Volcanoes

Batholith

A large rock mass that forms when magma cools inside Earths crust. Batholith. A batholith is a huge formation of rock that solidifies deep beneath the Earth's surface.

Caldera

A large, circular hole that forms when the top of a volcano collapses. Caldera. It is a big depression created after a volcanic eruption empties the magma chamber, causing the ground above to collapse.

Cinder cone volcano

A steep, cone-shaped volcano, it is made of ash and cinders. Cinder cone volcano. A cinder cone volcano is formed from the accumulation of volcanic debris around a single vent.

Composite volcano

A tall, cone-shaped volcano, it is made of alternating layers of lava and ash. Composite volcanoes are large, steep volcanoes formed from many layers of volcanic rocks and ash.

Crater

A cup-like shape that forms at the vent of a volcano. Crater. A crater is a bowl-shaped depression formed when a volcano erupts or when a meteorite hits the Earth.

Dike

A slab of volcanic rock formed when magma hardens across layers of rock. Dike. A dike is a sheet of rock that forms when magma cuts through and solidifies in cracks within other rock layers.

Fault-block mountain

Mountains formed as blocks of rock move up or down along faults. Fault-block mountain. These mountains form when Earth's crust cracks, and blocks of rock move up or down along these cracks, creating a rugged landscape.

Geyser

A hot spring that periodically shoots water and steam into the air. Geyser. A geyser is a natural hot spring that erupts with water and steam due to underground heat.

Hot spot

An area where magma melts through the crust above it. Hot spot. A hotspot is a place on Earth where magma consistently breaks through the surface, creating volcanic islands or activity.

Lava

Molten rock that reaches the Earth's surface. Lava. Lava is hot, liquid rock that flows out of a volcano during an eruption.

Magma

Molten rock beneath the Earth's surface. Magma. It's the hot, liquid rock that forms under the Earth's crust and can cause volcanic eruptions when it reaches the surface.

Magma chamber

A large pocket of molten rock under a volcano. Magma chamber. A magma chamber is an underground pool of liquid rock beneath a volcano that can fuel eruptions.

Mountain

A tall landform that rises to a peak. Mountain. A mountain is a large natural elevation of the earth's surface rising abruptly from the surrounding area.

Pyroclastic flow

The fast-moving hot gases, ash, and cinders expelled from a volcano. Pyroclastic flow is a rapid, avalanche-like current of volcanic material that flows down the sides of a volcano during an explosive eruption.

Shield volcano

A wide, gently sloping mountain formed by lava from quiet eruptions. Shield volcano. A shield volcano is a broad, dome-shaped volcano built up by the flow of low-viscosity lava that spreads widely.

Sill

Igneous rock feature formed when magma squeezes between layers of rock. Sill. A sill is a flat layer of rock formed when magma cools and hardens between older layers of earth.

Vent

An opening in the ocean floor where water heated by magma below rises up through cracks. Vent. A vent is a spot where heat from inside the Earth escapes through the ocean floor.

Viscosity

A fluid's resistance to flowing. Viscosity. It is a measure of how thick or sticky a fluid is, determining how easily it moves.

Volcanic neck

Hardened magma in a volcanos pipe. Volcanic neck. A volcanic neck is a column of solidified lava or rock that was once the conduit for magma in a volcano.

Volcano

A mountain through which lava flows to Earths surface. Volcano. A volcano is an opening in the planet's surface that allows hot magma, ash, and gases to escape from below.