Glacial Trough Formation Explained

This question asks about the characteristics of glacial troughs and fiords. Let's analyze each statement:

Statement 1 Analysis: Glacial Troughs

The first statement says that Alpine glaciers remove soil, regolith, and sediment from valleys, shaping them into glacial troughs. This is accurate. Glaciers possess immense erosional power. As they move downslope, they:

• Scrape and pluck rock material from the valley floor and sides.
• Transport large amounts of debris.
• Widen and deepen existing river valleys.

This process transforms typically V-shaped river valleys into characteristic U-shaped valleys, known as glacial troughs. The immense weight and abrasive action of the ice effectively strips away the valley's surface material.

Statement 2 Analysis: Fiords

The second statement describes how seawater enters a glacial trough when the sea level is below the trough floor as the ice melts back, creating a fiord. This statement is also correct.

• Glacial troughs that extend below current sea level are often flooded by the sea when the glacier retreats.
• These flooded glacial troughs are called fiords (or fjords).
• Fiords are typically long, narrow, deep inlets with steep sides, characteristic of drowned glacial valleys.

Therefore, the process described accurately defines the formation of a fiord from a glacial trough.

Conclusion

Both statement 1, describing the formation of glacial troughs by glacial erosion, and statement 2, explaining how glacial troughs can become fiords when flooded by the sea, are correct.