A _________ is a weak spot in the crust where magma is able to rise to the surface.
What is a volcano?
100
A __________ _____ forms when magma hardens in a volcanoes pipe. The softer rock around it wears of exposing the hard rock.
What is a volcanic neck?
100
________ is a material found in magma that is formed from the elements of oxygen and silica.
What is silica?
100
Beneath a volcano, magma collects in a pocket called a ______ ________.
What is a magma chamber?
100
The ____ ________ is a fault.
What is San Andreas?
200
Thin layers of lava pour out a vent and harden on top of previous layers. Such lava flows gradually build a wide, gently sloping mountain is called _______ ___________.
What is a shield volcano?
200
Magma that forces its way cross rock layers hardens into a ______.
What is a dike?
200
A ________ volcano is a volcano that is sleeping and that, scientists believe, will be active in the future.
What is a dormant volcano?
200
The magma moves through a _____, a long toube in the ground that connects the magma chamber to Earth's surface.
What is a pipe?
200
The ______ ________ is a mountain range.
What is the Sierra Nevada?
300
High silica magma produces ash, cinder, and bombs. These material build up around the vent in a steep, cone-shaped hill or small mountain called ________ ___________.
What is cinder cone?
300
When magma squeezes between horizontal layers of rock, it forms a _______.
What is a sill?
300
A _____ __________ happens when the magma is low in silica. Low-silica magma is thin and runny and flows easily. The gases escape easily and the magma oozes out.
What is a quiet eruptions?
300
Molten rock and gas leave the volcano through an opening called a _____.
What is a vent?
300
_______ ______ or ______ _______ are volcanoes.
What is Mount Shasta or Lassen Peak?
400
Lava flows alternate with explosive eruption of ash, cinder, and bombs. The result is a _________ ____________. They are tall and cone-shaped mountains.
What is compisite volcano?
400
An ___________ forms when magma hardens underground to form igneous rock.
What is an intrusion?
400
An _______ _______ is a dead volcano which will not be active again.
What is an extinct volcano?
400
A ______ ______ is the area covered by open lava as it pours out of a vent.
What is a lava flow?
400
A ______ is a broad bowl-shaped valley.
What is a basin?
500
The huge hole left by the collapse of a volcanic mountain is called ______.
What is a caldera?
500
A __________ is a mass of rck formed when a large body of magma cools inside the crust.
What is a batholith?
500
An __________ _________ happens when the magma is high in silica. High-silica magma is hard and sticky. It buildsup in the pipe and the dissolved gases become trapped. It spews out ash, cinder and, bombs.
What is an explosive eruption?
500
A _______ is a bowl-shaped area that may form at the top of a volcano around the central vent.