Continental Drift and Plate Tectonics
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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?

<p>Fit of the continents, distribution of ancient fossils, rocks, mountain ranges, and locations of ancient climatic zones.</p> Signup and view all the answers

Why was Wegener's theory of continental drift rejected?

<p>Because he suggested no mechanism for moving the continents.</p> Signup and view all the answers

Explain the relationship between the continents, the lithosphere, and the asthenosphere.

<p>The tectonic plates are made up of Earth's crust and the upper part of the mantle, called the lithosphere, and the flowing asthenosphere carries the lithosphere, including the continents.</p> Signup and view all the answers

What new evidence led to the theory of plate tectonics?

<p>Evidence from fossils, glaciers, and complementary coastlines.</p> Signup and view all the answers

Where are the tectonic plates located on Earth?

<p>In the lithosphere.</p> Signup and view all the answers

What are faults and where are they found?

<p>Faults are fractures in Earth's crust where movement has occurred; they are found in regions like the Himalayas and the Rocky Mountains.</p> Signup and view all the answers

Describe the three main types of plate boundary interactions.

<p>Convergent boundaries involve colliding plates; divergent boundaries involve plates moving apart; transform boundaries involve plates sliding past each other.</p> Signup and view all the answers

What types of geological events can result from different plate boundary interactions?

<p>Transform boundaries can cause earthquakes; convergent boundaries often result in one plate sliding below the other; divergent boundaries can create submarine mountain ranges.</p> Signup and view all the answers

What is accretion?

<p>The coming together of smaller pieces of matter to form larger ones.</p> Signup and view all the answers

What is sea floor spreading?

<p>The process by which molten material adds new oceanic crust to the ocean floor.</p> Signup and view all the answers

What happens during subduction?

<p>One plate sinks down under another and is melted into magma.</p> Signup and view all the answers

How do the tectonic plate interactions build mountains and cause volcanic eruptions?

<p>When plates collide, the less dense plate overrides the denser plate, leading to subduction and the formation of volcanoes as old crust melts.</p> Signup and view all the answers

Describe each type of mountain, including type of boundary where they are likely formed.

<p>Fold mountains are formed by folding of Earth's crust; fault-block mountains are created by tectonic stresses; each has distinct characteristics based on their formation processes.</p> Signup and view all the answers

Describe each type of volcano.

<p>Cinder Cone: built from blobs of lava ejected from a single vent; Stratovolcano: built of layers of lava and ash; Shield Volcano: gentle slopes from fluid lava; Calderas: depressions created by volcanic collapse.</p> Signup and view all the answers

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.

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