Weathering and Erosion

Question 0

Define Erosion.

Answer 0

• It is the breaking up and wearing away of rocks by moving water, ice or wind.

Question 1

Define the term weathering.

Answer 1

• it is the disintegration and decomposition of rock in its original position.
• rocks that has been broken down remains in original position.

Question 2

Define Transportation ( deposition )

Answer 2

• the carrying away of loos rock material produced by erosion and weathering, by wind, ice or water.

Question 3

What is mass wasting?

Answer 3

• it is the gradual movement of weathered materials down a slope under the influence of gravity.

Question 4

Name the types of weathering.

Answer 4

1. physical .
2. chemical.
3. biological.

Question 5

Name two examples of physical weathering.

Answer 5

1. frost shattering.

2. exfoliation.

Question 6

Describe Exfoliation.

Answer 6

• particularly noticeable in hot desert regions.
• During the day a rock expands from the heat.
• during the night the rock contracts from the cold.
• this constant heating and cooling puts the top few cm of the rock under stress.
• cracks will appear which will deepen and eventually pieces will peal off.
• Dome that forms: exfoliation dome
• rock fragments at base: scree of talus.

Question 7

Explain what is Frost shattering.

Answer 7

• especially in regions with a wet, cold climate.
• water fills crack in rocks.
• during night the water freezes and expands.
• this widens the cracks.
• during day the ice melts and sinks deeper into the wider crack.
• this constant process eventually breaks pieces of the rock.
• gives mountains to be sharp and pointy.

Question 8

Describe chemical weathering.

Answer 8

• it is when the rocks undergoes chemical changes.

- most rapid in warm, moist regions.

Question 9

Give two examples of chemical weathering and explain them.

Answer 9

1. Oxidation.
   - Oxygen from the atmosphere oxidises minerals in broken rocks.
   - iron can be turned to rust.
2. Carbonation.
   - Common in limestone and chalk areas.
   - rainwater dissolves carbon dioxide in atmosphere.
   - forms a weak carbonic acid.
   - acid works in joints in rocks.
   - joints become wider untill cracks called grykes form.
   - eg. Cango caves.

Question 10

Describe biological weathering thoroughly. with examples.

Answer 10

• it is when animals and plants help to break down rock.
• Roots of plants can grow into cracks and force them wider.
• roots also secrease weak acid to dissolve minerals.
• burrowing animals like rabbits also help.
• some animal secrete acids , like limpids.

Question 11

Give the conditions needed for mass wasting to occur.

Answer 11

• The resistance of the weathered material must be overcome by gravity. usually helped by water.
• the steeper the slope and the heavier the material, the easier the resistance is overcome.

Question 12

name and explain four ways that mass wasting occurs.

Answer 12

1. Soil creep.
   - the steady downward movement of soil on sloping land.
2. rain wets the soil.
3. alternate heating and cooling can also loosen the particles.
4. grazing animals can looses soil and cause soil creep.
   - it is a slow movement.
5. Mud flows.
   - when mud flows down hill.
   - it is sudden and faster than soil creep.
   - Heavy rain in a area can cause it.
   - Sudden storm in a desert can cause a mudflow.
   - Slopes of volcanoes can also cause mudflow if ash is turn to mud by water.
6. Landslides.
   - when large quantities of weathered materials slide down a steep slope.
   - earthquakes, volcanoes or heavy rain can trigger landslides.
7. Rock falls.
   - when rock fall down a cliff or very steep slope.
   - most rapid type of mass wasting.
   - can result in a talus slope.