Unit 2 - Plate Tectonics

Question 1

What observation did early mapmakers make when looking at the continents that made them wonder if they might once have been connected?

Answer 1

looked like puzzle peices

Question 2

Which scientist proposed that all the continents were once connected together?

Answer 2

alfred wegner

Question 3

What did he call his hypothesis?

Answer 3

continental drift

Question 4

Was his hypothesis immediately accepted? Why or why not?

Answer 4

no people needed explanation

Question 5

What did he name his “supercontinent”?

Answer 5

Pangea means all earth

Question 6

How long ago did he think the supercontinent began to break up?

Answer 6

200 million years ago

Question 7

Wegner noticed that several features on adjacent continents matched. Which kinds of features matched? (name at least three)

Answer 7

1) rock formation
2) fossils
3) glacier deposits

Question 8

Before sonar, what did people think the bottom of the ocean looked like?

Answer 8

totally flat

Question 9

What were we able to see with the help of SEABEAM?

Answer 9

mountain canyons

Question 10

The deepest canyon on earth is the ___________________________, and the longest continuous mountain range in the world is the _____________________________.

Answer 10

Mariana trench
mid atlantic

Question 11

Scientists have now identified ________ major tectonic plates that they believe are moving slowly over the earth’s surface.

Answer 11

7

Question 12

These plates seem to move over a semi-solid/semi-liquid layer just beneath the lithosphere. What is this layer called?

Answer 12

antheosphere

Question 13

What kind of forces within the earth seem to be pushing and
pulling on plates, causing them to move?

Answer 13

convention currents

Question 14

What is convection?

Answer 14

transfer of thermal energy by the movement of heated material from one place to another

Question 15

What is the nickname for the area bordering the Pacific Ocean where plates are colliding?

Answer 15

ring of fire

Question 16

How did this area get this name?

Answer 16

from all volcanoes and earthquakes around that area

Question 17

In what direction do plates move at a divergent boundary?
Name an example of a divergent boundary

Answer 17

moving apart
Atlantic ridge or great rift valley on Africa

Question 18

In what direction do plates move at a convergent boundary?
Name an example of a convergent boundary.

Answer 18

toward each other
mt st Helens mt Everest

Question 19

If an oceanic plate pushes under a continental plate, what kind of features often form on the continental plate?

Answer 19

volcano

Question 20

How do plates move at a transform boundary?
Give an example of a transform boundary.

Answer 20

slide past each other
San Andres fault California

Question 21

When an oceanic plate and a continental plate collide, which one is always pushed underneath?
Why is this plate pushed under, rather than over?

What term do geologists use to mean “pushed under”?

Answer 21

the oceanic plate is more dense than continental plate
subducted

Question 22

As the plates at the Mid-Atlantic Ridge move apart
magma fills the space that is created. Where are the
oldest rocks on the seafloor found – close to the ridge
or farther away?

Answer 22

farther away

Question 23

How is earth’s magnetic field “captured” in rocks that are
formed along the MidAtlantic Ridge?

Answer 23

the lava solidifies. iron in it points toward the poles

Question 24

As scientists have studied the rocks along the Ridge, what have they learned about the Earth’s magnetic field?

Answer 24

it has reversed over time

Question 25

Label Earth’s four layers. Next to each label, tell whether the layer is solid or liquid and what type of material (rock or iron & nickel) form the layer.

Answer 25

1. crust- solid rock
2. lower mantle- super heat rock
3. outer core- liquid iron and nickel
4. inner core- solid iron and nickel

Question 26

According to scientists, what causes earth’s magnetic field?

Answer 26

convention currents

Question 27

What happens that makes the field reverse from time to time?

Answer 27

the currents reverse in the outer core which makes magnetic feild reverse

Question 28

Why is the Earth’s inner core solid?

Answer 28

the intense pressure and gravity