1. Aim: Unit 8 Review Do Now: –Power on your laptops and download the test corrections template. –H.W. Finish your unit 8 test corrections.

2. Sorting of Sediments and Deposition

3. 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

4. Agents of Deposition Stream sediments and wind sediments get deposited when the speed or velocity of the eroding agent decreases enough so that the agent can no longer carry the sediment.

5. Settling Rate Vs. Velocity As the velocity (speed) of the wind or stream decreases, deposition begins – usually with the largest, heaviest, most dense, most rounded, particles settling out first. Velocity Settling Rate

6. Settling Rate Vs. Density Particle density affects settling rate. Particles with similar size and shape should settle at the same rate, but particles with a higher density will settle faster. Density Settling Rate

7. Settling Time Vs. Rate Be oh-so-careful when answering questions about which particles settle fastest. There is a HUGE difference between settling time and settling rate. Settling Time Settling Rate

8. Mountain side Stream Lake As the stream enters the lake or an ocean, the stream velocity decreases and sediments are deposited. S t r e a m v e l o c i t y d e c r e a s e s Sediments are deposited in size order horizontally. Horizontal Sorting B o u l d e r s C o b b l e s P e b b l e s S a n d S i l t C l a y

9. Region of maximum stream velocity changes when streams bend or turn. There is an interface between regions of erosion and deposition… Stream Boulders Cobbles Pebbles Sand Vertical Sorting Clay Silt Vertical Sorting

10. During vertical sorting the largest, roundest, most dense particles settle to the bottom with the smallest, flattest, least dense particles settling at the top. Latest layer Earliest layer Later 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 graded bed.

11. Vertical Sorting

12. Where a stream or river enters a lake or ocean, deposition begins at the mouth forming a delta. Named for the Greek letter Stream Ocean Deltas

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

14. Wind-born particles are generally sorted by size, but are small. Cross bedding is common in sand dunes. Sediments eroded and deposited by gravity are unsorted. Deposition by other agents of erosion

15. Crossbeds in a Sand Dune

16. Unsorted Sediments Unsorted till left behind by a Glacier. Unsorted sediments due to Mass Movement.

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