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.

• Agents of Deposition

• Settling Rate Vs. Velocity Velocity

• Settling Rate Vs. Density Density

• Settling Time Vs. Rate Settling Time

-

Horizontal Sorting

As the stream enters the lake or an ocean, the stream velocity decreases and sediments are deposited.

Lake

Vertical Sorting

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

Vertical Sorting

• • 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 Latest layer Later layer Earliest layer

Vertical Sorting

Named for the Greek letter

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.

Deposition by other agents of erosion • • Wind --

Crossbeds in a Sand Dune

• Unsorted Sediments • -

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

---