Questions and Answers
How was the theory of plate tectonics developed?
Plate tectonic theory had its beginnings in 1915 when Alfred Wegener proposed his theory of 'continental drift.'
What is Pangea?
supercontinent
Who came up with the continental drift theory and what does it state?
scientist Alfred Wegener; it states that the continental landmasses were 'drifting' across the Earth.
What empirical evidence supports the theory of continental drift?
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Why was Wegener's theory of continental drift rejected?
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Explain the relationship between the continents, the lithosphere, and the asthenosphere.
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What new evidence led to the theory of plate tectonics?
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Where are the tectonic plates located on Earth?
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What are faults and where are they found?
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Describe the three main types of plate boundary interactions.
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What types of geological events can result from different plate boundary interactions?
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What is accretion?
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What is sea floor spreading?
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What happens during subduction?
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How do the tectonic plate interactions build mountains and cause volcanic eruptions?
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Describe each type of mountain, including type of boundary where they are likely formed.
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Describe each type of volcano.
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Study Notes
Development of Plate Tectonics
- Alfred Wegener proposed the theory of continental drift in 1915.
- Initial findings indicated that continents were drifting across the Earth.
Pangea
- Pangea refers to the supercontinent that existed millions of years ago, when most of Earth's landmasses were joined together.
Continental Drift Theory
- Alfred Wegener formulated the idea that continents were shifting and moving through oceans.
- The theory explained the motion of continental landmasses across the globe.
Empirical Evidence for Continental Drift
- Evidence included the jigsaw-like fit of continents, fossil distribution across continents, alignment of ancient mountain ranges, and paleoclimatic data.
Rejection of Wegener's Theory
- Wegener's theory was largely dismissed due to the lack of a proposed mechanism for continental movement.
Relationship Between Earth's Layers
- Tectonic plates comprise the lithosphere, which includes the crust and upper mantle.
- Lithosphere, about 80 km deep, is supported by the flowing asthenosphere beneath it.
New Evidence for Plate Tectonics
- Fossil records, glacial remains, and matching coastlines provided insights into past continental positions and interactions.
Location of Tectonic Plates
- Tectonic plates reside in the lithosphere of the Earth.
Faults
- Faults are fractures in Earth's crust where tectonic movement has occurred.
- Commonly found in mountain ranges such as the Himalayas and Rocky Mountains.
Types of Plate Boundaries
- Convergent boundaries involve colliding plates, often creating subduction zones.
- Divergent boundaries form where plates move apart.
- Transform boundaries occur as plates slide past one another.
Geological Events from Plate Interactions
- Transform boundaries can lead to earthquakes due to friction.
- Convergent boundaries can result in subduction, causing volcanic activity.
- Divergent boundaries can create underwater mountain ranges like the Mid-Atlantic Ridge.
Accretion
- Accretion is the process in which smaller particles combine to create larger structures.
Sea Floor Spreading
- Sea floor spreading describes how molten material adds new oceanic crust at mid-ocean ridges.
Subduction
- In subduction, one tectonic plate sinks beneath another, melting into magma.
Mountain Building and Volcanic Activity
- Colliding tectonic plates cause the less dense plate to subduct, leading to melting and volcanic formation.
- Volcanic activity is a result of crust melting from subduction.
Types of Mountains
- Fold mountains are formed by the folding of the Earth's crust, often seen in the Himalayas.
- Fault block mountains consist of large rock blocks formed by crustal stresses and faults.
Types of Volcanoes
- Cinder Cone volcanoes are formed from ejected lava blobs and erupt once.
- Stratovolcanoes feature layered lava and ash, commonly found at subduction zones.
- Shield volcanoes are characterized by broad, gentle slopes formed from fluid basaltic lava.
- Calderas are large depressions created by volcanic collapse and magma removal.
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Description
Explore the development of the theory of plate tectonics, including Alfred Wegener's concept of continental drift and the historical context surrounding it. Learn about Pangea, the evidence supporting continental drift, and the relationship between Earth's layers. This quiz will test your understanding of these fundamental geological concepts.
