What are the basic differences between glacial valleys and river valleys?
Glacial valleys are trough-like and U-shaped with broad floors and relatively smooth, steep sides. They may contain debris shaped as moraines, lakes gouged out of rocky floor, and hanging valleys at an elevation on one or both sides of the main valley.
In contrast, river valleys start as small and narrow rills which develop into gullies and then into valleys. They are typically V-shaped and can develop into gorges (deep valleys with very steep to straight sides) or canyons (with steep step-like side slopes). River valleys depend on the type and structure of rocks in which they form.
Explanation
The textbook clearly distinguishes between the two valley types. Glacial valleys (formed by glaciers) are U-shaped troughs with broad floors, steep smooth sides, and may have hanging valleys and moraines. River valleys (formed by water erosion) are V-shaped, starting from rills and gullies, and can form gorges or canyons depending on rock structure. The key difference lies in their shape (U vs V) and formation process.