CH. 25 Sec. 3-4

Question 1

What is the boundary that marks a density change between layers?

Answer 1

Discontinuity.

Question 2

How are discontinuities identified?

Answer 2

By studying seismic waves.

Question 3

What are shadow zones?

Answer 3

An area where no seismic waves are recorded.

Question 4

What is another term/name for shadow zones?

Answer 4

Dead zones.

Question 5

Between what degrees do shadow zones fall?

Answer 5

105 to 140 degrees.

Question 6

Is the outer core a solid or a liquid?

Answer 6

It’s a liquid.

Question 7

Is the inner core a solid or a liquid?

Answer 7

It’s a solid because of so much pressure.

Question 8

What makes up the lithosphere?

Answer 8

The crust and uppermost mantle.

Question 9

What is the asthenosphere?

Answer 9

A plastic-like layer which Earth’s plates move.

Question 10

What elements make up the mantle?

Answer 10

Calcium, aluminum, iron, and magneseum.

Question 11

What elements make up the the core?

Answer 11

Iron and nickle.

Question 12

The measure of a fluid’s resistance to flow.

Answer 12

Viscosity

Question 13

The chemical compound silicon dioxide, SiO^2, which is a common ingredient in most magma.

Answer 13

Silica

Question 14

They are small and have heights in the hundreds of meters of range, and have short eruption cycles.

Answer 14

Cinder cone volcanoes

Question 15

They are broad, flat structures composed of layer upon layer of lava flows.

Answer 15

Shield volcanoes

Question 16

Large and steep-sided, often thousands of meters high and tens of kilometers across the base, and composed of layers of both lava and ash.

Answer 16

Composite volcanoes

Question 17

What is molten or liquid rock stored inside the Earth called?

Answer 17

Magma

Question 18

Where is the Ring of Fire located?

Answer 18

Along the Pacific Ocean

Question 19

Melting can occur where?

Answer 19

In the asthenosphere

Question 20

Because the magma is less dense than the surrounding solid rock, it is forced to move which way?

Answer 20

Upward/rise to the surface

Question 21

Rising magma can reach Earth’s surface under what conditions?

Answer 21

If pressure conditions allow and conduits through which it can flow

Question 22

Eruptions are common where plates separate along mid-ocean ridges, continental rifts, and where plates collide along a subduction zones. They are also common where else?

Answer 22

Hot spots

Question 23

Volcanic eruptions occur in which areas?

Answer 23

Where plates separate along a mid-ocean ridge or where plates collide along a subduction zone

Question 24

Most of Earth’s volcanoes that are found along plate boundaries that surround the Pacific Ocean is called the ___________.

Answer 24

Ring of Fire

Question 25

Volcanoes in the northwestern United States and Alaska form along subduction zones inside of what?

Answer 25

The Ring of Fire

Question 26

There are places where volcanic activity occurs on land due to divergence, such as what attraction?

Answer 26

The East African Rift Valley

Question 27

Why do most divergent plate boundary volcanic activity happen and yet are undetected?

Answer 27

Because they occur underwater along mid-ocean ridges.

Question 28

Hot spots are areas of volcanic activity where magma moves toward the surface in large what?

Answer 28

Balloon-like plumes

Question 29

What are two specific locations where volcanic activity occurs due to divergence?

Answer 29

The East African Rift Valley and the Mid-Atlantic Ridge

Question 30

Are hot spots stationary?

Answer 30

Yes

Question 31

What is viscosity?

Answer 31

The resistance to flow

Question 32

If magma has a high viscosity, will it contain more or less silica?

Answer 32

It will contain more

Question 33

What is pyroclastic material?

Answer 33

Any solid material that erupts from a volcano

Question 34

What is the smallest type of pyroclastic material?

Answer 34

Volcanic ash

Question 35

What is the largest pyroclastic material?

Answer 35

Blocks and bombs

Question 36

What are the types of gases that erupt from a volcano?

Answer 36

Water vapour, carbon dioxide, and sulfur dioxide

Question 37

How are volcanoes classified?

Answer 37

By size, shape, and the materials that erupt from it