Erosion and Weathering

Question 1

freeze-thaw

Answer 1

Water - eg from rainfall or melting snow and ice - becomes trapped in a crack or joint in the rock.
If the air temperature drops below freezing, the water will freeze and expand by 9-10 per cent putting pressure on the rock.
The ice will melt when the temperature rises above freezing.
If this process happens repeatedly, the rock will weaken and eventually shatter into angular fragments.
The fragments may then be deposited as scree at the foot of a slope.
It is most effective where the temperature fluctuates around 0°C, eg on north-facing high altitude slopes in Snowdonia.

Question 2

Biological weathering

Answer 2

Biological weathering is the weakening and subsequent disintegration of rock by plants, animals and microbes. Growing plant roots can exert stress or pressure on rock. Although the process is physical, the pressure is exerted by a biological process (i.e., growing roots)

Question 3

Chemical weathering

Answer 3

Carbonation is another type of chemical weathering. Carbonation is the mixing of water with carbon dioxide to make carbonic acid. This type of weathering is important in the formation of caves. Dissolved carbon dioxide in rainwater or in moist air forms carbonic acid, and this acid reacts with minerals in rocks.

Question 4

Abrasion?

Answer 4

When a wave breaks, the trapped air is compressed which weakens the cliff and causes erosion. Abrasion. Bits of rock and sand in waves grind down cliff surfaces like sandpaper. Attrition. Waves smash rocks and pebbles on the shore into each other, and they break and become smoother

Question 5

Hydraulic?

Answer 5

Hydraulic action is the erosion that occurs when the motion of water against a rock surface produces mechanical weathering. Most generally, it is the ability of moving water (flowing or waves) to dislodge and transport rock particles

Question 6

Attrition

Answer 6

Attrition is a form of coastal or river erosion, when the bed load is eroded by itself and the bed. As rocks are transported downstream along a riverbed, the regular impacts between the grains themselves and between the grains and the bed cause them to be broken up into smaller fragments

Question 7

Solution

Answer 7

Acids contained in sea water will dissolve some types of rock such as chalk or limestone.