Chapter 3 - Denudation

Question 1

What is denudation?

Answer 1

Denudation is the breakdown and removal of solid and loose rocky materials.

Question 2

What is weathering?

Answer 2

Weathering is the breakdown of rocks exposed on the earths surface. Unlike erosion, there is no transportation of the material involved

Question 3

Name the 3 types of weathering

Answer 3

• Mechanical
• Chemical
• Biological

Question 4

Explain mechanical weathering

Answer 4

Mechanical weathering occurs when rocks are broken into smaller pieces due to the action of sun and frost occurring in areas where there is no vegetation cover to protect the rock

Question 5

Explain chemical weathering

Answer 5

Breaking down of rocks due to chemical changes within the rock

Question 6

Explain biological weathering

Answer 6

Biological weathering occurs when tree roots or animals widen spaces within the rock or soil

Question 7

What is erosion?

Answer 7

Erosion is the breakdown of rocks AND the transportation of this material

Question 8

What causes erosion? Give examples

Answer 8

• Moving water, e.g. rivers and seas
• Moving ice, e.g. glaciers
• Moving air, e.g. wind

Question 9

What is freeze-thaw action?

Answer 9

Form of mechanical weathering.

1. Water gets into cracks in the rock
2. Water freezes putting pressure on surrounding rock
3. After some time, this continual temperature change puts pressure on the rock eventually causing it to crumble and break

Question 10

Explain exfoliation

Answer 10

• Form of mechanical weathering
• Occurs in areas of extreme temperature change
• When the temperature rises very high and falls very low, the rock expands and contracts causing the outer layer to shatter
• Also known as ‘onion peeling’

Question 11

What is carbonation?

Answer 11

1. Rain falls and takes in carbon dioxide forming a weak carbonic acid.
2. This rain then falls on limestone and reacts with the calcium carbonate in the limestone slowly dissolving it

Question 12

Define ‘karst’

Answer 12

Term used to describe distinctive landforms that develop on rock types (usually limestone) which are easily dissolved by water

Question 13

What is a limestone pavement?

Answer 13

An exposed area of limestone

Question 14

What are ‘clints’ and ‘grikes’?

Answer 14

• Clints are the flat areas of rock on a limestone pavement

- Grikes are deep fissures or cracks in a limestone pavement

Question 15

What is a swallow hole?

Answer 15

An enlarged grike is known as a swallow hole. Rivers and surface water dissapear through these swallow holes
E.g. Pollnagcolm in the Burren

Question 16

How are caves made?

Answer 16

When rivers dissapear underground though a swallow hole, Limestone is dissolved and passages eventually form large caverns or caves
E.g. Aillwee Caves in the Burren

Question 17

What are stalactites?

Answer 17

Drops of water containing calcium carbonate drip down from the roof of the cave, which in time drip to the floor. This leaves a tiny particle of calcite attached to the roof and over thousands of years these grow downwards forming columns of calcite

Question 18

What are stalagmites?

Answer 18

Drops of calcite fall from the stalactites onto the floor and these drops then evaporate leaving a build-up of calcite.

Question 19

What are pillars?

Answer 19

Pillars occur when a stalactite and a stalagmite grow together to form a pillar of calcite

Question 20

What is mass movement and what is regolith?

Answer 20

Loose weathered material that moves down a slope under the influence of gravity. This material is known as regolith

Question 21

Name 4 factors that affect mass movement

Answer 21

• Gradient
• Water content
• Human activity
• Plants and trees

Question 22

Describe a soil creep

Answer 22

• Slowest type of mass movement (around 1cm per year)

- Greatest at surface, decreases with depth of soil

Question 23

What evidence of soil creep do we see on the landscape

Answer 23

• Tilted telegraph poles
• Broken and tilted fences
• Soil piled up behind walls causing them to bulge and collapse
• Terracettes
• Tree trunks turned downslope
• Cracks in the road

Question 24

Describe bog bursts

Answer 24

Occur in upland slopes when bogs become saturated causing the bog to flow down the hillslope causing devastation as it travels

Question 25

Describe mudflows

Answer 25

Occurs when saturated regolith flows rapidly downslope

Question 26

Describe landslides

Answer 26

Occur when a slope becomes unstable, resulting in a very rapid movement of regolith down a steep slope

Question 27

Describe an avalanche

Answer 27

Occurs when the weight of snow is too much for the slope to hold