Plate Techtonics

Front 1

A. The _________________ hypothesis---continents have moved slowly to their current location.
1.All continents were once connected as one large land mass now called _______.
2. The land mass broke apart, and the __________ drifted to their present positions.
3. Evidence for continental drift:
a. ___________ fit of the continents
b. Similar _______ have been found on different continents.
c. Remains of warm-weather plants in _____ areas and glacialdepostits in ________ areas suggests that continents have moved.
d. Similar ____ structures are found on different continents.

Back 1

*continental drift
*Pangaea
*continents
*puzzle-like
*fossils
*artic
*tropical
*rock

Front 2

B. At first, continental drift was not accepted because no one could explain ___ or ___ continents had moved.

Back 2

*how
*why

Front 3

A. Using _____ waves, scientists discovered a system of underwater mountain ranges called the mid-ocean ridges in many oceans.

Back 3

sound

Front 4

B. In the 1960s, Harry Hess suggested the theory of __________________ to explain the ridges.
1. Hot, less dense material below Earth's _____ rises upward to the surface of mid-ocean ridges.
2.Then, it flows sideways, carrying the _______ away from the ridge.
3. As the seafloor spreads apart, _____ moves up and flows from the cracks and forms new seafloor.

Back 4

*seafloor spreading
*crust
*seafloor
*magma

Front 5

C. Evidence for Seafloor Spreading:
1. ________ rocks are located at mid-ocean ridges.
2.Reversals of Earth's ________ field are recorded by rocks in strips parrallel to ocean ridges.

Back 5

*Youngest
*magnetic

Front 6

A. Plate Movements
1. Earth's _____ and upper mantle are broken into sections.
2. The sections, called ______, move on a plasticlike layer of the mantle.
3. The plates and upper mantle form the ___________
4. The plasticlike layer below the lithosphere is called the _____________

Back 6

*crust
*plates
*lithosphere
*asthenosphere

Front 7

B. Plate Boundaries
1. Plates moving _____--divergent boundaries
2. Plates moving ________--convergent boundaries
a. Denser plate sinks under less _____ plates.
b. Newly formed hot _____ forced upward forms volcanic mountains.
3. Plates collide
a. Plates crumple up to form ________ ranges.
b. ___________ are common.
4. Plates slide past--called _________ boundaries; sudden movement can cause earthquakes.

Back 7

*apart
*together
*dense
*magma
*mountain
*earthquakes
*force

Front 8

C. Convection inside Earth--the cycle of heating, rising, cooling, and sinking of material inside Earth is thought to be the _____ behind plate techtonics.

Back 8

force

Front 9

D. Features caused by Plate Techtonics
1. Faults and ____ Valleys
2. Mountains and _________
3. Strike-slip faults--cause of ___________

Back 9

*Rift
*volcanoes
*earthquakes

Front 10

Testing for plate techtonics--scientists can measure _______________ as little as 1 cm per year.

Back 10

exact movements

Front 11

plasticlike layer of Earth's surface below the lithosphere

Back 11

asthenosphere

Front 12

cycle of heating, rising, cooling, and sinking

Back 12

Convection Current

Front 13

theory that states that Earth's crust and upper mantle are broken into sections, which move around on a special layer of the mantle

Back 13

Plate Techtonics

Front 14

area where an oceanic plate goes down into the mantle

Back 14

subduction zone

Front 15

plate boundary that occurs when two plates slide past one another

Back 15

Transform Boundary

Front 16

place where two plates move together

Back 16

Convergent Boundary

Front 17

rigid layer of Earth's surface made up of the crust and part of the upper mantle

Back 17

lithosphere

Front 18

sensing device that detects magnetic fields, helping to confirm seaflorr spreading

Back 18

magnetometer

Front 19

one large landmass hypothesized to have broken apart 200 million years ago into continents

Back 19

Pangaea

Front 20

hypothesis that continents have moved slowly to their currents locations

Back 20

continental drift

Front 21

boundary between two plates that are moving apart

Back 21

divergent boundary

Front 22

sections of Earth's crust and upper mantle

Back 22

Plates

Front 23

largest layer of Earth's surface, composed mostly of silicon, oxygen, magnesium, and iron

Back 23

Mantle

Front 24

outermost layer of Earth's surface

Back 24

crust

Front 25

where rocks on opposite sides of a fault move in opposite directions or in the same direction at different rates

Back 25

strike-slip fault

Front 26

The Seafloor Spreading Theory was proposed by __________

Back 26

Harry Hess.

Front 27

As Earth's plates move apart at some boundaries, they collide at others forming _________,_________, and ____________.

Back 27

*mountains
*volcanoes
*ocean basins

Front 28

The youngest rocks in the ocean floor are located at the mid-ocean ______.

Back 28

ridges

Front 29

The results of plate movement can be seen at ____________ and ________________.

Back 29

*rift valleys
*plate boundaries

Front 30

The _________ are forming where the Indo-Austrailian plate collides into the Eurasian plate.

Back 30

Himalayas

Front 31

The presence of the same _______ and _____ on several continents supports the idea of continental drift.

Back 31

*fossils
*rocks

Front 32

Continental Drift occurs because of __________________.

Back 32

Seafloor Spreading

Front 33

The cycle of heating, rising, cooling, and sinking is called a __________________.

