Volcanoes Flashcards
What is a volcano?
Any natural opening in the Earth’s crust, called a fissure, where molten rock,ash,gases and steam come out.
Why do volcanoes look like mountains?
Volcanoes look like mountains, but they are really flat land that is pushed upward because of the pressure below the earth. The pressure comes from hot magma and gases that build up below the earth’s surface and that work up to the surface through cracks in the earth’s plates. As it is forced up to the surface, the gases and magma push the earth up with it forming the mountain shape.
What is beneath the crust?
Magma
What is molten rock called when it reaches the surface?
Lava
What is a volcano?
A landform produced by the accumulations of erupted material around a vent or opening in the surface of the earth.
Where do volcanic mountains occur?
They occur along a plate boundary where an oceanic plate subsidy’s beneath a continental or oceanic, or on land in association with rift valleys.
What are rift valleys?
They are areas where continental plates stretch and thin over a long period of time.
What are hotspots?
Hot spots are places within the mantle where rocks melt to generate magma
How are eruptions from oceanic hot spot volcanoes?
“Runny” and less viscous lava.
Volcanoes can erupt lava flows on the ground or throw material into the air. Rock fragments thrown into the air include ________ and ____________(more than 1 word).
Ash
Larger rock fragments
How do ash clouds rise?(5)
- Upward force
- Volcanic Eruption
- Pressure release
- Density differences between ash and air
- Convection
What are fissure eruptions?
They occur when molten rock flows through cracks in the earth’s and flood the surrounding landscape.
