The correct option is 1 and 3 only.
Explanation
Glaciers are powerful agents of erosion that modify pre-existing landscapes. As glaciers move through river valleys, they transform the topography through processes such as abrasion and plucking, creating distinct erosional landforms characterized by steep slopes and flat floors.
Statement-wise Analysis
- Statement 1 is Correct: Glacial valleys, also known as glacial troughs, are typically U-shaped. Unlike river valleys which are V-shaped, glaciers erode the valley walls as well as the floor. This lateral and vertical erosion results in a valley with a broad, flat floor and steep, vertical sides.
- Statement 2 is Incorrect: Hanging valleys are a characteristic feature of glaciated regions. They are formed when tributary glaciers, which have less mass and erosive power than the main glacier, join the main valley. After the ice melts, the floor of the tributary valley is left suspended high above the floor of the main valley, often resulting in waterfalls.
- Statement 3 is Correct: Fjords are deep, steep-sided glacial troughs that have been submerged by seawater. They are formed when glaciers erode valleys below the current sea level or when sea levels rise (post-glaciation) to inundate the coastal glacial valleys. They are prominent in high-latitude regions like Norway and Chile.
Key Takeaway
Key Takeaway: Glacial erosion transforms V-shaped river valleys into U-shaped troughs. Hanging valleys are tributary valleys left high above the main floor, and Fjords are submerged glacial troughs forming deep coastal inlets.