Plate boundaries

A plate boundary is a meeting place with different traffic rules. Plates can separate, collide, or slide past each other.

Lesson 2 of 33 parts Practice Flashcards

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Divergent boundary and Convergent boundary

Objective: Explain divergent boundary and convergent boundary, distinguish their meanings, and apply them to a described case.

Divergent boundary: Plates move apart and new crust may form as mantle material rises. Convergent boundary: Plates move toward one another, causing subduction or continental collision. Plate boundaries describe relative motion; they are not all identical landscapes. Convergence between oceanic and continental lithosphere differs from collision between two continents. Subduction generates deep earthquakes and can support volcanic arcs, whereas transform motion chiefly accommodates lateral displacement. Some deformation spreads across broad zones. Describe the plate types and movement before inferring the likely features, and recognize that boundaries evolve over geological time. Application: Two plates separate at a mid-ocean ridge. This most directly illustrates divergent boundary. Oceanic crust descends beneath another plate. This most directly illustrates convergent boundary.

Worked examples

Try itOriginal teaching scenario: Two plates separate at a mid-ocean ridge. Which idea from this section does it most directly illustrate?Show answer

Step 1 — Read the observation: Two plates separate at a mid-ocean ridge. Step 2 — Recall the relevant idea: Plates move apart and new crust may form as mantle material rises. Step 3 — Connect the observation to the idea: The scenario is an illustration of divergent boundary. Step 4 — Check the limit: This short scenario illustrates the concept; it does not establish every detail or exclude every other influence in a real situation.

Try itOriginal teaching scenario: Oceanic crust descends beneath another plate. Which idea from this section does it most directly illustrate?Show answer

Step 1 — Read the observation: Oceanic crust descends beneath another plate. Step 2 — Recall the relevant idea: Plates move toward one another, causing subduction or continental collision. Step 3 — Connect the observation to the idea: The scenario is an illustration of convergent boundary. Step 4 — Check the limit: This short scenario illustrates the concept; it does not establish every detail or exclude every other influence in a real situation.

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Divergent boundary and Convergent boundary

Objective: Explain divergent boundary and convergent boundary, distinguish their meanings, and apply them to a described case.

Worked examples

Try itOriginal teaching scenario: Two plates separate at a mid-ocean ridge. Which idea from this section does it most directly illustrate?Show answer

Try itOriginal teaching scenario: Oceanic crust descends beneath another plate. Which idea from this section does it most directly illustrate?Show answer

Transform boundary and Subduction

Objective: Explain transform boundary and subduction, distinguish their meanings, and apply them to a described case.

Transform boundary: Plates slide laterally past one another along a boundary. Subduction: A lithospheric plate descends into the mantle beneath another plate. Plate boundaries describe relative motion; they are not all identical landscapes. Convergence between oceanic and continental lithosphere differs from collision between two continents. Subduction generates deep earthquakes and can support volcanic arcs, whereas transform motion chiefly accommodates lateral displacement. Some deformation spreads across broad zones. Describe the plate types and movement before inferring the likely features, and recognize that boundaries evolve over geological time. Application: Two crustal blocks move sideways along a fault. This most directly illustrates transform boundary. A deep ocean trench marks descending oceanic lithosphere. This most directly illustrates subduction.

Worked examples

Try itOriginal teaching scenario: Two crustal blocks move sideways along a fault. Which idea from this section does it most directly illustrate?Show answer

Step 1 — Read the observation: Two crustal blocks move sideways along a fault. Step 2 — Recall the relevant idea: Plates slide laterally past one another along a boundary. Step 3 — Connect the observation to the idea: The scenario is an illustration of transform boundary. Step 4 — Check the limit: This short scenario illustrates the concept; it does not establish every detail or exclude every other influence in a real situation.

Try itOriginal teaching scenario: A deep ocean trench marks descending oceanic lithosphere. Which idea from this section does it most directly illustrate?Show answer

Step 1 — Read the observation: A deep ocean trench marks descending oceanic lithosphere. Step 2 — Recall the relevant idea: A lithospheric plate descends into the mantle beneath another plate. Step 3 — Connect the observation to the idea: The scenario is an illustration of subduction. Step 4 — Check the limit: This short scenario illustrates the concept; it does not establish every detail or exclude every other influence in a real situation.

Continental collision and Lithosphere

Objective: Explain continental collision and lithosphere, distinguish their meanings, and apply them to a described case.

Continental collision: Two buoyant continental masses converge and thicken crust, commonly building mountains. Lithosphere: The lithosphere is the relatively rigid crust and uppermost mantle divided into plates. Plate boundaries describe relative motion; they are not all identical landscapes. Convergence between oceanic and continental lithosphere differs from collision between two continents. Subduction generates deep earthquakes and can support volcanic arcs, whereas transform motion chiefly accommodates lateral displacement. Some deformation spreads across broad zones. Describe the plate types and movement before inferring the likely features, and recognize that boundaries evolve over geological time. Application: Compressed continental crust forms a high mountain belt. This most directly illustrates continental collision. A moving plate includes both crust and rigid upper mantle. This most directly illustrates lithosphere.

Worked examples

Try itOriginal teaching scenario: Compressed continental crust forms a high mountain belt. Which idea from this section does it most directly illustrate?Show answer

Step 1 — Read the observation: Compressed continental crust forms a high mountain belt. Step 2 — Recall the relevant idea: Two buoyant continental masses converge and thicken crust, commonly building mountains. Step 3 — Connect the observation to the idea: The scenario is an illustration of continental collision. Step 4 — Check the limit: This short scenario illustrates the concept; it does not establish every detail or exclude every other influence in a real situation.

Try itOriginal teaching scenario: A moving plate includes both crust and rigid upper mantle. Which idea from this section does it most directly illustrate?Show answer

Step 1 — Read the observation: A moving plate includes both crust and rigid upper mantle. Step 2 — Recall the relevant idea: The lithosphere is the relatively rigid crust and uppermost mantle divided into plates. Step 3 — Connect the observation to the idea: The scenario is an illustration of lithosphere. Step 4 — Check the limit: This short scenario illustrates the concept; it does not establish every detail or exclude every other influence in a real situation.

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