Erosion and Deposition

trextemperMécanique

22 févr. 2014 (il y a 3 années et 4 mois)

301 vue(s)

Erosion and Deposition

1. What is the greatest driving force for all erosion?



Gravity

2. What is the greatest agent of erosion?



Running water (Streams, Rivers)

3. What agent of erosion is responsible for carving out V
-
shaped valleys?



Rivers

4. What agent of erosion is responsible for carving out U
-
shaped valleys?



Glaciers

5. What is the relationship between slope and rate of erosion?



As slope increases, erosion rate increases (Direct)

6. What is the relati
onship between stream discharge and rate of erosion?



As stream discharge increases, erosion rate increases (Direct)

7. In a meandering stream, where is erosion the greatest?



Outside of a meander



8. In a meandering stream, where is vel
ocity the greatest?



Outside of a meander

9. In a straight channeled stream, where is the velocity the greatest?



In the center, below the surface

10. What is an oxbow lake?



A cutoff from a meandering stream caused by extensive er
osion on the
outside of a meander.

11. What is the relationship between transported particle size and stream velocity? (ESRT
page 6)



As the stream velocity increases transported particle size increases (Direct)


12. What is the minimum speed need
ed to move a particle 0.2 cm in diameter? (ESRT page
6)



10 cm/s

13. Name some characteristics of wind erosion



Active in deserts and beaches, weathering by abrasion, pitted appearance,
Ventifacts (rocks with flat surfaces due to wind
-
blow
n sand abrasion)

14. How can wind direction be determined by looking at a sand dune?


Wind blows toward the gentle slope of a dune and deposits over the steep
slope.

15. a. Describe

the

relationship between

particle size and settling time



A
s particle size increases, settling time decreases (Indirect)



b. Describe

the relationship between

particle size affects settling rate



As particle size increases, settling rate increases (Direct)

16. a. Describe the relationship between pa
rticle shape and settling time



As particle shape becomes more spherical, settling time decreases



b. Describe the relationship between particle shape and settling rate



As particle shape becomes more spherical, settling rate increase
s.

17. a. Describe the relationship between particle density and settling time



As particle density increases, settling time decreases (Indirect)



b. Describe the relationship between particle density and settling rate



As particle de
nsity increases, settling rate increases (Indirect)

18. Describe the relationship between slope and rate of rate of deposition



As slope increases, rate of deposition decreases (Indirect)

19. Describe the relationship between stream velocity and ra
te of deposition



As stream velocity increases, rate of deposition decreases (Indirect)


20. Describe the relationship between stream discharge and rate of deposition



As stream discharge increases, rate of deposition decreases (Indirect)

21. Where is deposition the greatest in a river system? Why?



Inside of a meander or Mouth of a River because Stream Velocity decreases

22. What agent of erosion leaves behind a pile of unsorted sediments?



Glaciers

23. How does graded bedd
ing deposition develop?



Vertical sorting of sediment
-

When a large mass of sediment is deposited in
a quiet body of water. Example : A landslide dumps sediment into a lake. All the
large sized particles deposit first on the bottom and size increas
es to the top of a
graded bed.

24.

What causes

horizontal sorting of sediments?



When a stream/river enters a larger body of water such as the ocean. The
river's velocity slows down and large sediment is deposited first, as distance from
the shore

increases size decreases.

25.

Explain how sediments are carried in moving water in solution, suspension, Floatation
and bed load



The smallest sediments are
dissolved
in water are carried in water in
solution.

Ions of salt such as sodium and chlor
ine are carried in water by solution.



Sediments carried in
suspension

are small enough that they settle out of the
water very slowly. Silt and clay in suspension gives streams a muddy appearance.
(Ole Muddy Mississippi)



Fresh leaves, tree b
ranches, and other organic remains are less dense than
water and
float
on the surface.



If a stream is flowing quick enough, sediments roll or bounce along the
bottom of the stream as
bed load.


26.

How is

till, erratics, and striations evidence of g
lacial erosion and deposition?



Till is a pile of unsorted glacial sediment



Erratics are large boulders deposited by glaciers



Striations are scratches on the bedrock caused by the moving ice carrying
sediments and scraping the sur
face of the earth