Important Terms and Definitions


A caldera is a basin-shaped volcanic depression that is at least one mile in diameter.


Long Valley Caldera
A volcanic depression located in eastern California that is 20 miles by 10 miles in size. Mammoth Mountain sits on the Long Valley Caldera. To see pictures of the Long Valley Caldera click here.
relating to earthquakes.
Mono-Inyo Craters Volcanic Chain
A large chain of volcanos spanning from North Mono Lake to Mammoth Mountain. To see pictures of the Mono-Inyo Craters Volcanic Chain click here.


Pertaining to the study of the formation, movement and activities of the earth's crust.
Pyroclastic Flow
A flow of lava from the side of a volcano. The lava in a Pyroclastic flow is made of hot gases, fragments of rock, crystals, ash, and glass. It moves very quickly (50-100 miles an hour).