slip faults(they look kinda like transform boundaries)

Question 46

What are seismic vibrators?

Answer 46

Things that make earthquakes to measure the waves

Question 47

What are deep ocean buoys?

Answer 47

Buoys that measure information on underwater earthquakes and tsunamis