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GEOL 1060 Geomorphology 1

Geomorphology GEOL 1060 Spring Semester 2007 Introduction

•  Geomorphology is the study of landforms –  Landforms can be analyzed differently depending

on the purpose of the study •  Traditional geomorphology was descriptive •  Modern geomorphology is more quantitative •  Field Oriented, requires experience gained

through fieldwork

Process •  Defined as the

action involved when a force induces change in the materials or forms at the earthʼs surface –  Physical –  Chemical

Process •  Processes are the link between

geomorphology and other fields –  Sedimentology - interpretation of stratigraphic

column –  Tectonics - analysis of plate boundaries –  Hydrology - understanding groundwater flow –  Geochronology - cosmogenic radionuclide dating,

luminescence dating –  Construction/engineering - landscape stability –  Hazard Assessment - landscape stability

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GEOL 1060 Geomorphology 2

Process Outline •  Landforms and processes exist in a

delicate equilibrium - systems •  Balance between process and form

created by force and resistance •  Changes that upset this equilibrium

cause system to seek new state of equilibrium - thresholds

Process Outline •  Processes can be linked so the effect of one

process may initiate action in another •  Time framework is critical in understanding

process •  Human vs geologic timescale

Alluvial Fan in Cross-Section

Balance and Systems •  Early geomorphology viewed changes as

gradual - balance between process and form •  Later theories viewed landforms as

continuously evolving through time •  Dynamic equilibrium concept incorporated the

two ideas and placed renewed emphasis on balance between process and form (1960ʼs)

Balance and Systems •  Modern theory incorporates these ideas into a

larger framework by considering form and process as systems or parts of systems (collection of related components)

•  Advantages –  Emphasizes relationship between process and

form –  Stresses multivariate nature of geomorphology –  Shows that some forms may be caused by

conditions that are no longer operating - out of balance/no modern analogue

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GEOL 1060 Geomorphology 3

Equilibrium •  Difficult to properly define in a complex

landscape system - use caution! –  Equilibrium implies unchanging, requires that

controlling factors (tectonics, climate, etc.) remain stable - usually not the case

–  Multiple definitions depending on time interval under consideration

–  Time intervals used in definitions of equilibrium •  Cyclic - millions of years •  Graded - 100ʼs to 1000ʼs of years •  Steady - days or months

Equilibrium •  Static Equilibrium - exists over short steady-

time intervals; landforms are generally unchanging and time-independent

•  Steady-State Equilibrium - exists over graded time intervals; changes occur, but offsetting effects tend to maintain system in constant average condition

•  Dynamic Equilibrium - exists over cyclic time intervals; average condition of the system is progressively changing