Plate Tectonics Worksheet Answers Pdf - Fill Online, Printable ... - Free Printable

Let’s go step by step to answer each question on the worksheet. We’ll start with labeling the plate boundary diagrams, then move to the short-answer questions, and finally fill in the vocabulary blanks.

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Part 1: Labeling Plate Boundaries (Diagrams 1–3)

We need to match each diagram to its correct type of plate boundary:

- Diagram 1: Shows two plates moving *away* from each other → This is a divergent boundary.
- Diagram 2: Shows one plate sliding under another → This is a convergent boundary (specifically subduction).
- Diagram 3: Shows two plates sliding past each other horizontally → This is a transform boundary.

So:
1. Divergent boundary
2. Convergent boundary
3. Transform boundary

*(Note: Sometimes textbooks label them as “spreading,” “colliding,” or “sliding” — but standard terms are divergent, convergent, transform.)*

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Part 2: Answering Questions 4a–5

4a. Describe what happens when:

→ Two plates carrying oceanic crust collide:
When two oceanic plates collide, the denser one sinks beneath the other (subducts). This forms deep ocean trenches and can create volcanic island arcs (like Japan or the Aleutian Islands).

→ Two plates carrying continental crust collide:
Continental crust is too light to sink. So when they collide, they crumple and push upward, forming huge mountain ranges (like the Himalayas).

→ A plate carrying oceanic crust collides with a plate carrying continental crust:
The oceanic plate is denser, so it subducts under the continental plate. This creates deep trenches along the coast and volcanoes on the continent (like the Andes Mountains in South America).

5. Explain what force caused the movement of the continents from one supercontinent to their present positions.

The force that moves the continents is called mantle convection. Hot rock deep inside Earth rises toward the surface, cools, and sinks back down. This slow circular motion drags the tectonic plates above it, causing them to move over millions of years.

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Part 3: Building Vocabulary (Questions 6–10)

Fill in the blanks using science terms:

6. A scientific _______ is a well-tested concept that explains a wide range of observations.
→ Theory
*(Example: The theory of plate tectonics explains earthquakes, volcanoes, and mountain building.)*

7. Breaks in Earth’s crust where rocks have slipped past each other are called _______.
→ Faults

8. The lithosphere is broken into separate sections called _______.
→ Tectonic plates (or just “plates”)

9. A(n) _______ is a deep valley on the ocean floor that forms along a divergent boundary.
→ Rift valley (sometimes called mid-ocean ridge rift)

10. The geological theory that states that pieces of Earth’s crust are in constant, slow motion is called _______.
→ Plate tectonics

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Final Answer:

Labeling Diagrams:
1. Divergent boundary
2. Convergent boundary
3. Transform boundary

Question 4a Answers:
- Two oceanic plates collide → One subducts, forming trenches and volcanic islands.
- Two continental plates collide → They buckle and form mountains.
- Oceanic + continental plate collide → Oceanic plate subducts, forming trenches and coastal volcanoes.

Question 5 Answer:
Mantle convection causes the movement of continents.

Vocabulary Blanks:
6. Theory
7. Faults
8. Tectonic plates (or plates)
9. Rift valley
10. Plate tectonics