Erosional Agents

Question 1

What are the five erosional agents?

Answer 1

Running water, wind, waves, glaciers, mass wasting

Question 2

What is the most important single agent of Erosion?

Answer 2

Running water

Question 3

True or false: ALL erosional agents work in the same way.

Answer 3

True

Question 4

What is the process erosional agents work in?

Answer 4

Erosion > Transportation > Deposition

Question 5

What is fluvial erosion?

Answer 5

Higher velocity = higher potential erosion (flow velocity)

Question 6

Flow velocity is the function of what two functions?

Answer 6

Slope gradient and discharge

Question 7

What are two types of erosion?

Answer 7

Hydraulic action and abrasion

Question 8

Hydraulic action?

Answer 8

“force of water can erode rocks” high velocity = high erosion

Question 9

Abrasion?

Answer 9

Add sediments (clasts > rocks)
Chipping and grinning effect. (pot wholes)

Question 10

What is slope gradient?

Answer 10

Steepness

Question 11

What is discharge?

Answer 11

Volume > amount of water (cfs)

Question 12

What is the chipping and grinning effect?

Answer 12

Turns rocks into rounded river rocks over a long period of time after chipping and grinning against others rock flowing down a body of water (river). Creates sculpted canyons.

Question 13

What is fluvial transportation?

Answer 13

“channel flow”

Question 14

A bed-load consists of what three functions?

Answer 14

Traction, sailtation, and suspended load.

Question 15

Traction?

Answer 15

Rolling and sliding of large materials

Question 16

Sailtation?

Answer 16

hopping and skipping of small materials

Question 17

Suspended load?

Answer 17

Very fine particles suspended in flow, slow to settle, gives color to the water.

Question 18

In most streams what is the largest portion of the bed-load?

Answer 18

Suspended load

Question 19

What is a thalweg?

Answer 19

Area of the fastest current. Flows from outside curve to outside curve.

Question 20

What do thalwegs create?

Answer 20

The erosion from the thalweg creates a cutbank on the outside curve.

Question 21

What do cutbanks create?

Answer 21

Oxbows (meandering river)

Question 22

Fluvial Deposition?

Answer 22

Erosion wears down landforms. deposition creates new landforms

Question 23

Deposition occurs when?

Answer 23

when velocity is in adequate to transport the land

Question 24

What two changes can cause a change in velocity?

Answer 24

Discharge and slope

Question 25

Sediments are deposited and sorted how?

Answer 25

By size and weight

Question 26

Landform of deposion is made up of what three functions?

Answer 26

Sand Bar (Point bar), Delta, Alluvial fan

Question 27

What is a sand bar?

Answer 27

Develops on the inside curve.

Question 28

What is a delta?

Answer 28

Perennial river year around thus always there. Forms at the mouth of a river where the river empties into the ocean.

Question 29

What is the largest delta in the world?

Answer 29

Indus river delta

Question 30

What does it mean to be delta-less? and what would be an example?

Answer 30

A river with no connection to the ocean (has not delta) Amazon river in an example of this.

Question 31

What is alluvial fan?

Answer 31

Alluvium = stream deposits.
Ephemeral stream (dry creek)
Short lived, but high velocity episodes

Question 32

How does a alluvial fan develop?

Answer 32

In avid regions, mts./desert floor.

Develops where mts. canyons open onto the desert floor

Question 33

What happens when alluvial fans over lap?

Answer 33

Causes a Bajada. ex.) Death Valley