Back 33

convection current

Front 34

Oceanic plates are pushed down into the upper mantle in ________________.

Back 34

subduction zones

Front 35

The hypothesis that continents have moved slowly to their current locations is called _______________.

Back 35

continental drift

Front 36

Plates move apart at _________ boundaries.

Back 36

Divergent

Front 37

Ocean floors are ____________ continental rocks.

Back 37

younger than

Front 38

The alignment of iron bearing minerals in rocks when they formed reflects the fact that Earth's ______________ has reversed itself several times in its past.

Back 38

magnetic field

Front 39

The lack of an explanationfor continental drift prevented many scientists from believing a single supercontinent called _______ once existed.

Back 39

Pangaea

Front 40

Scientists aboard the Glomar Challenger added to the evidence for the theory of seafloor spreading by providing ________________________________________.

Back 40

samples of rock from different locations

Front 41

Where plates slide past one another, ___________ occur.

Back 41

earthquakes

Front 42

The places between plates moving together are called ____________________.

Back 42

convergent boundaries

Front 43

Seafloor Spreading occurs because ________________________________________________________________________________.

Back 43

hot, less dense material below Earth's crust is forced upward toward the surface

Front 44

Studying the ocean floor, scientists found rocks showing magnetic ________.

Back 44

reversal

Front 45

The theory that describes Earth's crust and upper mantle as being broken into sections is called__________.

Back 45

plate tech tonics

Front 46

The theory of _______was shown to be correct by age evidence and magnetic clues.

Back 46

seafloor spreading

Front 47

_______, occuring in the mantle, are thought to be the force behind plate tectonics.

Back 47

Connection current

Front 48

Earth's plasticlike layer is the __________.

Back 48

asthenosphere

Front 49

Earth's _______ move around on a special layer of the mantle.

Back 49

plates

Front 50

The main lines of evidence for ______ ______ are fossil, rock, and climate clues, and the theory of seafloor spreading.

Back 50

continental drift

Front 51

The rigid part of the plates of the _______ are made of oceanic crust and upper mantle.

Back 51

lithosphere

Front 52

The name _______means "all land."

Back 52

pangaea

Front 53

What is the difference between a convergent and a divergent plate boundary?

Back 53

Convergent plates move together; divergent plates move apart.

Front 54

What happens to warmer material in a convection current?

Back 54

Warmer material rises.

Front 55

What observation led Albert Wegner to develop the hypothesis of continental drift?

Back 55

The edges of some continents looked as though they would fit together.

Front 56

What part of Earth's surface is about 100 km thick?

Back 56

Lithospere

Front 57

How were Andes mountain range, the Himalayas, and the islands of Japan formed alike?

Back 57

All were formed at convergent Boundaries.

Front 58

How were the Andes Mountain Range, the Himalayas, and the islands of Japan formed differently?

Back 58

The Andes were formed at the convergent boundary of an ocean plate and a continental plate; the islands of Japan were formed where two oceanic plates collided; the Himalayas formed when two continental plates collided.

Front 59

What causes new material to form at a mid-ocean ridge on the ocean floor?

Back 59

Hot, less dense material below Earth's crust is forced upward at the mid-ocean ridges. Then it turns and flows sideways, carrying the seafloor away from the ridge in both directions.

Front 60

Why are there few volcanoes in the Himalayas?

Back 60

The plates that collide to form the Himalayas crumple, but no subductions take place. Volcanoes occur above subduction zones.

Front 61

Glacial deposits often form at a high latitude near the poles. Explain why glacial deposits have been found in Africa.

Back 61

When the continents were connected, they were covered with ice near Earth's south pole.

Front 62

Why would the fossil of an ocean fish found on two different continents NOT be good evidence of continental drift?

Back 62

It's possible for ocean fish to swim all over the world, so they could have reached all continents.

Front 63

Explain how research from the Glomar Challenger helped scientists support the theory of seafloor spreading.

Back 63

The Glomar Challenger had a drilling rig that allowed scientists to obtain rock samples from the seafloor. They discovered that the youngest rocks are located at mid-ocean ridges. The rocks became increasingly older in samples obtained from the ridges, adding to the evidence for seafloor spreading.

Front 64

Since new crust is constantly being added, why does Earth's surface not keep expanding?

Back 64

As new crust is added in one place, it disappears below the surface in another. The disappearance of crust can occur when seafloor cools, becomes denser, and sinks. This occurs when two plates meet at a convergent boundary.

Front 65

Compare and contrast divergent, convergent, and transform plate boundaries.

Back 65

All are boundaries of techtonic plates, but they behave in different ways. At divergent boundaries, plates move away from each other. Convergent boundaries occur when 2 plates move together. Then 1 of 3 things will happen; one plate may sink under the other; one plate may bend and slide under the other; or both may crumple. A transform boundary occurs when two plates slide past each other.

Front 66

Describe how convection currents might be the cause of plate techtonics.

Back 66

Scientists hypothesize that the cycle of heating, rising, cooling, and sinking of the hot, plasticlike rock in the asthenosphere provides the energy to move plates in the lithosphere.

Front 67

Whay are new ideas often rejected, and what is needed before new ideas should be accepted.

Back 67

Some new ideas are so different from people's thinking that people cannot accept them. New ideas should be backed by some evidence before they are accepted.