Rift valleys are formed through which of the following processes?

Step 1: Analyze the question The question asks which process forms rift valleys. A rift valley is a long, narrow depression bounded by roughly parallel fractures in the earth's crust.

Step 2: Explain the concept Rift valleys are formed by faulting, which is the fracturing and displacement of rock along lines of weakness in the earth's crust. These forces are tectonic (internal forces).

There are two main explanations:

• Tension theory: Tensional forces pull the crust apart. Two parallel faults develop, and the block of land between them sinks (the down-thrown block or graben) while the sides stay high.
• Compression theory: Compressional forces push the crust inward. The side blocks are pushed up and over the middle block, leaving a depression between them.

In both cases, the valley is made by movement along faults.

Step 3: Eliminate the other options

• A. Erosion: Erosion wears down land and carves valleys (e.g. river V-shaped valleys), but it does not create rift valleys.
• B. Folding: Folding bends rock layers and forms fold mountains (e.g. the Alps, Himalayas) and not rift valleys.
• C. Weathering: Weathering breaks down rocks in place. It is not a mountain-building or crust-fracturing process.
• D. Faulting: Correct. Faulting produces rift valleys, block mountains and horsts.

Step 4: Answer The correct option is D. Faulting.

Examples to remember:

• The East African Rift Valley (Kenya, Ethiopia, Tanzania)
• The Rhine Rift Valley (Germany/France)
• The Red Sea and Dead Sea rift
• In Nigeria, the Benue Trough is often linked to rifting.

Exam tip: Link the landform to its process:

• Folding → Fold mountains
• Faulting → Rift valleys and block mountains (horsts)
• Volcanicity → Volcanoes and lava plateaus

If you see "fault," "graben," "horst," or "rift," think faulting!