A deep, narrow valley with very steep, almost vertical sides, nearly as wide at the top as at the bottom, is called a:

A gorge is a deep, narrow valley with very steep, almost vertical sides, usually cut by a river through hard rock. Its width at the top is almost the same as its width at the bottom.

How gorges form:

• A river with a steep gradient and a large volume of water cuts down (vertical erosion) rapidly into hard, resistant rock.
• Since the rock on the sides is hard, it does not wear back easily, so the valley remains narrow with steep walls.
• Gorges are common in the upper courses of rivers, in mountainous areas, and where rivers cut through uplifted land.

Gorge and canyon:

• A canyon is also a deep valley with steep sides, but it is usually wider at the top than at the bottom, with step-like slopes.
• Canyons typically form in dry regions with horizontally layered sedimentary rocks, where the river cuts down while the sides are slowly worn back in steps.
• The Grand Canyon of the Colorado River in the USA is the most famous canyon.
• In general, a gorge is narrower and its sides are more vertical than those of a canyon.

Examples of gorges in India:

• The Indus, Sutlej and Brahmaputra cut deep gorges through the Himalayas; the Indus gorge near Nanga Parbat is one of the deepest in the world.
• The Marble Rocks gorge of the Narmada at Bhedaghat, Jabalpur.
• The Gandikota gorge on the Penna (Penner) river in Andhra Pradesh, called the "Grand Canyon of India".

Other river valley shapes:

• V-shaped valley: formed by river erosion in the upper course.
• U-shaped valley: formed by glacial erosion.
• Rift valley: formed by the sinking of land between faults.

Why not the other options?

• ✗A canyon is usually wider at the top, with step-like sides.
• ✗A rift valley is formed by faulting, not by river erosion.
• ✗A cirque is a bowl-shaped hollow formed by a glacier.