Penck's Landscape Model: Absteigende Entwicklung Phase

Penck's model outlines landscape evolution stages. The 'Absteigende entwickelung' specifically refers to the descending or degradation phase.

Understanding the Descending Phase

This phase occurs when erosional forces significantly reduce the landmass's elevation after tectonic uplift has ceased or slowed considerably. The primary processes involve the wearing down of the landscape.

Characteristics of Absteigende Entwicklung

• Erosion Dominance: Erosion becomes the dominant process, actively removing material.
• Absolute Height Reduction: The overall elevation of the land surface decreases over time.
• Relative Relief Diminution: The difference in height between the highest and lowest points (e.g., peaks and valleys) becomes smaller, leading to a less dramatic topography.

Option 4 correctly identifies that in this phase, both the absolute height and relative relief of the landscape decline.

Why Other Options Are Incorrect

• Option 1 focuses on specific geomorphic processes (valley deepening vs. widening) rather than the overall phase characteristic.
• Option 2 describes a phase of net uplift ('rate of upliftment is more than rate of erosion'), which is characteristic of earlier, rising phases, not the descending phase.
• Option 3 presents a contradiction. While relative relief might decrease, absolute height typically decreases, not increases, during the descending phase.

Therefore, the defining characteristic of Penck's Absteigende entwickelung phase is the decline in both absolute height and relative relief.