algae
Plural Noun

(singular: alga) diverse group of aquatic organisms, the largest of which are seaweeds.

Plural Noun

(singular: bacterium) single-celled organisms found in every ecosystem on Earth.

Noun

large depression resulting from the collapse of the center of a volcano.

debris
Noun

remains of something broken or destroyed; waste, or garbage.

dynamic
Adjective

always changing or in motion.

eruption
Noun

release of material from an opening in the Earth's crust.

fumarole
Noun

vent from which steam is emitted.

Noun

natural hot spring that sometimes erupts with water or steam.

Grand Canyon
Noun

large gorge made by the Colorado River in the U.S. state of Arizona.

Noun

intensely hot region deep within the Earth that rises to just underneath the surface. Some hot spots produce volcanoes.

hot spring
Noun

small flow of water flowing naturally from an underground water source heated by hot or molten rock.

Noun

molten, or partially melted, rock beneath the Earth's surface.

mud pot
Noun

natural spring filled with hot, bubbling mud.

Old Faithful
Noun

geyser in Yellowstone National Park in the U.S. state of Wyoming.

petrify
Verb

to turn to stone.

supervolcano
Noun

volcano capable of ejecting more than 1,000 cubic kilometers (240 cubic miles) of material.

Noun

an opening in the Earth's crust, through which lava, ash, and gases erupt, and also the cone built by eruptions.

Yellowstone National Park
Noun

large national park in the U.S. states of Wyoming, Idaho, and Montana.