1.2 Physical processes give rise to characteristic river landforms

Question 1

Define weathering:

Answer 1

Involves elements of weather wearing away something

Question 2

Define physical weathering:

Answer 2

Breaks down rock into smaller pieces, changes in temperature and rainfall freezing and thawing in rock cracks

Question 3

Describe freeze thaw action:

Answer 3

Water seeps into cracks of rocks and freezes and expands breaking rock

Question 4

Describe exfoliation (onion):

Answer 4

Occurs as internal of rock expands from heat and while outside cools quicker contracting and breaking rock

Question 5

Define chemical weathering:

Answer 5

This causes rock to decay and disintegrate. Largely done by slightly acidic rainfall seeping into porous rock

Question 6

Describe hydrolysis:

Answer 6

When water dissolves minerals in rock

Question 7

Describe oxidation:

Answer 7

Reacting with oxygen

Question 8

Describe acid rain:

Answer 8

Weak acid formed when water and CO2 react wearing rock

Question 9

Define biological weathering:

Answer 9

Roots of plant growing in cracks in rocks gradually split rock apart

Question 10

Define mass movement:

Answer 10

Once rocks broken down weathered material moves down under influence of gravity.

Question 11

Describe slumping:

Answer 11

When bottom of valley slope cut away by river at base, slope unstable and weather material slumps down. Rain acts as lubricant and makes material heavier.

Question 12

Describe soil creep:

Answer 12

Weathered material moves down slope slowly, collects at bottom and is eroded by river

Question 13

Define attrition:

Answer 13

large particles such as boulders collide breaking into smaller pieces

Question 14

Define hydraulic action:

Answer 14

Sheer force of the river dislodges particles

Question 15

Define abrasion:

Answer 15

Smaller particles rub against river banks and bed

Question 16

Define solution in terms of erosion:

Answer 16

Acid in rivers dissolve rocks

Question 17

What is transport in river?

Answer 17

Material known as load moving along the river

Question 18

Describe traction (transport):

Answer 18

Large boulders rolled along the bed

Question 19

Describe saltation (transport):

Answer 19

Rocks bounce along the bed

Question 20

Describe suspension (transport):

Answer 20

Lighter material carried by river flow

Question 21

Describe solution (transport):

Answer 21

Material dissolved in river

Question 22

Describe deposition:

Answer 22

When the river lacks energy to carry load heavier particles begin to get deposited, when less water or where current slows, Large boulders deposited at top and small at end resulting in sorting

Question 23

How does a river change downstream?

Answer 23

Increases:
Discharge, channel width, channel depth, velocity, load

Decreases:
Particle size, Channel bed roughness, Slope

Question 24

Describe formation of V-Shaped valley:

Answer 24

Formed by erosion, rocks and stones carried. Force of water and grinding causes vertical erosion to carve out valley. Gets deeper and wider over time. Interlocking spurs formed as weaker parts cut.

Question 25

Describe formation of waterfalls:

Answer 25

Water flows over hard rock which erodes slowly and beneath softer rock eroded faster to form a step. Force of water erodes bottom to form plunge pool. Hard rock gets undercut soft rock erodes so it eventually collapses.

Question 26

Describe formation of meanders:

Answer 26

Lateral erosion as softer rock eroded faster causing a bend and deposition occurs on slower part of bend making the bend less straight as faster part also cuts fast part of bend quicker.

Question 27

Describe formation of oxbow lakes:

Answer 27

When neck of meander comes narrow water begins to straighten its course cutting right through the bend and deposition occurs on bank of river and the cut off meander is an oxbow lake

Question 28

Describe formation of levees:

Answer 28

When river floods coarsest material deposited an edges of river forming natural embankment.

Question 29

Describe formation of deltas:

Answer 29

Occurs where river carries large amount of sediment which get deposited where river meets sea causing main channel to split into smaller channels/dis-tributaries

Question 30

Describe formation of flood plain:

Answer 30

As meander moves down slowly valley erodes to create wide valley floor, deposits layers of alluvial on slip off slopes builds up into large flood plain