science test volcanoes

What is a cone-shaped mountain formed from ash, cinders and bombs?

Shield volcanoes

Volcanoes can form along diverging plate boundaries where oceanic crust returns to the mantle.

True

Describe how volcanoes form along the mid-ocean ridges?

Volcanoes form along mid-ocean ridges becuase of rift valleys.

What is a gently sloping mountain formed by repeated lava flows?

cinder cone

What is the Ring of Fire?

A major belt of volcanoes that rims the Pacific Ocean.

What is a volcano?

A weak spot in the crust where molten material, or magma, comes to the surface.

Where do most volcanoes form?

Along the rim of the Pacific Ocean.

What are hot spots?

An area where material from deep within the mantle rises and then melts, forming magma.

Where does a crater form?

At the top of a volcano around the central vent.

What is a mass of rock formed when a large body of magma cools inside the crust?

Batholith

Why are volcanic soils fertile?

Because of the lava, ash and cinders that erupt from a volcano potassium and folferus.

The pipe of a volcano is a horizontal crack in the crust.

False

When frozen water melts, it is undergoing a physical change.

False

When magma reaches the surface, it is called _____________.

Lava

What is a mountain formed by lava flows alternating with explosive eruptions?

Lava plateau

What is a molten mixture of rock-forming substances, gases and water from the mantle referred to as?

Magma

What is made of elements and compounds? Among them silica

Magma

Explain why ash, cinders and bombs are produced only in explosive eruptions, not in quiet eruptions.

The lava will be ejected focrcely and the lava is cooked and hardens quickly to form different sized pieces.

What is geothermal energy? How is it used?

The water is heated by magma underground. Then the water is piped into buildings as a heat source and the steam is piped into turbines to create electricity.

Many volcanoes form near converging plate boundaries where oceanic crust returns to the mantle.

True

Some types of volcanic activity do not involve the eruption of lava.

True.

What depends on silica content and temperature?

Viscosity

What is cool, slow-moving lava called?

aa

What stage of a volcano is erupting or showing signs that it soon will erupt?

activity

What type of lava has particles ranging from the size of a baseball to the size of a car?

bombs

What is a hole left by the collapse of a volcanic mountain?

caldera

When a substance burns, this is an example of a __________ property

chemical

What type of lava has pebble-sized particles?

cinders

What is a high, level area formed by repeated lava flows?

composite volcano

What is the bowl-shaped area tha tforms around a volcano's central vent?

crater

What is the slab that forms when magma forces itself across rock layers?

dike

What stage of a volcano is no longer active but may become active again?

dormant

A substance that cannot be broken down into other substances is called _______________________.

element

What stage of a volcano is unlikely to erupt ever again?

extinct

The _______________ the viscosity, the more easily a liquid flows.

faster

What is a fountain of water and steam that erupts from the ground referred to as?

geyser

What is the build up of layers of thin, runny lava that flow over a wide area before they cool and harden?

lava plateau

Liquid magma flows upward through the crust because it is ____ dense than the solid material around it.

less

What is hot, fast-moving lava called?

pahoehoe

When an explosive eruption hurls ash, cinders, bombs, and gases out of a volcano it is called a ___________ _______.

pyroclastic flow

What rock forms from light-colored lava?

rhyolite

What is the material found in magma that is formed from oxygen and silicon?

silica

What is the slab that forms when magma squeezes between layers of rock?

sill

The greater the viscosity, the _________________ a liquid flows.

slower

What is a lava flow?

the area covered by lava as it pours out of a vent.

What factors determine the force of a volcanic eruption?

the pressure inside of the Earth's crust

What type of lava has fine rocky particles as small as a grain of sand?

volcanic ash

What forms when magma hardens in a volcano's pipe and is later exposed?

volcanic neck

What type of rocks does low-silica magma form?

Basalt

List 3 physical properties of magma:

1. Viscosity 2. Temperature 3. silica content

What forms when the top of a volcanic mountain collapses?

A caldera forms