The Narmada and Tapi rivers flow westward to the Arabian Sea through:

The Narmada and Tapi flow westward through rift valleys, long troughs formed when blocks of the Earth's crust sank between parallel faults. This explains why they flow west, unlike most other rivers of the peninsula, which flow east.

What a rift valley is:

• A rift valley is a long, narrow depression formed when a block of land sinks between two parallel faults (cracks) in the Earth's crust.
• Such valleys are formed by tension, when the crust is pulled apart.

The Narmada rift valley:

• The Narmada flows west through a rift valley between the Vindhya Range to the north and the Satpura Range to the south.
• The faulting is linked to the movement of the Indian plate and the bending of the peninsular block, which also helped raise the Himalayas.

The Tapi rift valley:

The Tapi flows west in a similar trough south of the Satpura Range, roughly parallel to the Narmada.

Why most peninsular rivers flow east:

• The Peninsular Plateau is tilted, with the Western Ghats higher than the Eastern Ghats.
• So, rivers such as the Godavari, Krishna and Kaveri rise in the Western Ghats and flow east into the Bay of Bengal.
• The Narmada and Tapi are exceptions because they follow the rift valleys, which slope towards the west.

Features of rivers flowing in rift valleys:

• They are relatively straight, as they follow the line of the faults.
• They do not build large deltas at their mouths.
• They have few tributaries, especially on one side, since the valley walls are steep.

Other examples of rift valleys:

The Great Rift Valley of East Africa is the most famous rift valley in the world.

Why not the other options?

• ✗The Narmada and Tapi do not flow through deltas; deltas form at river mouths.
• ✗Glacial valleys are found in high mountains, not in central India.
• ✗Volcanic craters are circular depressions at the top of volcanoes.