When magma erupts onto Earth's surface it is called this.
What is lava?
100
A major zone of active volcanoes that encircles the Pacific Ocean is known as this.
What is the Pacific Ring of Fire?
100
Mafic magma has this kind of viscosity.
What is low?
100
This kind of eruption produces pyroclastic material.
What is explosive volcanoes?
100
The funnel-shaped pit at the top of a volcanic vent is called this.
What is a crater?
200
Magma that is rich in magnesium and iron and is commonly dark in color.
What is mafic magma?
200
Many volcanoes occur along these zones when one tectonic plate moves under another.
What is subduction zone?
200
Felsic magma tends to erupt this type of volcanic eruption.
What is explosive?
200
Pyroclastic material that is less than 2 mm in diameter is called this.
What is volcanic ash?
200
These are created when a volcanic cone collapses and leaves a large, basin-shaped depression.
What is a caldera?
300
Magma that is rich in light-colored silicate materials.
What is felsic?
300
The largest amount of magma comes to the surface where plates are moving apart at these. This also creates new lithosphere along the ocean floor.
What are mid-ocean ridges?
300
When lava continues to flow after crust forms, the crust will wrinkle to form this type of volcanic rock.
What is pahoehoe?
300
Volcanic ash that is less than 0.25 mm in diameter is called this.
What is volcanic dust?
300
These volcanic cones are broad at the base and have gently sloping sides. They are a result of quiet eruptions of mafic magma.
What are shield cones?
400
Magma can form if enough pressure is ___________ from the rock, the melting point will decrease and the rock will melt.
What is removed?
400
These are places where volcanism occurs within the interiors of the lithospheric plates.
What are hot spots?
400
When crusted-over lava deforms rapidly or grows too thick to form wrinkles, it will break into jagged chunks forming this.
What is aa?
400
Large pyroclastic particles that are less than 64 mm in diameter are called this, which means "little stones".
What is lapilli?
400
These are made of alternating layers of lava flows and pyroclastic material that come from sometimes quiet eruptions and sometimes explosive eruptions.
What are composite cones or stratovolcanoes?
500
Magma can form when fluids, such as water, are added to the rock. It will __________ melting point.... Or, if the temperature of the rock ___________ ___________ melting point for the minerals the rock is made of.
What are: decrease, rise above?
500
These are what rise to the surface at hot spots, breaking through the crust. They remain stationary, but the plates move, creating volcanic arcs.
What are mantle plumes?
500
Blocky lava has a higher count of this than aa does.
What is silica?
500
Large clots of lava thrown from a volcano that are red-hot and spin through the air, cool and form round or spindle shaped stones are called this.
What are volcanic bombs?
500
These cones have steep sides and come from felsic eruptions.