What is geomorphology?Definitions

• geo = earth

• morph = form

• -ology = study of

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What is geomorphology?Definitions

• Surface features

• Surface processes

• Surface materials

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What is geomorphology?Definitions

• Study of landforms and landscapes

– Types of landforms

• Hills, valleys, floodplains, sinkholes, moraines, etc.

– Types of landscapes

• Karst, Fluvial, Glacial

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What is geomorphology?Definitions

• Study of surface processes responsible for landforms / landscapes

– A sub-discipline is process geomorphology– Current processes– Past processes

• Relict landscapes/landforms ( = paleoforms). • Relic is something that has survived decay or deterioration.

Example of a relict landscape?

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What past processes created this relict landscape?

What modern processes are modifying it?

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Were the processes that created the relict landforms destructional or constructional?

Are the modern processes modifying this landscapedestructional or constructional?

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What past processes created this relict landscape?

What modern processes are modifying it?7

Were the processes that created the relict landforms destructional or constructional?

Are the modern processes modifying this landscapedestructional or constructional? 8

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What is geomorphology?Scale

Consider scale of earth’s surface features

• How does scale of features relate to age?

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The Earth: the ultimate landform

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• Scale of landforms varies over 15 (!) orders of magnitude.• continents (107 km2) to microscale features like ripples, glacial striations (10-8 km2).

• Age of landforms varies over 7-8 orders of magnitude.• continents (109 years) to microscale features like pools and riffles (102 years).

• Larger landforms most durable (longer-lasting).•Smaller landforms created/destroyed faster than larger ones.

• Rates of geomorphic / geologic change slow for larger areas, faster when measured over small areas.

• example: earthquakes compared to glaciers• rate of erosion in small watershed compared to larger one

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William MorrisDavis introduced idea that landforms can be explained by one

--or usually a combination-- of the following:

Structure: rock mass (or unconsolidated material mass).

Process: constructive or destructive process(es) acting now orpreviously on structure.

Time (stage): landforms evolve through stages from continuedactions of geomorphic process(es).

Summary: “some rock (or soil/sediment) mass is being altered by some process, and the alteration has proceeded to a definable extent (stage)over a definite interval.” (Bloom, 1998) 15

StructureStructure ProcessProcess

TimeTimeResulting Landform

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Example

Structure: Limestone bedrock (Paleozoic)

Process: Dissolution (Cenozoic)

Time: 10,000 years

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Structure? Process? Time?

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Structure: limestone bedrock Process: weathering (dissolution)Time: 103 to 106 years?

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Structure? Process? Time?

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Structure: delta sediments Process: deposition / erosionTime: 103 to 104 years?

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What is geomorphology?

• Study of landforms and landscapes (the “what”).

• Study of surface processes responsible for landforms / landscapes (the “why”).

• Relationship between landform scale and age.

• Landforms can be explained in terms of structure, process and time.

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