Weathering, Rivers & Coasts

Question 1

What is weathering?

Answer 1

Weathering is the weakening and breakdown of rocks in the place where they are (in situ)

Question 2

Biological weathering

Answer 2

The weakening and breakdown of rocks by plants and animals.

Roots of plants and burrowing animals get into the cracks and break them up

Question 3

Chemical weathering

Answer 3

Chemicals in the air and water react with rocks and break them down

Question 4

Physical/ mechanical weathering

Answer 4

Extreme changes in temperature cause the rocks to break apart. There are two types: freeze-thaw action and exfoliation (onion skin effect).

Question 5

Freeze thaw action

Answer 5

During the day, water enters the cracks.
At night, the water freezes and expands, this exerts pressure in the crack.
The next day, water thaws (melts).
The constant cycle widens the crack until breaking the rock.

Question 6

Exfoliation/onion skin effect

Answer 6

During the day, the surface of the rock heats and expands.
At night, the surface of the rock cools and contracts.
This makes the rock crack and peel of like an onion.

Question 7

Coastal erosion, explain:
Erosion
Transportation
Deposition

Answer 7

The sea wears the rock away.
The sea carries the eroded material.
The sea drops the eroded material.

Question 8

Hydraulic action

Answer 8

Waves break against the rocks and air is trapped in the cracks. This causes massive pressure which break rocks over time

Question 9

Abrasion/ Corrasion

Answer 9

Boulders, pebbles and sand are thrown against the bottom of the cliff by waves. This causes the undercutting of the cliff and break up of rocks.

Question 10

Solution/Corrosion

Answer 10

Chemicals in sea water dissolve rocks and wear them down

Question 11

Attrition

Answer 11

Pebbles transported by the sea bang each other. This make them smaller and smoother.

Question 12

How is the eroded material in the coast transported?

Answer 12

Longshore drift:

The waves move towards the coast at an angle (depending in the prevailing wind) and away in straight line.

Question 13

Bays and headlands

Answer 13

Bays are areas of soft rock where the sea has eroded the material more quickly than in a headland which are bits of harder rock that are not eroded so quickly.

Question 14

Caves, arches and stumps.

Answer 14

The sea attacks the cracks in a headland forming a cave.
The sea erodes the cave which turns into an arch.
The top of the arch collapses and a stack is left.
The stack is eroded so it turns into a stump.

Question 15

Evaporation

Answer 15

Water from water stores evaporates and rises because the warm air is less dense.

Question 16

Condensation

Answer 16

Water vapour cools and is more dense, clouds are formed.

Question 17

Precipitation

Answer 17

Water vapour is so dense that it falls in rain, snow, sleet etc.

Question 18

Interception

Answer 18

Some precipitation is intercepted by plants and goes back into the earth by the process of transpiration.

Question 19

Surface run-off

Answer 19

The earth is saturated so it can’t absorb water. Water flows quickly through the surface until the river.

Question 20

Through flow

Answer 20

Some water makes its way through the ground by cracks and spaces in the earth until they reach the river.

Question 21

Percolation

Answer 21

Water finds its way deep into the ground and slowly goes back to the river or the sea.

Question 22

River basin

Answer 22

Is the land that the water flows across or under on its way to the river. Like a bathtub, it catches all the water until it reaches the river in the middle of the river basin.

Question 23

Watershed

Answer 23

The edge of the river basin

Question 24

Source

Answer 24

Place where the river begins

Question 25

Tributaries and confluence

Answer 25

Small rivers that meet a bigger one

When the tributaries meet the main river.

Question 26

Mouth of the river

Answer 26

Where the river meets with the sea or ocean.

Question 27

Coastal deposition
Beaches
Spits
Bars

Answer 27

The sea deposits sand, pebbles and rocks.
Longshore drift moves large amounts of material and suddenly the longshore drift changes direction leaving an arm attached to the land by one end.
The spit gets bigger with eroded material and leaves a bar which separates the lagoon with the sea.

Question 28

Coastal erosion

Economic impacts

Answer 28

Buildings and land falling
Individuals without homes
Workers without jobs
Less tourism
Less facilities

Question 29

Coastal erosion

Social impacts

Answer 29

Stress related illnesses
Access to local areas reduced
Less facilities

Question 30

Coastal erosion

Environmental impacts

Answer 30

Habitats of animals being destroyed

Question 31

Groynes

Answer 31

Are placed along the beach to interrupt movement of sand by longshore drift.
Interrupting the natural movement of the sea could have negative impacts further up the coast.

Question 32

Sea walls

Answer 32

The walls absorb energy from the waves and prevent erosion as well as flooding.
Expensive to build and can cause environmental problems

Question 33

Beach rebuilding

Answer 33

Replaces sand taken away by the sea maintaining the natural beauty of beaches.
This is expensive to maintain in long term

Question 34

Riprap

Answer 34

Concrete blocks that absorb the waves’ energy before they impact the coast. So the waves don’t have so much power to erode the coast.
This is quite cost-effective but makes access to the beach quite difficult.

Question 35

Name the three stages of a river and their characteristics

Answer 35

Upper stage: v shaped valleys, interlocking Spurs, waterfalls.
Middle stage: wide river valleys, meanders, flood plains
Lower stage: ox bow lakes, levees, deltas

Question 36

How is eroded material carried down the river?

Answer 36

Rolling: large stones are rolled along the river bed.
Bouncing: smaller pebbles are bounced along the river bed.
Suspension: light material like sand floats around the river.
Solution: dissolved materials are carried by the river.