A volcano that is currently erupting or has recently erupted (within the past 300 years)

Tiny particles of pulverized rock created and ejected during an explosive volcanic eruption.

The top rock material in a pillar that shields the underlying layers of sediment

 A deep valley with steep, rocky sides.

A steep conical volcano that is built up of bits of lava and small fragments of solid rock

A volcanic mountain built up be accumulations of lava and ash

A long wave that deposits material after it breaks, building up a beach.

Sheets of glacial ice that cover a large expanse of land, such as Greenland or Antarctica.

A sand dune that forms along ocean beaches.

The depression, or opening, at the top of a volcano that forms when a volcano erupts or a volcanic vent collapses.

 A small stream.

 An area of land where relatively large rocks have been carried and scattered by ice, water, or volcanic eruptions.

A fan-shaped deposit of sand, silt, and soil that forms where the mouth of a river flows into a lake, bay, or ocean.

The process in which water, wind, or ice drops sediment in new locations.

The change of arable land into desert due to natural or human-caused factors.

A high wave with a strong backwash that erodes material after it breaks, causing the beach to deteriorate.

 A volcano that is not currently erupting, but that geologists believe may erupt again.

A windstorm that carries clouds of dust and sediment.

 Shaking or trembling of the earth’s crust due to volcanic forces or the shifting of tectonic plates deep underground.

The movement of sediment from one place to another on Earth’s surface.

A volcano that is not currently erupting and is unlikely to ever erupt again.

A crack along the flank of a volcano where lava erupts.

 A sudden rush of water down a slope or narrow gully caused by heavy rainfall.

A large amount of water that inundates areas that are normally dry.

A flat area bordering a river that is formed by the deposition of sediment that was carried by the river.

A resistive force between two objects rubbing together.

A large rock moved and dropped in a new location by a glacier.

A mixture of rock, gravel, clay, and silt dropped by a glacier as it melts.

 A large, long-lasting mass of moving ice and snow.

The force of attraction that exists between all objects in the universe with mass.

A body of salt water connected to an ocean and partially surrounded by land

The streams from which a river originates.

A landform that rises higher than the surrounding land, but is not as tall as a mountain.

A strangely-shaped rock formation, usually sculpted by water erosion.

Violent tropical cyclone storms with torrential rains and wind speeds over 117 kilometers (73 miles) per hour.

The force of water that can crumble and split rock along a shoreline.

An area of land that is completely surrounded by water.

A pond formed by a retreating glacier.

The Indonesian word for mudflow. A rapidly flowing mixture of rock debris and water that originates on the slope of a volcano.

An inland body of standing or slow moving water completely surrounded by land.

A physical form or feature on Earth’s surface having a characteristic recognizable shape and produced by natural causes.

A mass of rocks, soil, and debris that suddenly slides down a steep slope.

Magma that comes out of a volcano onto the earth’s surface.

 A stream of magma that flows onto the earth’s surface.

The material formed by melting rock inside the earth.

A pile of unsorted rock and debris dropped by a glacier as it melts.

A part of Earth’s surface that is higher than the surrounding lowlands and forms a peak.

Where a river meets a lake, valley, or ocean.

A mass of water, rocks, soils, and debris that suddenly slides down a steep slope.

A rock formation caused by wind erosion that has a narrow base and wide top.

The largest bodies of salt water on Earth’s surface.

A large land area surrounded by water on three sides.

Physical forces, such as water and wind, that break down rock.

 A broad, flat area of land that stretches over great distances.

A broad, flat, elevated area of land that stretches over great distances and is typically separated from the surrounding land by steep slopes.

A standing or slow moving body of water completely surrounded by land.

An avalanche of hot ash, rock fragments, and gas that rushes down the side of a volcano during an eruption.

A body of flowing water that empties into an ocean, lake, or other body of water.

A tall column of rock that has been shaped by a combination of wind and water, weathering and erosion.

A hill or ridge of loose sand formed by wind deposition.

Wave-like patterns that form on the surface of sand.

A ridge of sand formed in a river or along the shore caused by the action of moving water.

Materials, including rock, sand, gravel, silt, and soil, that have been carried along and deposited by water, wind, or ice.

A volcano with a broad, rounded shape.

Bits of rock smaller than sand, but bigger than clay. Silt feels gritty when rubbed between your fingers.

The angle of the earth’s surface relative to horizontal.

A natural, underground water source that flows to Earth’s surface.

The increase in river flow that results from rapid melting of snow in the spring.

A body of flowing water that is smaller than a river and larger than a creek.

The texture, hardness, and quality of the ground surface.

Large segments of the uppermost layers of Earth’s surface.

Surface soil usually composed of both organic and rock material.

A violent spiraling column of air that is generated by a cumulonimbus storm cloud.

Any creek, stream, or river that flows into a larger creek, stream, or river.

A huge wave of ocean water that hits land and is caused by an earthquake or volcanic eruption under the ocean.

The low land that lies between mountains or hills.

An opening in the earth’s crust that releases molten rock and volcanic gases onto the earth’s surface or into the atmosphere.

Water that flows over a drop-off of several feet to hundreds of feet, forming a cascade or sheet of water.

 A raised ridge of water that appears to move across the surface of a body of water.

The breaking down of rocks into smaller pieces at or near the earth’s surface.

Turbulent, foaming, and bubbling water seen in fast-flowing streams and rivers.

Air that is in motion over the surface of the earth.

The measurable rate at which wind travels, generally measured in kilometers or miles per hour.