Surface 2: Introducing Process and Form

Define geomorphic processes

Geomorphic processes are the means by which the Earth’s surface undergoes modification.

Examples of endogenic processes

• tectonic movements

• volcanic activity

Examples of exogenic processes

• weathering

• erosion by wind, water, ice

Form system

• focuses on the physical characteristics of landforms

• e.g. slope/shape

Process-response system

• emphasizes the interactions between processes

• e.g. erosion and the resulting landforms (valleys)

Concept: Geomorphic system + example

• a framework for understanding the interactions between landforms and processes that shape them

• e.g. a river system involves processes like erosion and deposition → shape the river’s channel and floodplain

Key components of a hillslope system

• Storages: soil, regolith

• Inputs: rainfall, sediment deposition

• Outputs: erosion, runoff

• Throughputs: water movement, sediment movement down the slope

Negative feedback in geomorphic systems

• occurs when a change in one part of a system counteracts changes in another part, leading to stability

Example of negative feedback

If erosion increases on a slope → deposition may increase at the base → stabilizing the slope

Positive feedback in geomorphic systems

• amplifies changes in a system

Example of positive feedback

Slope becomes steeper due to erosion → may become more unstable → further erosion

Role of models in geomorphology

• to simulate and predict the behavior of geomorphic systems

Example: models in geomorphology

• numerical models can simulate how a hillslope evolves over time under different conditions of rainfall and erosion

Equilibrium in geomorphic systems

• refers to a balance between opposing forces or processes

• e.g. a river may reach equilibrium when the rate of sediment deposition = the rate of sediment erosion

Complex response in geomorphic systems

• the idea that geomorphic systems may not respond linearly to changes

• small changes in one part of the system can lead to disproportionate or unexpected responses in another part

Thresholds

• critical points in a system where a small change can lead to a significant response

• e.g. a slope may remain stable until a certain level of rainfall is reached, at which point a landslide may occur