In geomorphology, what do we call a deep valley between cliffs often carved into the landscape by a river?

Introduction / Context:
Rivers are powerful agents of erosion and can carve dramatic landforms into the Earth surface over long periods of time. One of the most spectacular river created features in world geography is a very deep and steep sided valley, often with high cliffs on both sides and a river flowing at the bottom. Famous examples such as the Grand Canyon appear frequently in textbooks, documentaries, and examination questions. Knowing the correct geographic term for this deep valley type is important for students of physical geography and geomorphology.

Given Data / Assumptions:
- The landform is a deep valley between cliffs.
- It is often carved into the landscape by a river over a long time.
- The options list common landform names such as canyon, plateau, plain, delta, and basin.
- We assume standard definitions of these landforms as used in school and competitive exam material.

Concept / Approach:
When a river flows over resistant rock and the land is uplifted or gradients are steep, vertical erosion can dominate. Over millions of years, the river incises downward, creating a deep valley with nearly vertical walls, forming cliffs on both sides. This kind of deep, narrow valley with steep rock faces carved mainly by river erosion is called a canyon. In some regions the term gorge is also used for similar features, but canyon is the widely known term in world geography, especially in connection with famous examples like the Grand Canyon in the United States.

Step-by-Step Solution:
Step 1: Focus on the description: a deep valley between cliffs, carved from the landscape by a river. Step 2: Recall that the term canyon is commonly used for long, deep, narrow valleys with steep rock walls created by river erosion. Step 3: Compare this with plateau, which is an elevated flat or gently undulating region, not a deep valley. Step 4: Compare with plain, which is a broad flat lowland and not characterised by steep cliffs. Step 5: Conclude that canyon is the correct term that matches the description given in the question.

Verification / Alternative check:
To verify the answer, think of a well known example such as the Grand Canyon of the Colorado River. It is a tremendous deep valley with spectacular cliffs and layered rock walls, carved over millions of years by the river cutting down into the rock. Other examples include canyons in Central Asia, Africa, and many mountain regions where rivers have eroded deeply. In each case, the landform name used is canyon or sometimes gorge. The other option names do not apply to such deep, narrow, cliff sided valleys formed by river erosion, confirming that canyon is the correct answer.

Why Other Options Are Wrong:
Plateau: This is incorrect because a plateau is a relatively flat elevated surface and does not describe a deep valley between cliffs.
Plain: This is incorrect because a plain is a wide flat or gently rolling area of low relief, not a narrow steep sided valley.
Delta: This is incorrect because a delta is a depositional feature at a river mouth where sediments accumulate, often forming a roughly triangular shape, not a deep eroded valley.
Basin: This is incorrect because a basin is a broad low lying area where water or sediments collect; it does not necessarily have steep cliffs on both sides.

Common Pitfalls:
A common confusion is between canyon and valley in general. All canyons are valleys, but not all valleys are canyons. Canyons are specifically deep and steep sided, often with spectacular rock walls. Another pitfall is mixing up canyon with rift valley, which is created by tectonic forces rather than river erosion. Students should carefully read keywords such as carved by a river and presence of cliffs to select the correct landform name. Visualising famous examples like the Grand Canyon can help fix the concept in memory.

Final Answer:
A deep valley between cliffs often carved from the landscape by a river is called a canyon.