Weathering, Erosion & Deposition — Drills · Grade 9 Science

Chapter: Rocks, Landscapes & Water

What these drills covers

By the end of Weathering, Erosion & Deposition you should be able to:

8 questions, multiple choice, numeric and written answer, each with a worked explanation.

Vocabulary used: weathering, erosion, deposition, sediment.

Problem 1

Weathering differs from erosion because weathering
  1. moves material
  2. breaks material down in place
  3. deposits material
  4. only happens in water
Answer and explanation

breaks material down in place

Weathering breaks rock down where it sits; erosion transports the pieces.

Problem 2

Water freezing in a crack and widening it is
  1. chemical weathering
  2. physical weathering
  3. erosion
  4. deposition
Answer and explanation

physical weathering

Ice expands and prises the rock apart without changing its chemistry.

Problem 3

Acidic rainwater dissolving limestone is
  1. physical weathering
  2. chemical weathering
  3. deposition
  4. compaction
Answer and explanation

chemical weathering

A chemical reaction changes the minerals into soluble products.

Problem 4

Sediment is deposited when the transporting agent
  1. speeds up
  2. slows down
  3. freezes
  4. evaporates only
Answer and explanation

slows down

Slower water or wind can no longer carry the particles, so the largest settle first.

Problem 5

Which would weather fastest in a warm, wet climate?
  1. Granite
  2. Limestone
  3. Quartzite
  4. Basalt glass
Answer and explanation

Limestone

Limestone dissolves readily in slightly acidic water, producing caves and sinkholes.

Problem 6

A cliff retreats 0.4 m per year. How many metres does it retreat in 25 years?
Answer and explanation

10 m

0.4 × 25 = 10 m.

Problem 7

Explain why breaking a rock into smaller pieces speeds up chemical weathering.
Answer and explanation

Chemical weathering acts on exposed surfaces, and breaking a rock into pieces greatly increases the total surface area while the volume stays the same. More surface is in contact with water and air, so reactions proceed faster. This is why physical and chemical weathering reinforce each other rather than acting independently.

Response criteria

  • State a scientifically accurate conclusion.
  • Show the data, mechanism, or calculation that supports it.
  • Include units, conditions, or limits where relevant.

Problem 8

Describe how a river sorts sediment along its course and why.
Answer and explanation

Fast-flowing upper reaches carry everything, including boulders. As the gradient lessens and the water slows, the largest particles can no longer be carried and settle first, then progressively smaller ones, leaving fine silt and clay to reach the mouth or the sea. The sorting therefore records the energy of the water at each point, which is why grain size in a deposit indicates the conditions when it formed.

Response criteria

  • State a scientifically accurate conclusion.
  • Show the data, mechanism, or calculation that supports it.
  • Include units, conditions, or limits where relevant.

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