Geography/Geology 352: Geomorphology

INTRODUCTION TO GEOMORPHOLOGY

A. Geomorphology

• the study of landforms

• involves systematic description of landforms

• involves analysis of formation and modification processes

B. Landform Controls

1. Driving forces (sources of energy)

• solar radiation

• gravity

• earth's internal heat

2. Resisting forces

• lithology

• geologic structure

3. Processes: how energy is utilized; how driving and resisting forces interact

• internally driven processes

• externally driven processes

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C. Equilibrium

• results from balance between driving and resisting forces

1. Equilibrium and time

• static equilibrium: landforms show no apparent change

  • time span: hours, days, months

• steady-state equilibrium: fluctuations about an average condition

• time span: years, decades, centuries

• dynamic equilibrium: system changes progressively

  • time span: millions of year

• form remains constant provided fundamental controls don't change

2. Thresholds: the limits to equilibrium

• disequilibrium: driving and resisting forces out of balance

• thresholds difficult to define

  • lag time: delay time between when fundamental controls change and the landscape responds

  • relict landforms: landforms created under previous climatic conditions

  • landscape shows complex response

3. Temporary versus geomorphically significant disequilibrium

• relaxation time or recovery time: time required for system to return to equilibrium condition after being in disequilibrium

• feedback

  • negative - helps prevent change; helps maintain temporary disequilibrium

  • positive - helps promote change; helps create geomorphically significant disequilibrium

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D. Systems Approach to Geomorphology

• morphological systems: examine morphological properties of landforms or landscape elements

• cascading systems: examine movements of mass and flows of energy through the landscape

• process-response systems: examine interactions between morphological and cascading systems; examine relationship between adjustments in process and form

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E. Summary

• landforms result from interaction of driving forces, resisting forces, & processes

• landform modification is related to equilibrium and thresholds

• landscapes are systems with multiple interacting elements