The gradual breakdown of rocks in situ by either physical or chemical process is called

Step 1: Analyze the question The key phrases are "gradual breakdown of rocks," "in situ" (meaning in place, without movement), and "physical or chemical process."

Step 2: Explain the concept

• Weathering is the breakdown or decay of rocks in place by physical (mechanical), chemical, or biological processes. No transportation is involved.
• Erosion is the wearing away and removal of rock material by agents such as water, wind, ice, and gravity. It involves movement.
• Denudation is the overall lowering of the land surface. It is a broad term that includes weathering, erosion, and transportation.
• Deposition is the laying down of material that agents of erosion have carried.

Step 3: Work through the options

• A. Erosion: it involves transport, not in situ, so it is wrong.
• B. Denudation: it is too broad and includes removal of material, so it is wrong.
• C. Weathering: it happens in situ through physical or chemical processes, so it is correct.
• D. Deposition: it is the dropping of material, not the breakdown of rock, so it is wrong.

Step 4: Answer The correct answer is C. Weathering.

Exam tip: Whenever you see "in situ" or "in place," think weathering. If the question mentions movement or transport, think erosion. A simple memory line is: Weathering = break down, Erosion = take away, Deposition = drop off.