Correct Option
The correct option is 1 and 3 only.
Explanation
Valleys are significant erosional landforms created by running water. They evolve from small rills into gullies and eventually into distinct valley forms. Depending on the dimensions, shape, and underlying geology, deep valleys are classified primarily into gorges and canyons.
Statement-wise Analysis
- Statement 1 is Correct: A gorge is a deep valley with very steep to straight sides. A defining characteristic of a gorge is that its width is almost equal at both its top and its bottom.
- Statement 2 is Incorrect: A canyon is a variant of a gorge but possesses distinct structural differences. A canyon is characterized by steep, step-like side slopes and is wider at its top than at its bottom. It is not equal in width throughout its depth.
- Statement 3 is Correct: The formation of these landforms is influenced by the type and structure of rocks. Canyons commonly form in horizontal bedded sedimentary rocks, whereas gorges are typically formed in hard rocks.
Key Takeaway
Gorges have nearly equal width at the top and bottom with steep, straight sides (hard rocks), whereas Canyons are wider at the top than the bottom with step-like slopes (sedimentary rocks).