• Rocks are broken down in situ • In situ means at the original place • Causes of weatheringExtreme Freeze- Action of Action oftemperature thaw water plantschange action
In the day, very high temperature heats upthe surface of the rock and causes it toexpand.At night, very low temperature cools thesurface of the rock and causes it to contract.Alternate expansion and contraction of therock surface weakens the rock.Over time, the rock surface will peel off.
When temperature falls below freezing point,water in the cracks of rock turns into ice.The ice will expand, widening the cracks.When temperature rises above freezingpoint, the ice in the crack will melt.Repeated freezing and melting will cause thecracks to become wider and the rocks willbreak apart.
Water freezingin the joint
Joint iswidened anddeepened
Rock breaks down
• Rain will combine with carbon dioxide inthe air to form acid rain.• The acid rain will seep into the cracks ofrocks and dissolve part of the rocks.• Over time, the acid rain can corrodelandforms and buildings.
• Seeds can be carried by wind into cracks ofrocks.• Roots can grow into the cracks of rocksand widen the cracks.• Over time, the rocks may break apart.
• Rocks are broken down and areremoved from their original site• Causes of erosionWaves Wind River Flow
• Waves will hit the rocks on the beachconstantly.• The rocks will be broken down either by theforce of the water or by the materials carriedby the waves.• The broken rocks will be removed.• Over time, features such as cliff, cave andarch may be formed.
• Wind picks up sand in the deserts and hitsagainst the rock surface.• As sand is heavy, it can only be carried bywind to a certain height.• Wind erosion can therefore take place nearthe base of rocks.
• Rivers have energy to carry small materialslike sand and silt, as well as large materialslike pebbles.• These materials will erode river beds andriver banks along the path of the river.• Over time, the river will deepen and lowerthe Earth’s surface.
Broken rocks together withdecomposed leaf litter will form fertilesoil which is good for farming. (+)Beautiful landscapes such as rivervalleys, will be formed and attractingtourists. The country’s economy willprosper from the earnings from tourism.(+)
However, erosion can bring negativeimpact too. Landslides may occur andthere will be a loss of lives and houseswill be destroyed. (-)Statues will be corroded and destroyed.Government has to spend large sum ofmoney to maintain the statuesregularly. (-)
Physical landscapes will bedestroyed and fewer tourists willvisit the areas. The country’seconomy will be affected as lessincome is earned from tourism. (-)