Fluvial Processes And Terrain

Question 1

What is an eolian deposit?

Answer 1

Deposited by wind

Question 2

What is hydraulic action?

Answer 2

Movement of water dislodged material and carrying it downriver

Question 3

What is bed load?

Answer 3

Coarse particles that move along the stream bed
Sands and gravels typically, don’t suspend well in water
10 percent of total load
Tumbles along the bottom

Question 4

What is suspended load?

Answer 4

Can account for most of the load
Small particles, fine sands, silts, and clays
Stays suspended in moving water but settles in calm water

Question 5

What is dissolved load?

Answer 5

Ions in solution, can’t be seen by the eye
Might precipitate out of a solution
Ie calcium carbonate

Question 6

What impacts deposition of material by water?

Answer 6

Velocity.
Velocity of water sorts the material as larger particles need greater Velocity to be deposited. So as water Velocity decreases, deposits are dropped by size and therefore sorted.

Question 7

What indicates something is a fluvial deposit?

Answer 7

Rounded rocks
Sorting
Sand without any silt or clay.

Question 8

How does particles size influence channels

Answer 8

If the material the river is cutting or depositing sand and gravel the channel tends to be wide and shallow
Sand is non cohesive and easily eroded, sides get eroded but bottom doesn’t

If the material is silt or clay, the channel tends to be more deep and narrow.
Silt is cohesive, less easy to erode.

Question 9

What happens with meandering in rivers in terms of deposition?

Answer 9

Slower water by the point bars deposits more material, they build up

Question 10

How are oxbow lakes formed?

Answer 10

Meandering river systems. Erosion from corners across each other are the neck and eventually the erosion will meet and create an oxbow.

Question 11

Why does a river braid?

Answer 11

It’s depositing so much material (bed load) and the velocity can’t move it, it forms islands by going around it

Rivers carry a high bedload from a steep valley, when the elevation drops off and the velocity slows to it braids

Load exceeds capacity, common at the end of glaciers

Question 12

What are levees and how do they happen?

Answer 12

Many are human made, rocks beside the creek.
Attempts to prevent flooding.
Natural levees can occur in flood systems where coarses material is deposited on channel edges

Question 13

What is a meander scar?

Answer 13

Dried up oxbow lake.

Question 14

What is a fluvial fan

Answer 14

Material coming down a steep gradient to a gentle valley.
When the velocity decreases at the bottom it deposits the material.

Question 15

What’s the difference between a fluvial fan and colluvial cone?

Answer 15

Gravity is a bigger factor for a cone, usually steeper

Question 16

What are river terraces?

Answer 16

After glaciation, material is stabilized by vegetation resulting in a decreased load being carried.
More downcutting occurs as less energy is needed to move material.

When there’s moving water over a wide area it forms a flat landscape.

Question 17

What forms paired terraces?

Answer 17

Material deposition of the center of the valley fills up, leaving matching terraces on either side from where the river was wide and braided.

As the bedloads decreased, velocity increases and more downcutting occurs as the river goes from braided to a channel.

Series of downcutting forms matching terraces.

Question 18

What are kettle holes?

Answer 18

Found on kame terraces, terraces formed when the valley had ice in it.

They are formed by chunks of ice breaking off a glacier and sitting in the flow of a river. Material accumulates around but not under them and then when they melt they leave depressions/holes

Question 19

How does the terrain texture key/initials break dowm

Answer 19

First two or three letters = terrain texture, the soil pits description

Second big letter: surficial material

Then surface expression

Then geomorpological processs

(qualifiers, ie I for inactive or A for inactive, usually used with the surficial material and rarely for geormorpological processes)

Question 20

What is gravel? What is mud? What is a block? what is a boulder?

Answer 20

Gravel is a rounded coarse fragment deposited by water, greater than 2m

Mud is a mix of silt and clay.

Block is an angular particle greater than 256mm
A boulder is a rounded particle greater than 256mm