Sorting of Sediments and Deposition

Agents of Deposition

• The agents of erosion are also agents of deposition.

• Depositional rate depends on sediment size, shape and density.

• Depositional rate also depends on characteristics of the depositional agent.

Speed or velocity

Agents of Deposition

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Settling Rate Vs. Velocity

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Velocity

Sett

ling

Rate

Settling Rate Vs. Density

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Density

Sett

ling

Rate

Settling Time Vs. Rate

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Settling Time

Sett

ling

Rate

Mountain side

Stream

Lake

As the stream enters the lake or an ocean, the stream velocity decreases

and sediments are deposited.

Stream velocity

decreases

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Horizontal Sorting

BouldersCobbles

PebblesSand Silt Clay

Region of maximum stream velocity changes when streams bend or turn. There is an interface between regions of erosion and deposition…

Stream

BouldersCobblesPebblesSand

Vertical SortingClay

Silt

Vertical Sorting

Vertical Sorting

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Vertical Sorting

Latest layer

Earliest layerLater layer

•Vertical sorting can occur as a single depositional event in still water or a series of events as when a stream’s velocity decreases through the seasons allowing particles to settle in a -

Vertical Sorting

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Named for the Greek letter

Stream

Ocean

Deltas

Mississippi Delta• Sediment-laden

river water mixes with cold, deep-sea currents, creating a nutrient rich zone where both salt and freshwater fish flourish.

• Wind--• -

Deposition by other agents of erosion

Crossbeds in a Sand Dune

Unsorted Sediments

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Final Question

• What are the factors that affect the settling rates of sediments?

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