Questions For Test Flashcards
What three things combine to make magma?
Rock-forming substances, gases, and water
Define volcano
A mountain that forms in Earth’s crust when molten material reaches the surface
What is lava
Magma that has already reached earths surface
Define magma
Hasn’t reached earths surface yet. Made of rock-forming substances, gases, and water
What is the ring of fire?
The many volcanoes that rim the Pacific Ocean.
What is a hotspot?
An area that material from deep within earth rise through the crust and melts to form magma.
Define magma chamber
An area beneath a volcano where magma collects
Define pipe
A long tube that connects the magma chamber to Earth’s surface
Define vent
An opening in a volcano through which molten rock and magma escape.
Define lava flow
The spread of lava as it pours out of the vent
Define crater
A bowl-shaped area that may form at the top of a volcano around the central vent
Define silica
A compound made of silicon and oxygen.
The amount of silica found in the magma will help determine which type of eruption will occur.
Define quiet eruption
Quiet eruptions occur when the magma is hot or low in silica.
Hot, low-silica magma is thin and runny and flows easily.
Define explosive eruption
Occur when the magma is high in silica.
This type of magma is thick and plugs up the volcano’s pipe.
Define dormant volcano
A volcano that is not presently active but scientists expect it to become active in the future.
Define extinct volcano
A volcano that is unlikely to ever erupt again.
Define caldera
A huge hole left when a volcano collapses.
Often a lake will form in the hole
They form when large eruptions empty into the magma chamber and main vent.
Nothing is left to support the mountain top and it collapses inward.
What does a caldera form
Nothing is left to support the mountain top and it collapses inward Often a lake will form in the hole
They form when large eruptions empty into the magma chamber and main vent
Define a Cinder cone volcano
A steep, cone-shaped hill or small mountain made of volcanic ash, cinders, and bombs
How does a Cinder cone volcano form
Ash, cinders and bombs build up around the central vent when the volcano erupts explosively which pile up around the volcanoes opening adding layers called cinders
Describe a shield volcano
The lava builds a wide, gently sloping volcano.
How does a shield volcano form?
Forms when lava flows out of a volcano in a series of quiet eruptions
Describe a composite volcano
Tall mountains
Mount St. Helens is a composite volcano
How does a composite volcano form
Form when the volcano alternates between explosive and quiet eruptions.
A layer of lava forms, then a layer of ash, cinders and bombs.
These are also called stratovolcanoes.
Mount St. Helens is a composite volcanoes.
