Detailed Summary
This section explains the concept of landforms, defined as small to medium parts of the Earth's surface, and landscapes created from multiple landforms. Every landform has distinct physical characteristics shaped by geomorphic processes. Two major aspects of landform evolution are introduced: the effect of running water and the stages of development: youth, maturity, and old age. In humid regions, running water is a significant geomorphic agent responsible for soil degradation. It operates through two forms: overland flow, which causes sheet erosion, and linear flow forming streams and rivers.
Stages of Landform Evolution:
- Youth Stage: Characterized by few, poorly integrated streams flowing over steep gradients, resulting in shallow V-shaped valleys. The streams show little to no floodplains, with the landscape featuring marshes and lakes.
- Mature Stage: Streams become plentiful with deep, V-shaped valleys and wider floodplains. The valleys transition to meandering courses, leading to the disappearance of sharp stream divides as the landscape matures.
- Old Age: The landscape features gentle gradients, meandering streams, and expansive floodplains. Most streams are lower in elevation, and features like oxbow lakes and wetlands become prominent.
The section highlights how natural processes evolve landscapes over time and outlines the critical role of climate in determining these changes.