 | Term | Definition |
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volcano |
opening in Earth's surface that erupts sulfurous gases, ash, and lava; can form at Earth's plate boundaries, where plates move apart or together, and at hot spots |
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vent |
opening where magma is forced up and flows out onto Earth's surface as lava, forming a volcano |
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crater |
steep-walled depression around a volcano's vent |
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hot spot |
unusually hot area at the boundary between Earth's mantle and core that forms volcanoes when melted rock is forced upward and breaks through the crust; isolated convection current |
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they form on plate boundaries |
How are volcanoes related to Earth's moving plates? |
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acid rain, collapsed buildings and roads, and lung disease |
What effects can pyroclastic flows have on people? |
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it is cooled quickly by seawater |
Why does lava cool rapidly along a mid-ocean ridge? |
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the North American and South American plates slid under the Caribbean plate and magma is being forced upward |
Describe processes that are occurring to cause Soufriere Hills volcano to erupt |
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they would grow larger and more active |
If the Pacific Plate stopped moving, what might happen to the Islands of Hawaii? |
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shield volcano |
broad, gently sloping volcano formed by quiet eruptions of basaltic lava |
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tephra |
bits of rock or solidified lava dropped from the air during an explosive volcanic eruption; ranges in size from volcanic ash to volcanic bombs and blocks |
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cinder cone volcano |
steep-sided, loosely packed volcano formed when tephra falls to the ground |
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composite volcano |
volcano built by alternating explosive and quiet eruptions that produce layers of tephra and lava; found mostly where Earth's plates come together and one plate sinks below the other |
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Silica is the difference. Non silica rich volcanoes are quiet and Silica rich volcanoes are explosive |
Some eruptions are quiet and others are violent. What causes this difference? |
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Basaltic magma is dark and non silica rich. It produces quiet eruptions. Granitic magma is light and silica rich. It produces explosive eruptions. |
Compare and contrast the different types of lava. |
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It can be quiet or violent and it uses both of the eruptions processes. |
How is a composite volcano like a shield and cinder cone volcano? |
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Magma was pushed up through the Pacific Plate at a hot spot. That piece of land moved and another was built. |
Describe how the Hawaiian Islands formed in the Pacific Ocean. |
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it was lava rich in silica because of the explosiveness. |
In 1883, Krakatau in Indonesia erupted. Infer which kind of lava Krakatau erupted- lava rich in silica or lava low in silica. |
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batholith |
largest intrusive igneous rock body that forms when magma being forced upward toward Earth's crust cools slowly and solidifies underground |
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dike |
igneous rock feature formed when magma is squeezed into a vertical crack that cuts across rock layers and hardens underground |
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sill |
igneous rock feature formed when magma is squeezed into a horizontal crack between layers of rock and hardens underground |
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volcanic neck |
solid igneous core of a volcano left behind after the softer cone has been eroded |
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caldera |
large, circular shaped opening formed when the top of a volcano collapses |
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A crater is the depression around a vent and a caldera is when the whole top of a volcano collapses. |
What is the difference between a caldera and a crater? |
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A sill forms when magma is forced into a horizontal crack between rock layers and hardens. A dike forms vertically. |
Describe how a sill forms. How is it different from a dike? |
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A volcanic neck is the solid igneous core of a volcano. It is exposed when the softer cone or outside of a volcano is eroded. |
What is a volcanic neck and how does it form? |
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Magma hardens into rock bodies and they are exposed to the surface by many years of erosion. |
Explain how a batholith forms. |
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They formed originally under the ground. |
Why are the large, granite dome features of Yosemite National Park in California considered to be intrusive volcanic features when they are exposed at the surface? |
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