Questions and Answers
What is the difference between magma and lava?
Magma refers to molten rock below Earth's surface, while lava refers to molten rock at the surface.
List the three factors that determine the nature of a volcanic eruption. What role does each play?
- Composition of magma, 2) Temperature of magma, 3) Quantity of dissolved gases.
Describe pahoehoe and aa lava.
Pahoehoe lava has a smooth or ropy appearance, while aa lava has a sharp and jagged surface.
List the main gases released during a volcanic eruption. What role do gases play in volcanic eruptions?
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Compare a volcanic crater to a caldera.
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Compare and contrast the three main types of volcanoes.
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Name a prominent example of each of the three types of volcanoes.
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What is Shiprock, New Mexico and how did it form?
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What is the Ring of Fire?
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What type of plate boundary is associated with the Ring of Fire?
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Study Notes
Volcanic Terminology
- Magma vs. Lava: Magma is molten rock beneath Earth’s surface; lava refers to molten rock that reaches the surface.
Factors Influencing Eruptions
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Three Key Factors:
- Composition of magma affects its viscosity.
- Temperature influences magma's fluidity.
- Quantity of dissolved gases determines eruption force and nature.
Types of Lava
- Pahoehoe Lava: Characterized by a smooth or ropy appearance; results from fluid basaltic lava.
- Aa Lava: Has a jagged, sharp surface; forms from more viscous magma.
Gases Released in Eruptions
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Major Volcanic Gases:
- Water vapor (70%)
- Carbon dioxide (15%)
- Nitrogen (5%)
- Sulfur compounds (5%)
- Trace amounts of chlorine, hydrogen, and argon.
Volcanic Features
- Volcanic Crater: Smaller depression at the vent for erupting materials formed through erosion by incoming magma.
- Caldera: Large depression from the collapse of a volcano after a massive eruption, resulting from magma chamber evacuation.
Types of Volcanoes
- Shield Volcanoes: Large, gently sloping domes associated with quiet eruptions and mostly fluid basaltic lava.
- Cinder Cones: Steep-sided, composed of pyroclastic material; the smallest volcano type.
- Composite Cones: Formed by alternating layers of lava and pyroclastic debris; steeper than shield volcanoes, known for violent eruptions.
Examples of Volcanoes
- Shield Volcano: Mauna Loa, Hawaii.
- Cinder Cone: Paricutin, Mexico, with smaller cones in Arizona.
- Composite Cone: Mt. Fuji, Japan; Mt. Shasta, California; volcanoes of the Cascade Range.
Shiprock Formation
- Shiprock, NM: Landmark formed from the erosion of surrounding sedimentary rock, revealing the hard igneous rock of a former volcano's plumbing system.
The Ring of Fire
- Definition: Extensive arc of volcanic and seismic activity, from New Zealand to North and South America, comprised of over 75% of the world’s active and dormant volcanoes.
- Tectonic Features: Located primarily at the borders where the Pacific Plate meets other major tectonic plates.
Plate Boundaries and the Ring of Fire
- Subduction Zones: The Ring of Fire’s volcanoes are primarily associated with subduction zones, where tectonic plates move beneath each other, leading to volcanic activity.
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Description
Test your knowledge with these flashcards on Chapter 7 of Earth Science. This chapter covers key concepts such as the differences between magma and lava, as well as the factors that influence volcanic eruptions. Perfect for review and reinforcement of essential geological topics!
